Food Report Final Document

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UK SenSing

technologieS for

contamination

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OvERviEw 7

iNTROduCTiON 8

FOOd aNd dRiNK CONTamiNaTiON 8

CONTamiNaTEd PROduCTS 11

TyPES OF PhySiCal CONTamiNaTiON 12

haCCP 15

RECENT high PROFilE iNCidENTS 15

REPORT ObjECTivES 16

PRimaRy ObjECTivE 16

SECONdaRy ObjECTivE 16

ChallENgES 17

mEThOdOlOgy 18

CuRRENT dETECTiON aPPROaChES 19

CuRRENT aPPROaChES 20 ElECTROmagNETiC SPECTRum 20 ON-liNE TEChNiquES 21 X-Ray imagiNg 21 X-Ray SPECTROSCOPy 23 RamaN SPECTROSCOPy 25 viSual iNSPECTiON 27 iNFRaREd TEChNiquES 28 hyPERSPECTRal imagiNg 31 OPTiCal SORTiNg 33 TERahERTz imagiNg 35 miCROwavE dETECTiON 37 ulTRaSOuNd 39 magNETiC SEPaRaTiON 41 mETal dETECTiON 42 SamPliNg 43 ElECTRiCal imPEdaNCE 44

OFF-liNE / lab-baSEd TEChNiquES 46

biOSENSORS 46

NuClEaR magNETiC RESONaNCE 47

miCROSCOPy 49

maSS SPECTROmETRy 51

ChROmaTOgRaPhy 52

POlymERaSE ChaiN REaCTiON 53

ENzymE-liNKEd immuNiSORbENT aSSay 54

aTP biOlumiNESCENCE 55

TEChNOlOgy SummaRy TablE 56

ChallENgES 57

1. ThE dETECTiON OF glaSS FRagmENTS

– iN PaRTiCulaTE FOOd 58

baCKgROuNd 58

taBle of

RELEV

ANCE

ACTIVITY

OTHER PLASTIC PESTS

8%

9%

21%

3% 3%

7 TH

PHYSIC

AL

TO THE FSA

INCIDENTS REPOR TED LARGEST C AUSE OF

IS THE

CONTAMINA TION

FOREIGN

OBJECTS

IN FOOD

(2012)

ANIMAL

3%

METAL

32%

PLASTIC

8%

PESTS

21%

WOOD

3%

7 TH

PHYSI

CAL

TO T

HE F

SA

INCIDEN TS REPOR TED LARGEST CAUSE OF

IS THE

CONTAM INATION

FOOD INCIDENTS

REPORTED TO

THE FSA

2000

421 2012

1604

HIGH MEDIUM LO

W

Activity level within each sector

compared with relevance

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The Food Standards Agency (FSA) publishes data which shows a wor-rying – and increasing - amount of complaints due to contamination in food and drink. Complaints have risen year on year driven by numer-ous factors such as more mechanized process chain, higher consumer awareness, and more readily available and thorough testing equip-ment.

Physical contamination of food and drink from well-established food in-dustry materials such as metal , plastic and glass still manage to evade the carefully constructed safety mechanisms established to trap them - frustrating manufacturers. Reported Incidents of contamination cause recalls of a product, costing money and severely harm food companies reputation - devastating to an industry who rely on consumer confi-dence. This problem is complicated given the varied and ever-increas-ing variety of materials, which are able to find their way into the food production chain.

The industry needs to be aware of what innovative sensing technolo-gies are being developed not only in the food sector but in other sectors also.

There are however inhibiting factors to innovation in this sector; food industry representatives are often looking for better versions of what al-ready exists. Engagement events are key to exposing the up and com-ing technologies to food industry representatives to technology areas outside of their own areas of expertise and sector.

Although a huge industry, the food industry can be very conservative in the adoption of new technologies and it can require much higher rates of return on capital investment than can be delivered, therefore the food industry seeks low- cost solutions that can justify the effort. The idea that product recalls can be reduced or prevented by better training, procedures etc. is a far more appealing alternative to large R&D invest-ments.

There is however, a plethora of new technologies whose sensitivity, specificity, cost and overall performance are beginning to align with the needs of the food industry. Optical methods can provide real-time im-aging across many wavelengths to not only detect, buy characterise food properties as it passes through a factory. Techniques that can pen-etrate objects and visualise inside packages with abilities beyond what is achievable with X-rays only are being developed for Earth observation and military purposes which could find an unexpected application. Valuable insight to this report was provided by interaction with food companies through an online questionnaire, direct discussions and an

interactive workshop help on the 25th_{February 2014 in London which}

bought together food industry experts, membership organisations and technologists in technologies identified as potentially useful by the Knowledge Transfer Network prior to the workshop.

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FOOd aNd dRiNK CONTamiNaTiON

Foreign body contamination in food is one of the major sources of com-plaints against food manufacturers [1]. ‘Incidents’ are hugely damaging for manufacturers as they can lead to injury, loss of brand loyalty and large recall expenses.

Many public incidents such as glass contamination, E-coli, horsemeat in products labelled beef have shaken trust in the industry and made the public aware of how vulnerable parts of the food chain are to both intentional and non-intentional adulteration.

Figure 1 shows the number of ‘incidents’ in food from 2000 in the UK, the increase should cause alarm for all involved (Refs. 2,3,4).

The trend of increase was stalled slightly from 2006 – 2009, the subse-quent increase could be due to a few factors;

Since 2009 the number of pesticide residue ingredients has increased substantially. In 2011 and 2012, this was due partly to increased testing of okra at border inspection posts

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1604 1714 1505 1208 1298 1312 1344 966 789 743 530 476 421

Figure 1. Number of food incidents, 2006 - 2012 adapted from Ref. 3

1. Edwards, M. (2004) Detecting foreign bodies in food, Cambridge: Woodhead Publishing Limited. 2. http://food.gov.uk/multimedia/pdfs/incidentsar.pdf Food Standards Agency (2007)

3. http://food.gov.uk/multimedia/pdfs/incidents-report-2012.pdf Food Standards Agency (2013)

4. It is important to appreciate that these figures are and are expected to be largely underestimated, by as much as a factor of 200 suggested by some at the Workshop. This misrepresentation could be die to a variety of reasons:

The severity of some of the incidences will bias figures towards those, for example, people will be more likely to •

report a piece of glass than a fish bone.

Once a problem is identified, mass withdrawals can hide the extent of the actual problem •

Failure to report to the FSA •

Despite these obvious failings of the acquired data, the data is expected to be representative of industries problems.

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Incidents involving strains of salmonella has averaged out at 45 a year during 2006 – 2009. In 2010 they rose steeply to 118 and fell only to 98 in 2012. Our investigations suggest that this increase was mostly the result of paan leaves imported from Bangladesh (Ref. 3)

The food and drink incidents are broken down into incident type in Fig-ure 2 for years 2006 and 2012.

Figure 2. Incident by category 2006 and 2012, Ref.3

Physical contamination is one of the key subject areas of this report and in 2012 represented 7 % (the seventh largest category) of the total number of complaints. In Figure 3, specifically the incidents relating to physical contamination incidents

The “number of incidents falling into this category increased from 93 in 2011 to 107 in 2012. In particular, incidents relating to metal contamina-tion increased from 19 incidents in 2011 to 34 in 2012”, Ref. 3

Water quality Veterinary medicines Use of an unauthorised ingredient TSE Radiological Process contamination Physical contamination Pesticides On-farm Natural chemical contamination Microbiological contamination Labelling / documentation Irradiated ingredient Illegal import / export Food contact materials Environmental contamination Counterfeit product Biocides Animal feed (on market) Allergens

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Overall the physical contamination incidents have not been improved by a statistically significant amount over the past 6 years but for a slight dip in 2009.

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139 123 110 56 116 93 107

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CONTamiNaTEd PROduCTS

In Figure 4, the breakdown of all incidents in 2012 is shown by the food type they occur in. The highest categories of contamination are fruit and vegetables, meat and meat products and nuts and seeds. The range of detection schemes needed by the food industry is compounded by this large number of food mediums available.

Figure 4. Incidents by food type 2012

Incidents not related to a specific food Other foods Wine Water Eggs and egg products Fats and oils Cocao preparations, coffee and tea Alcoholic beverages (other than wine) Crustaceans Poultry and poultry meat products Non-alcoholic beverages Animal feeds Soups, broths and sauces Herbs and spices Milk and milk products Fish and fish products Dietic foods and food supplements Confectionary, honey and royal jelly Molluscs Cereals and bakery products Prepared foods and snacks Nut, nut products and seeds Meat and meat products Fruit and vegetables

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TyPES OF PhySiCal CONTamiNaTiON

The types of physical contamination present in food vary largely de-pending on the type of food in question, below is a short list of various contaminant types of concern:

Wood • Plastic • Metal • Glass • Animal origin •

Paper and cardboard •

and many more •

Figure 5 and Figure 6 show the types of foreign object complaints in 2006 to 2012 (from Refs. 2 and 3). Whilst the total number of foreign ob-jects incidents each year has fallen from 139 to 107 in this time period, the proportion of metal incidents has risen and high-risk incidents such as plastics and glass remain high. The reason for this may be due to a more automated and mechanised supply chain.

Figure 5. Breakdown of the complaints made about foreign objects by object type (2006)

Figure 6. Breakdown of the complaints made about foreign objects by object type (2012) Metal Pests Plastic Glass Animal Origin Wood Rubber Other 8% 13% 12% 19% 19% 2% 3% 24% Metal Pests Plastic Glass Animal Origin Wood Rubber Other 8% 13% 12% 19% 19% 2% 3% 24% Metal Pests Plastic Glass Animal Origin Wood Stone Rubber Other 8% 9% 21% 32% 19% 3% 1% 3% 3% Metal Pests Plastic Glass Animal Origin Wood Stone Rubber Other 8% 9% 21% 32% 19% 3% 1% 3% 3%

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chain can occur as producers are under pressure to minimize pesticide applications. The use of biological pest control may mean that damaging insects are absent and the crop is in good visual condition, however the predator insects may be on the produce and brought into the food supply chain.

glass as the fourth largest concern can enter at this stage and through out as contaminants in the ground or later contamination by broken lights etc. although the later contamination risk is mitigated by the prevalence of factory safe light fittings.

The fat and gristle content of meat varies hugely from animal to animal and is determined at this stage in the chain.

incorrect labeling can occur at any point throughout the entire food chain, making traceability and due diligence a key aspect of food manufacture.

haRvESTiNg The harvesting process can pick up bad produce as well as physical contaminants that are present in the environment; screening is usually base heavily on visual inspection at this point.

whilst plastics can enter throughout the chain, major sources are often at the industrial processing stages, conveyer parts and tools for example. again, for metal, mechanised processes often increase the likelihood of contamination at the processing stages, nuts, bolts etc.

The fat and gristle content of meat are controlled at this butchery production stage.

Fruit and vegetables are harvested at their ripest and checked for damage often by visual inspection after having been harvested indiscriminately. depending on their level of ripeness mold contamination can occur at any stage subsequently.

TRaNSPORTaTiON Raw maTERial PROCESSiNg (milliNg, abaTTOiR)

Bone can remain in meat and poultry products after incomplete filleting and de-boning.

Extraneous vegetable matter (Evm) can remain during the milling process due to its similar composition to the parent foodstuff.

COllaTiON / TRaNSPORTaTiON

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Operators – objects that are introduced by the operators of the machinery, hair, plasters, jewelry etc

FOOd PROCESSiNg & aSSEmbly COllaTiON, TERTiaRy PaCKagiNg, STORagE diSTRibuTiON RETailER RdC OR whOlESalER / CaTERER / STORagE

RETail diSPlay Contaminants beyond this stage are now out of the manufacturers ability to monitor.

CONSumER PuRChaSE &

TRaNSPORTaTiON The consumer assesses ripeness in fresh fruit and vegetables at this stage.

hOmE STORagE FOOd PREPaRaTiON PRESENTaTiON aNd CONSumPTiON

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haCCP

Obviously, for foreign object contamination, prevention is better than cure and systems such as the Hazard Analysis and Critical Control Point (HACCP) exist which set out procedures for maintaining safe to eat food.

Hazard Analysis and Critical Control Point (HACCP) is a system that helps food business operators look at how they handle food and intro-duces procedures to make sure the food produced is safe to eat. Ref.

5._{As part of routine inspections, the enforcement officer will check that}

the business has an appropriate HACCP-based food safety manage-ment system in place.

However, when these preventative steps fail, procedures and tests must be in place to detect these objects, ideally identify them and ideally lo-cate the source of the contamination.

Workshop delegates have additionally provided thought on the useful-ness of sensors to not only directly detect contamination events, but also in the behavior i.e. the breaches of HACCP which can inevitably lead to incidences.

RECENT high PROFilE iNCidENTS

Table 2. Recent high profile incidents 6,7,8,9,10,11,12,13,14

iNCidENT

REF

Cigarette in mushrooms wasp in Chocolate Toenail in Pasta Sauce Cocaine in Soft drink horsemeat scandal Caterpillar in Sweetcorn Peanut in Stuffing metal in Pudding allegens in hot dogs

2014 2014 2012 2013 2013 2014 2014 2014 2014 [6] [7] [8] [9] [10] [11] [12] [13] [14] 5. http://www.food.gov.uk/business-industry/caterers/haccp/ 6. http://www.dailymail.co.uk/news/article-2549331/Father-buys-pack-mushrooms-Co-op-store-finds-cigarette-hidden-inside-given-just-92p-refund.html 7. http://uk.news.yahoo.com/wasp-found-inside-cadbury-dairy-milk-jake-keating-142659377.html#nHMfprI 8. http://uk.news.yahoo.com/aldi-customer-tracy-arnold-from-wisbech-shocked-after-finding-nail-in-pasta-sauce. html#mFVJ3Ri 9. http://www.food.gov.uk/news-updates/news/2013/dec/caribbean-soft-drink#.UvUan17t0_V 10. http://www.telegraph.co.uk/foodanddrink/foodanddrinknews/9859946/Horse-meat-scandal-More-contaminated-food-likely-to-be-found.html 11. http://www.dailymail.co.uk/news/article-2553800/Mother-finds-INCH-long-caterpillar-inside-tin-sweetcorn-bought-Aldi.html 12. http://www.food.gov.uk/news-updates/allergy-news/2014/feb/sainsburys-stuffing#.U1pwXl6ppuY 13. http://www.food.gov.uk/news-updates/recalls-news/2014/feb/metal#.U1pwql6ppuY 14. http://www.bbc.co.uk/news/business-27100284

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This document aims to cover current detection systems used for a num-ber of food and drink related complaints with input from food manu-facturers current technologies will be assessed for their strengths and weaknesses. Through communication with manufacturers, technologist and consultancies future technologies are also highlighted.

The UKTI have identified key challenge areas to be met in the field of contaminant sensing in food production. During the consultation period further challenges (in purple) have been identified and added in addi-tion to the initial 10. This report has been compiled by the Knowledge

Transfer Network through communication with food manufacturers,

sensor technologists and consultants and aims to detail the UK capa-bilities in contaminant sensing in food.

PRimaRy ObjECTivE

The eventual aim will be to provide to the UKTI a report that can show-case the UK strengths in food sensing in its current state and also the capacity for the UK technology base to innovate the market and respond to the requirements of the food industry.

SECONdaRy ObjECTivE

Creation of publishable capabilities database highlighting UK compa-nies working in food sensing technologies as well as UK academic re-search groups working in relevant disciplines

report

oBjectiveS

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1. The detection of glass fragments in liquid products filled into glass bottles

The detection of glass fragments in particulate food products such 2.

as nuts or breakfast cereals

The detection of plastic in any sort of food product, wet or dry, 3.

particulate or homogenous

The detection and sensing of fat, gristle, cartilage etc. in meat, 4.

prepared meat and poultry products

The detection of bone in meat and poultry products and bone in fish 5.

The detection insects in fruits and vegetables 6.

The quantification of ripeness in fruits 7.

The detection of damage and of mould in fruits and vegetables 8.

The identification of the wrong product in a package (e.g. fish pie in 9.

a meat pie packet)

The detection of “natural plant materials which should not be 10.

there”, for example stalks in dried fruits, shell fragments in nut products, dense or wet lumps in breakfast cereals

The detection of hair and fibre in any sort of food product 11.

The detection of metal in any sort of food product 12.

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Resources for this report have been gathered through a combination of desk research, Internet searching, communication with food indus-try manufacturers (through the Biosciences community), developers of food sensing technologies and relevant consultants. A full list of organi-sations assisting in the study are gratefully acknowledged and can be found in Annex 1: Inputs to this study

The first stage of the project has been to identify the key challenges in food sensing, 10 were initially suggested by the UKTI - further chal-lenges were identified during the consultation procedure.

The next stage has involved communication with food manufacturers to see how currently these challenges are being met. Potentially use-ful technologies were highlighted in these discussions and companies working in these areas were contacted for their input.

The final stage of consultation was through the running of an interactive workshop where food industry experts, technologists and membership organisations were invited to attend to discuss a draft report prepared by the Knowledge Transfer Network

This data from the food manufacturers is shown on pages 17 – 46. The methods used are displayed graphically - key comments made were also extracted.

Provide a comprehensive study of the challenges faced by food •

manufacturers

Identify key technology areas to meet the challenges •

Promote opportunities for sensor companies in the food sector •

Provide a map of UK capability in the contaminant sensing sector •

Provide a networking opportunity for interested parties •

The final report will be made available on the Knowledge Transfer Net-work website – freely downloadable for all interested parties, who could include:

Sensor companies with an interest in non-destructive evaluation in •

food processing

Food processing companies who wish to investigate options for •

detection

People working in linked sectors with an interest in foreign body •

detection

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There are a few important qualifiers that a detection scheme should be compared against ultimately determining whether it is appropriate for its purpose. The respondents to the questionnaire were asked to consider the following qualifiers.

The cost of a device is always a concern for manufacturers. High instal-lation costs can sometimes be countered by low maintenance costs. However, it should be noted that the price of safety infractions can be very high not only in fines, but in recalls and loss of consumer cred-ibility.

The ease of use covers how complicated the device is to operate and how easy the results are to interpret. This is linked strongly with cost – if a team of technicians are required to operate, monitor and maintain the device then it may become economically non-viable.

The sensitivity of the device will determine how small a foreign con-taminant can be discovered and how accurately a characteristic can be measured. This is clearly an important feature as small shards of glass for example can be just as dangerous and large chunks.

The speed of a measurement will determine the throughput of food to be checked. Slow time-consuming measurements may end up reveal-ing more accurate results but the time lost may not be worth it, and vice versa a very quick machine that has very high throughput but misses every other object will not be wanted. Speed also encompasses how quickly results take to be analysed; can they be done on sight? Do they need a lab?

The specificity of the device will determine whether it is capable of identifying specific information about a contaminant. For example, can it tell the user exactly what type of plastic is in my food? Information such as this is invaluable when locating the source of a contamination – as this can save manufacturers vast amounts of money in lawsuits, shorter shut down periods etc.

What is the size of the detector? The platform for the sensor device can vary from a large factory based scanner, a hand held device, mo-bile phone integrated sensor, on product sensor (a sticker for example). There are obviously advantages for more discreet sensors in food pro-duction locations where space is at a premium.

Additional extras: are there unique properties to the device that aren’t

covered above, can it measure more than one contaminant? Penetra-tion depth? Can it be retrofitted to existing lines? – a large barrier to entry in this market, etc.

The following pages provide some detail on the technologies currently being used, along with their advantages and disadvantages. They are divided into off-line techniques, on-line techniques and potential

techniques for innovation that aren’t yet in wide scale use.

cUrrent

detection

approacheS

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The approaches identified are separated into on-line and off-line tech-niques, they are assessed based on their technological capabilities, their applicability to food contaminant sensing both for liquids in a pipe and particulate food on a conveyor, pros and cons and (if applicable) the UK capabilities

For off-line techniques, comment is not made on their applicability to pipe and conveyor - they are included for completeness.

As many of the techniques listed below are based on either the absorp-tion of scattering of parts of the electromagnetic spectrum, it is perhaps useful to remind the reader where the different regimes lie.

Figure 7. The electromagnetic spectrum, taken from Ref. [15]

15. http://www.physik.uni-kl.de/en/beigang/forschungsprojekte/

cUrrent

approacheS

electromagnetic

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X-Ray imagiNg

X-ray imaging uses the absorption / transmission of X-rays to

produce images. These images relate to the cross-sectional density of the material being probed. Both two and three - dimensional images can be constructed using tomographic imaging. Whilst some manufacturers may express concern over the quality of food after being subjected to X-rays – the World Health Organisation (WHO) have confirmed that food radiation levels up to 10,000 Sv do not affect food safety or nutritional value - doses used in inspection technologies are significantly lower than that.

Due to the ability for X-rays to differentiate materials of differing densi-ties, X-ray imaging can be used to identify contaminants such as metal, stone, glass, dense plastics and calcified bone. These machines are commonplace in food inspection lines due to their low maintenance needs and the relatively easy interpretation of results. The future for X-ray imaging could include the incorporation of material discrimination and fat analysis into one system.

The sensitivity and range of application of the X-ray inspection meth-ods could be increased by the addition of energy sensitivity, allowing unique identification between thickness and material changes, and thus increasing the contrast of low absorption materials such as plastics and organics.

The benefits of using energy X-ray sensitive detectors to detect impuri-ties is well understood, but it has probably not been adopted for in-line food inspection as the existing technology using CdTe or Ge is prohibi-tively slow and too expensive.

aPPliCabiliTy TO liquid iN PiPES

Due to the low absorption cross-section of materials available for in-dustrial food processing pipework – the application of X-ray imaging systems through pipes is not unusual. There exist on the market pipe-line X-ray systems for the continuous inspection of pumped products – suitable for fluids, semi-solid products such as sauces and fruit prepa-rations.

aPPliCabiliTy TO PaRTiCulaTE FOOd ON a CONvEyOR

X-ray systems are well suited for quickly identifying abnormalities in line product products. The image processing and rejection decisions can be made automatically with pattern recognition software of by human monitoring in a way similar to airport package monitoring.

on-line

techniqUeS

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Table 3. X-ray imaging usefulness in the food sector [16]

PROS aNd uSES

CONS aNd limiTaTiONS

Can penetrate deep within the sample travelling through packag-ing. it is a non-destructive technique, non-contact technique Capabilities: metal • glass • Stones • Calcified bones • PvC plastic • Teflon • Ceramics or concrete •

Flavour / sugar clumps •

missing product •

applicable for ready meals, pre-pared foods, meat, bakery products, cereals, dairy foods, confectionary, vegetables, fruit, cosmetics.

The X-ray beams are ionis-ing – this causes little to no damage to the food under in-spection but can cause health problems for operators acci-dently exposed to the beam. limitations: low-density plastics • Thin glass • low-density stones • insects • wood • hair • Cardboard • Paper • Non-calcified bones • liNKEd SECTORS

Healthcare: Perhaps the most common use of X-ray imaging is in

med-ical healthcare where 2D and 3D images are constructed of patient inte-riors. Hard X-rays are also used in the medical treatment of cancer.

Material Science: Hard X-rays are often used in material science for

non-destructive testing of crystallographic information etc.

Astronomy: There are various sources of X-rays in the Universe which

are studied by scientists, detectors for hard radiation are used in this sector.

Security: A very common use of X-ray imaging is in security

applica-tions to see through packaging and luggage for non-destructive secu-rity testing.

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X-Ray SPECTROSCOPy

X-ray spectroscopy uses the scattering or absorption of X-rays to

pro-vide qualitative information on the electronic structure of the sample. Absorption and scattering of X-rays gives a material dependent spec-trum allowing for identification and composition of various materials. X-ray spectroscopy can be found in off-line and on-line solutions to food quality testing. Unlike X-ray imaging however the technique of-ten requires more complicated detection systems than X-ray imaging by use of X-ray dispersive optics or solid-state X-ray energy analyzers. Some examples from Ref. 23 of X-ray spectroscopy are EDAX analysis to determine phosphorous content of potato starch and also as trace element detection for specific contaminant detection. A further example

of ham identification is detailed in Ref. [17_{] – high flux synchrotron}

ra-diation identified signatures in cured ham unique to the curing process helping to establish a test against ham fraud.

For spectroscopy techniques in the photo absorption regime, X-rays are often tuned to core energy levels of electronic structures – this often puts the energy of the X-rays at the low energy end that severely limits the penetration depth. Spectroscopy through pipes and semi solid

liq-uids would be difficult to achieve [18_].

An easier application for X-ray spectroscopy measurements would be in particulate solids on a conveyer, X-rays would only penetrate mini-mally into the surface and collection and analytical time may however severely limit throughput.

17. http://www.esrf.eu/Apache_files/Newsletter/ESRFNewsSep2010.pdf

18. There are spectroscopic techniques higher in energy, although the application of these would be fraught with difficulty for interpretation.

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Table 4. X-ray spectroscopy usefulness in the food sector

PROS aNd uSES

CONS aNd limiTaTiONS

Very specific method of identification

Can penetrate deep within the sample, travelling through packaging

Scans can take longer than X-ray imaging Capabilities: metal • glass • Stones •

Bones (only calcified) • PvC plastic • Teflon • Ceramics or concrete •

Flavour / sugar clumps •

missing product

applicable to ready meals, prepared foods, meat, bakery products, cereals, dairy foods, confectionary, vegetables, fruit, cosmetics.

Spectrum analysing sources require complicated

equipment.

Energy dispersing CCds or solid state detectors are expensive

Only reasonable small areas can be examined at a time limitations: low-density plastics • Thin glass • low-density stones • insects • wood • hair • Cardboard • Paper • liNKEd SECTORS

Material Science: soft X-rays are often used in material science for

non-destructive testing, electronic structure analysis, magnetic infor-mation, compositional analysis etc.

Astronomy: There are various sources of X-rays in the Universe that

are studied by scientists, detectors for hard radiation are used in this sector.

Healthcare: In pharmaceuticals X-ray spectroscopy is routinely used

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RamaN SPECTROSCOPy

Raman Spectroscopy is a method of vibrational spectroscopy long known to the condensed matter physics world and is a technique which provides information on rotational and vibrational modes in materials – as such provides ‘fingerprint’ information of substances that are unique to that substance.

In Raman spectroscopy, a sample is illuminated by a monochromat-ic light source, this light is used to promote electrons from vibrational states into higher level virtual states, as the electron falls back into its ground state, light is radiated which is specific to that vibrational state (Figure 8). The scattered light is then measured on a detector. Summing over all the present vibrational states results in a spectrum that is unique to a substance.

In food technologies, Raman spectroscopy may be used as a tool for quality control, for compositional identification (fatty acid composition, fish and meat muscle quality) or for the detection of adulteration, as well as for basic research in the elucidation of structural or conformational changes that occur during processing of foods (changes in proteins, water and lipids that occur during deterioration), Refs [19 and 20].

Obtaining Raman spectra from liquids or semi-solid liquids is possible wherever there are molecular bonds – fast moving, inhomogeneous samples however will prove difficult to obtain a good Raman spectrum for.

The speed of data collection can again cause difficulties for on-line de-tection, but it is classed here as an online technique due to its abilities as a remote detection scheme. Another issue may be the small sample volumes obtainable – as to the best of the authors knowledge, wide-field Raman imaging is not a well established technique [21].

19. Raman Spectroscopy a promising technique for quality assessment of meat and fish: A review, Food Chemistry, 107, 1642 (2008)

20. The applications of Raman spectroscopy in food science, Trends in Food Science & Technology, 11, 361 (1996) 21. There are methods, however, available for building Raman images, but these often rely on point by point scanning and can be very time consuming, Raman Imaging: Techniques and Applications. Arnaud Zoubir, Springer Series (2012)

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Table 5. Raman usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

Non-contact Non-destructive

Can be enhanced greatly using nanostructures to provide surface-enhanced Raman scattering which can be capable of single molecule detection levels very weak response to water

No commercial solutions for food

Fluorescence can be a problem for detection. Hard to develop wide field solutions

liNKEd SECTORS

Healthcare: Raman gas analysers are used in medicine for real-time

monitoring of anesthetic and respiratory gas mixtures during surgery.

Pharmaceuticals: identification of pharmaceutical constituents can be

made using Raman.

Security: Raman scanners have found a large market in airport security

due to their fingerprinting abilities [22].

Figure 8. Example of Raman spectroscopy of native starches from Ref. [23]

22. http://physicsworld.com/cws/article/news/2012/feb/07/raman-technique-peers-into-cabin-baggage 23. Characterization of Irradiated Starches by Using FT-Raman and FTIT Spectroscopy, Journal of Agricultural and Food Chemistry, 50, 3912 (2002)

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viSual iNSPECTiON

Visual monitoring of foodstuffs uses humans as resources to watch the food move past, any thing that doesn’t conform to the standard is taken from the production line. The definition of non-conformity is vital to be established from the outset. Many production facilities set out the crite-ria for non-conformity see Refs [24] for examples.

Only very obvious problems can be identified using visual inspection of food and liquids in pipes, more often that not - visual inspection is enhanced by providing the use of X-ray technology for the inspector to see through obstructing pipes.

Visual identification is easier for discrete items on a conveyer than in a pipe, again is assisted by the use of non-standard imaging techniques to assess uniformity. Other sensory inspection could help here, such as smell or touch.

Table 6, Visual inspection usefulness to the food sector

PROS aNd uSES

CONS aNd limiTaTiONS

Non-destructive technique Can be used as a monitor for many defects in one

very resource intensive highly variable outputs

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iNFRaREd TEChNiquES

Near Infrared (NIR) spectroscopy uses the different absorption

condi-tions of different compounds to analyse the constituent elements of a sample. The NIR region extends – roughly – from 800 nm to 2500 nm and is thus very well suited for the detection of organic compounds. The technique uses transition probabilities of photons to map the states in a material.

In the food industry NIR spectroscopy has been used for many years to determine the food quality in an accurate, non-destructive and rapid way. Due to its sensitivity to organic content (water, sugar, acids etc.) - It can be used to determine moisture, fat and protein content and other components that impact on product quality and safety. some firms are currently marketing NIR based sorting and grading systems for use with citrus, pome and stone fruits As well as being able to detect the pres-ence of organic content the technique can be used to fingerprint what the content is (useful for pathogens, allergens etc) and with plastics be-ing composed of organic chains, plastic contaminants can not only be located, but also identified.

MIR is very rich in the information it provides for organic materials in terms of the fine structure in the spectrum.

There are product solutions of pipe-mounted NIR liquid process cells for monitoring. NIR spectroscopy, however, suffers from strong absorp-tion in water, as such applicability to liquids in pipes may be limited and the penetration depth of the NIR beam would severely limit the diameter of the process pipe.

Particulate food on a conveyer is well suited for NIR inspection and there are products that analyse the NIR spectrum of food and bever-ages. Quicker measurements are available by sing FT-IR spectroscopy (see one of the following next sub-section).

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Table 7. NIR usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

Easier maintenance than X-ray machine

uses non-ionising radiation, i.e. safer than X-rays

Non destructive

Real-time measurements little or no sample preparation due to its sensitivity to moisture, proteins, fats and sugars it is ideally suited for the dairy industry

good applicability to fruit good applicability to identifying presence of organic content

Short penetrating length ingaas or PbS detectors less sensitive then visible CCds. The strong absorption in water has historically limited the use for assessment of fresh produce

Calibration limitations

liNKEd SECTORS

Astronomy: spectral information can tell astronomers about star types

and stellar formation and processes.

Healthcare: used to measure oxygen content of blood, and also can be

used on the skull to provide information of blood flow related to neural activity as a partial replacement for fMRI (functional MRI)

Materials: can be used to measure film thicknesses for optical

coat-ings.

The technique is closely linked with hyperspectral imaging (HSI) de-scribed in the following section, due to its proximity in the EM spec-trum, HSI is where optical measurements are combined with imaging to provide images containing not only spatial information but wavelength information. The difference in these technologies is often in the detec-tions scheme-in NIR spectroscopic information is often obtained using dispersive elements whereas in HSI, the detector is constructed as to observe many wavelengths simultaneously.

FT – iR SPECTROSCOPy

FT-IR (Fourier transform infrared spectroscopy) is considered a more sensitive and robust technique over dispersive NIR techniques de-scribed above by its lack of diffraction grating to separate out frequen-cies – instead interferograms are collected by a interferometer-like setup which represent the Fourier transform of the absorption spectrum.

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FT-IR has the following advantages over dispersive and filter methods of IR or NIR methods:

Table 8. Advantages of FT-IR over dispersive IR, from Ref [25]

PROS aNd uSES

it is non-destructive

Solids, liquids and gases can be analyzed

it is possible to easily identify and distinguish between many organic compounds and inorganic compounds

Precise measurement method that requires no external calibration FTiR measurements can be made within seconds

Optimal sensitivity – detectors are more sensitive and the optical throughput is higher. FTiR can identify small concentrations of contaminants.

mechanical simplicity – The mirror in the interferometer is the only moving part in the FTiR instrument, therefore making mechanical breakdown minimal.

Simultaneous analysis of multiple gaseous compounds

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hyPERSPECTRal imagiNg

The hyperspectral imaging (HSI) method combines digital imaging with spectroscopy for give detailed information across multiple ranges of the EM spectrum. Unlike single source detection systems, hyperspectral imagers collect data from across the electromagnetic spectrum. Hy-perspectral imaging can be perceived as an extension of multispectral imaging (MSI); while multispectral imagers look at light from up to 10 wavebands, hyperspectral imagers are capable of obtaining informa-tion in a more continuous fashion, over 100 wavebands. Data are there-fore not stored as two-dimensional images but instead as cubes, where the third dimension spans the wavelength range of the detector. These cubes are unique for every produce and serves as a reference for the sorting procedure.

The use in food can be in using the ‘fingerprinting’ ability to determine what the constituents of the passing food are and whether it should be there. Indeed there exist some commercial solutions already.

Many of the disadvantages of liquid in pipe sensing for NIR are shared with HSI.

HSI lends itself well to conveyor inspection lines - the advantage of simultaneous acquisition across many wavelengths allows quick gath-ering of vast amounts on information, see for example chicken carcass inspection Ref. [26].

PROS aNd uSES

CONS aNd limiTaTiONS

Non-contact, non-destructive due to the multi-wavelength approach vast amounts of data are recorded simultaneously large area detection

applications in differentiating organic components

Extraneous vegetable matter Stones and shells

meat and poultry contamination

Few commercial solutions Expensive detection systems for hSi

limited penetration length large storage capabilities required

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liNKEd SECTORS

Due to its fingerprinting and identification capabilities hyperspectral im-aging can find uses in various linked industries.

Astronomy: mapping the physical properties of cosmic hot gas. Security: in forensics hyperspectral imaging can be used for detection

of forged documents and fingerprints at crime scenes.

Environmental monitoring: Hyperspectral imaging can be used to

monitor vegetation and has been equipped to UAVs to detect large im-ages.

Medicine: extent of burns and bruises below the skin of the human

body, skin imaging for the diagnosis of skin cancers. In pharmacology it can be used discern the makeup of drugs that look identical to the naked eye and conventional imagers.

Figure 10. The image on the left shows raisins with impurities in between (paper, plastic). The blue and green arrows point two spectral positions of raisins. In the graph on the right it can be seen that points with similar color also have similar spectra behind. The red arrow points a different color. Taken from Ref. [27].

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OPTiCal SORTiNg

Optical sorting methods use advanced image recognition equipment

to automatically identify shapes, size, color and patterns of items that do not fit set parameters, current systems. The spectral information / images could be from any other optical sensor techniques shown above – more often than not however, they are based on monochromatic or tri-chromatic cameras.

Optical sorters are widespread in the food industry due to its in-line, non-destructive and low human resource use. Compared to manual sorting, which can be is subjective and inconsistent, the non-reliance on human resources helps improve quality of products, maximize through-put, increase yields and reduces labour costs. From Ref 28, in meat, it has been used to characterize muscle colour, marbling, maturity and muscle texture. In other applications sorting technologies have been used in agricultural products such as fruits, vegetables or grain.

In general, and optical sorting system is composed of four major com-ponents; the feed system, the optical system, image-processing sys-tem and the separation syssys-tem. The optical syssys-tem can be integrated with advanced technologies such as hyperspectral sources which as a great deal of functionality to the system.

The applicability and usefulness in pipes is essentially the same as that for inspection by humans, except it takes out the uncertainty and ran-dom errors associated with human monitoring.

See above

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Table 9. Optical sorting usefulness in the food industry [29]

PROS aNd uSES

CONS aNd limiTaTiONS

These systems can be very specific

automation means that human resource costs are low

100 %, on-line inspection applicable to: Seeds Coffee Fruit grain Nuts

due to the integration of robotics, can be reasonably expensive.

Can give information of the wrong shape and size, but not applicable to all types of defects

limited to transparent / surface incidents

liNKEd SECTORS

Pharmaceutical: in this sector optical sorting is used for optimizing the

end products of pharmaceutical products ensuring quality, efficient and reliability.

Industrial: can be used for automated machine building tasks, waste

recycling, tobacco processing.

A comparison of RGB imaging, NIR spectroscopy, multispectral imaging and HSI are shown below for a comparison (adapted from Ref. [30]).

Table 10. Comparison of RGB, NIR, MSI and HSI techniques

29. http://www.buhlergroup.com/global/en/process-technologies/optical-sorting.htm#.Uut1lHm4ml

30. Potential application of hyperspectral imaging for quality control in dairy foods, Gowen et al, Image Analysis for Agricultural Products and Processes, 65, (2011)

aTTRibuTE

Rgb

NiR

mSi

hSi

Spatial information

_P

Spectral information

_P

limited

_P

multi-constituent information limited

_P

limited

_P

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TERahERTz imagiNg

Terahertz (THz) radiation lies in-between microwave and the far infra-red on the EM spectrum generally with a wavelength range of between 100 µm and 1 mm corresponding to frequencies of 0.3 to 3 THz. Unlike microwave radiation it can penetrate a wide variety of non-conducting materials. Non-destructive evaluation, the energy of the THz band is 1 – 10 meV. T-rays are inherently sensitive to water; they are very suitable for moisture detection. Transparent to opaque materials such as plas-tic, fabric, ceramic and paper so the technology has the ability to see through some packaging materials.

THz has applications in food technology due to its strong interaction with water. Moisture content can be used to infer different properties of a foodstuff – fat content, ripeness etc. Its ability to see through plastics and card also make it perfect for NDE of packaged food

High water content materials are almost completely opaque to THz ra-diation, this in conjunction with possible metal piping means that THz imaging and spectroscopy has very limited uses to liquid phase food.

For less water intense materials, the opaqueness of water to THz can provide a wealth on information for moisture detection. Its ability to see through paper, plastic can check for missing items on a conveyor.

Table 11. THz usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

On-line, non-destructive technique

many more materials are transparent to Thz radiation (as compared with iR)

Non-ionising.

metal and polar liquids (such as water) completely opaque to Thz radiation

Thz radiation cannot penetrate metal Expensive sources and detectors are major obstacles for commercial devices

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liNKEd SECTORS

Due to the ability of THz radiation to penetrate common packaging and clothing materials there is interest from sectors such as:

Healthcare: unlike X-rays THz radiation is non-ionising and therefore a

safer alternative for medical applications. It also has the ability to distin-guish areas of different density and water content.

Security: the non-ionising properties of THz radiation also makes it an

attractive method for concealed weapon detection through clothing, the additional method of THz spectroscopy allow the unique fingerprints of substances to be exploited and identify concealed substances.

Manufacturing: uses in manufacturing, quality control and process

monitoring due to the transparent properties of cardboard and plastic, the inspection inside packaged goods can take place.

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miCROwavE dETECTiON

Microwaves are no stranger to the food industry – the ease at which microwaves are generated coupled with the strong absorption by water make them ideal for microwave heating devices. Detection systems that operate in the microwave part of the spectrum are far lower power - Ref. [1].

Microwave imaging is uncommon as the large wavelength for small objects result in diffraction effects and a severely limited image when compared with X-ray imaging for example. Microwave detection sys-tems instead rely on measuring the transmitted microwave field passing through a product and the local variation in dielectric properties between foreign objects and the product. Dielectric discontinuities are seen as absorption change of phase. Similar to THz radiation, though possess-ing higher penetration depths microwave radiation has a wavelength range of between around 1 cm and 30 cm corresponding to a frequency range of 200 MHz to 300 GHz.

Active microwave technology for this area is much closer to commer-cialization than THz equipment, with sources and detection methods well established from areas such as telecommunication. Unlike micro-wave ovens, the radiation used in low power and more similar to an X-ray imaging set-up. Additionally due to its response to water, microwave wavelengths have been proposed for use in measuring water content for ripeness determination, see Ref. [62].

A Swedish company – Food Radar – has commercialized a product us-ing microwave radiation; the transmission of the microwave radiation is dependent on the permittivity of the transmission medium. Foreign objects change a materials permittivity and the detected radiation can thus be monitored for contamination – applicable to liquids and emul-sions. It is claimed that glass (10 mg pieces), metal filings (5 mg), plas-tics, stones, wood and other organic materials can be detected with microwave techniques,

Microwave sensing can still be applied to food on a conveyor provided they are not in metal packaging – unpackaged, wood, plastic etc. But the technique is best suited for homogenous, piped foods if possible.

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Table 12. Microwave radiation usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

Non-contact, non-destructive very wide range of contaminant materials detectable by their microwave impedance.

No limits on speed of flow through the food-processing system. good for metal, glass, stone and voids. unique in its ability to measure wood, stones, plastics, shells, rubber, seeds, paper

No uK commercial solutions Not ideal for imaging

liNKEd SECTORS

Astronomy: the microwave background in the Universe provides

evi-dence of the forming of the universe and various other extra-terrestrial microwave sources.

Communication: Many communication protocols operate in the

micro-wave range. An advantage of micromicro-waves over radio micro-waves is that the microwaves have a higher frequency and therefore can encode more information.

Healthcare: There are examples of microwave imaging being used for

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ulTRaSOuNd

Ultrasound uses the transmission and reception of high frequency, low

power ultrasound (pressure waves) to locate foreign bodies by being able to differentiate discontinuities in acoustic impedance by analysis of original and reflected waves. In doing so, can determine composition, structure and physical state.

Ultrasound has been used in food technology for many years [31]. It can be divided into two areas; high frequency, low power and low frequency, high power, the low energy is used for quality assurance and process control and high power ultrasound is an emerging technology area for modification of food (not the focus of this report). For process monitor-ing, recent publications detail the use of ultrasound on canned foods, Refs [32,33]

Impedance matching is far easier for liquids in pipes than discrete ob-jects as better contact can be made between transducer and the object of interest. The transducer can assume various geometries and the pipe itself can act as the transducer as it will always be in contact with the food material - Ref. [34]

Difficult to achieve in practice due to the requirement of contact, al-though there have been proof of principle demonstrations of ultrasound applied to canned foods and cheese, Refs [35-36]. Detection is more difficult in inhomogeneous samples.

liNKEd SECTORS

Whilst high-power ultrasound has many applications in industrial pro-cessing, low power ultrasound is generally used for non-destructive evaluation (NDE) an has many applications:

Healthcare: 2D and 3D imaging are possible in human and animals

us-ing ultrasound and is an attractive technique due to its lack of ionizus-ing radiation and relatively inexpensive and portable equipment.

Industrial processes: used extensively in the aerospace industry for

evaluating cracks and detects in composites and metals. Can also be used for materials such as wood, concrete and cement.

Security: Commonly used in underwater applications as SONAR for

range finding and object location

31. Applications of Ultrasound in Food Technology, Acta Sci. Pol., Technol. Aliment. 6(3), 89 (2007)

32. Detection of foreign bodies in canned foods using ultrasonic testing, International Food Research Journal 19(2), 453 (2012)

33. Online Detection of Contaminants in Packaged Foods with Ultrasound using Signal and Image Processing and Soft Computing, Mittal and Basir, IEEE (2009)

34. Ultrasound in Food Processing, M. J. W. Povey, Springer Books ()

35. Detection of foreign bodies in canned foods using ultrasonic testing, International Food Research Journal, 19, 543 (2012)

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Table 13. Ultrasound usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

Rapid

Non-destructive and on-line low power usage and safety ultrasound can be coupled to liquids in pipes very well. well suited for, large acoustic impedance contrasts, missing items.

well suited for liquids in glass bottles

No commercial solutions good contact required between transducer and object to reduce impedance mismatch, difficult for online systems.

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magNETiC SEPaRaTiON

Magnetic separation can be used to filter out the “tramp” iron that can

find its way into a production from fields or processes. Low intensity magnetic fields are applied to the moving sample of solid or liquid food. The field may be applied from a permanent magnet (high field rare-earth

magnets such as SmCo₅ or Nd₂Fe₁₄B) or electromagnets.

The effectiveness of magnetic separators is reduced in damp food; the technique however is effective in free flowing liquids

Embedded metal contaminants will remain embedded in large, dense food objects. Instead the ideal situation for magnetic separators are small, discrete foodstuffs like nuts, flour etc.

Table 14. Magnetic separation usefulness in the food industry

PROS aNd uSES

CONS aNd limiTaTiONS

Non power consuming, passive detection

Simple to operate

applicable for some metals and can remove objects as small as a few microns.

Can be used well for cereals, nuts, flour

invasive and requires maintenance

Substance must be magnetic Large magnetic fields can be hazardous to health

Not applicable to non free-flowing or damp mediums

liNKEd SECTORS

Industrial processes: such as mining iron, removing useful magnetic

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mETal dETECTiON

In standard metal detection techniques, an RF signal transmitted by the detector is compared with the one received. Non-metallic material passing through the RF field does not distort the RF field. Metal passing through the signal fields however will distort the normal pattern of the electrical fields. Distortion limits can be set to detect very small metal inclusions.

Solutions exist for pipeline metal detectors as RF signals can be used through pipes and metal work. The contamination being present in a liquid phase does not complicate the detection significantly.

As RF signals can penetrate deeply through a medium – large, dense objects can be screened by metal detection techniques.

Table 15. Metal detection usefulness in the food sector

PROS aNd uSES

CONS aNd limiTaTiONS

high level of sensitivity Non-destructive

metals need not be ferrous

Only detects conductive materials

biased towards magnetic materials

many food products are conductive

liNKEd SECTORS

Archeology: both as a hobby and industrially metal detectors are used

to locate metal objects of interest underground.

Military: a very common use of industrial metal detection is in the

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SamPliNg

Sampling techniques involve sampling parts of the production line as

to get a statistical idea of the quality of the entire production line. The sampled section of the line can then be subjected to further off-line tests to check for conformity.

Sampling can be performed for both liquids and particulate objects. Careful consideration must be given to the sampling frequency as under sampling can result in poor coverage and oversampling can be time inefficient and expensive.

See above

Table 16. Sieving and sampling usefulness to the food sector

PROS aNd uSES

CONS aNd limiTaTiONS

Can perform any measurement on the sample once the foodstuff has been samplede

Statistical approaches can easily overlook contaminants

liNKEd SECTORS

Visual inspection, sieving and sampling are used for all industries as at very least a check that automated processes are performing correctly.

Food Report Final Document

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