7. PROCESSING AT
7.1 An overview of juice
7.1 An overview of juice
packer operations
Juice packers take in bulk raw materials (con cen - trate and/or NFC), treat them and then fi ll the fi nal product into consumer packages. Some times the distribution of packaged prod ucts is also carried out by the juice packer. Typical operating steps at the juice packer are illustrated in Figure 7.1.
This section discusses the processing steps that take place in a juice packing plant up to the fi lling machine. Packaging activities are cov ered
in Section 9, packaging and storage of or ange juice, and the dis tri bu tion of prod ucts to retail- ers is outlined in Sec tion 10, from juice pack er to consumer.
Capacities of juice packing facilities vary great ly – from small plants producing 5,000 l/h packaged juice to large plants with an output ex ceed ing 150,000 l/h. The larger facilities are built up of mul ti ple process ing and fi ll ing lines. One line of process ing equipment can feed several fi ll ers. Con verse ly, one fi ller can be al ter nate ly connected to several processing lines han dling dif fer ent types of product.
Unlike the fruit processors’ seasonal yet non- stop operation, pro duc tion at juice pack ers is year-round and typ i cal ly involves 2–3 shifts/day, 5–7 days a week. Pro duc tion through put is not uni form throughout the year. Peak output occurs nor mal ly in the run-up to the sum mer months and the Christ mas period.
7.1.1 GENERAL RE QUIRE MENTS FOR JUICE PACKER LINES
Pressure on juice packers from the market is stead i ly in creas ing. They are re quired to supply a wider choice of prod ucts, bet ter qual i ty and con ven ient pack ag ing – at even more com pet i tive prices. Increased prod uct di ver si fi ca tion means small er volumes of each prod uct. In turn, this de mands great er equipment fl exibility and plant de signs that min i mise prod uct losses and down- time when products are changed.
From a plant operation view point, better prod-
Gen tler prod uct treat ment is promoted by proc- ess con trol, which al lows close monitoring and control of op er at ing pa ram e ters, and careful equip ment design.
To supply products at competitive prices re- quires cost-effective op er a tion. High energy re- cov ery that re duc es heating and cooling costs, and minimising product losses in the plant, are two major ways of re duc ing op er at ing costs. To geth er with reducing waste from cleaning pro ce dures, these measures also minimise the im pact on the en vi ron ment.
High-acid products put different demands on process ing equipment compared with low-acid prod ucts like milk. Consideration must be given to the fact that fruit juices differ in viscosity and often con tain par ti cles (pulp). For both aseptic prod ucts and nonaseptically fi lled (chilled) prod- ucts with long shelf life (>20 days), high hygiene standards and safe ty measures are applied to the pasteurisation proc ess and downstream equip- ment in order to pre vent any microbiological recontamination of the prod uct.
The juice packing plant is normally de signed to proc ess and package a range of fruit juices and juice-based still drinks. The equip ment de scribed in this sec tion is not used only for processing or- ange juice. How ev er, com ments made regarding equip ment re quire ments and per form ance relate to orange juice.
7.1.2 PROCESS LINES
The process line from the reception of raw ma- te ri al up to product at the fi ller in volves a number of process steps. Which steps are re quired de pend on the type of raw material and product to be pro- duced. Figure 7.2 illustrates the process steps for production of orange juice starting from fro zen or ange con cen trate as raw material (Lines 1 and 2). In gre di ent prep a ra tion for the pro duc tion of or ange nec tar and fruit drinks is also in clud ed. In lines 3 and 4, the raw material is NFC.
Concentrate storage and prep a ra tion
Concentrate received in tank cars is pumped into large storage tanks. The stor age area is re frig - er at ed or the tanks are equipped with cool ing jackets. The con cen trate should be kept at less than 0 °C. Concentrate received in drums is placed in fro zen stor age.
From the storage tanks, con cen trate may be pumped directly to the blending area for re con - sti tu tion with water. If con cen trates of different or i gins or fruit types are to be blend ed, this may take place in a sep a rate tank prior to dilution with wa ter. Concentrate in drums is warmed up to –5 °C or higher before it is poured or pumped out. Water treatment
the qual i ty of wa ter sup plied to the plant. Treatment meth ods com mon ly used in clude sand fi l tra tion to remove in sol u ble sol ids, ac tive car bon fi l tra tion to re move col our, and mem brane fi l tra tion to re duce dis solved salts (and organic mat ter). Ion-ex change tech niques may be used to sof ten the water or re duce its al ka lin i ty. When there is high water con sump tion in a plant, e.g. during start-up and clean ing cy cles, treated prod uct wa ter is routed to a buffer tank to en sure a suf fi cient sup ply. Batch blending
The re con sti tu tion step, referred to as the blend- ing step, is carried out batchwise in Line 1. The con cen trate is di lut ed with wa ter in large ag i tat ed tanks. A batch is pre pared in one tank while prod-
LINE 1
LINE 2
Water treatment
Concentrate storage and prep a ra tion
Concentrate storage and prep a ra tion
Drink preparation
Batch blending
In-line blending 7.1 An overview of juice packer operations
(and sugar solution for nectars and fruit drinks) are added in the batch tank along with the con- cen trate. Oth er in gre di ents may be add ed directly to the batch tank but are often pre pared as a pre- blended mix ture in the drink preparation area. In-line blending
In Line 2, treated water and concentrate (and oth er ingredients) are fed continuously to the in- line blending system and mixed en route to the pasteuriser. The critical parameter, usually Brix of the fi nal product, is monitored con stant ly. Flow rates of the respective components are adjusted by the control system to main tain the target Brix
Pasteurisation and deaeration
In the pasteuriser, juice is heated in tu bu lar or plate heat ex chang ers to pas teur i sa tion tem- per a ture (80–95 °C), which is maintained as the product pass es through the holding cell. The juice is then cooled to fi lling tem per a ture and routed to the fi ller. Free air and dis solved ox y gen are removed from the juice in a deaerator.
Most of the heat used is re cov ered from cool ing pasteurised juice and ad di tion al en er gy is sup plied by cir cu lat ing hot wa ter heat ed by steam. During clean ing, start up, and any op er at ing fail ure, the fl ow is recirculated over the pasteuriser.
Cleaning in-place Pasteurisation Pasteurisation Aseptic buffer Aseptic buffer Filling
Fig. 7.2 Processing lines using concentrate as raw material.
7.1 An overview of juice packer operations
Aseptic buffer
In most cases pasteurised product goes directly to the fi ller from where any overfl ow is re turned to the pasteuriser. A buff er tank ensures that vari- ations in fi ller oper ation do not af fect up stream process ing, and that continuous ad just ment of pres sure and fl ow can be made to suit the fi lling ca pacity. Buffer capacity is re quired for certain types of fi ller. Buff er tanks should be of asep tic de sign to avoid recontamination of prod uct. Filling
One pasteuriser system can feed product to one or several fi llers. The same type of pasteuriser yield ing commercially sterile prod uct is used for both asep ti cal ly fi lled juices and nonasep tic juices in tend ed for long shelf life under chilled conditions. A dif fer ent pasteuriser design is used for hot fi ll ing.
Drink and nectar preparation
Sugar supplied to a plant in liq uid form can go di rect ly to on-site buffer stor age, whereas gran u lar sug ar has to be dissolved in water to obtain a so- lu tion of specifi ed Brix con tent. Small quan ti ties of ingredients for the pro duc tion of nectars and fruit drinks may be premixed before routed to the blend ing sec tion. Sugar dis solv ing and in gre di ent mixing are usu al ly car ried out batchwise. Cleaning-in-place
Effective cleaning of all process line equipment is essential for good operational results. The clean ing unit supplies the required so lu tions and controls the cleaning sequences. A large cen tral unit may clean the whole plant, or there may be locally placed units for cleaning dif fer ent parts of the line.
NFC frozen storage Thawing and crushing Blending and buffer
Blending and buffer
NFC chilled storage Juice emptying
7.1 An overview of juice packer operations
LINE 4 LINE 3
Automation and process control
Operators control individual processing units via panels located near the equipment or from a central control room where the whole process line is supervised. The automation system may supply on-line information to man age ment along with regular reports, and may be di rect ly linked to the production scheduling de part ment.
NFC storage
Processing lines using Not From Concentrate (NFC) as raw material are shown in Lines 3 and 4. Frozen NFC, usually in 200 l drums, is stored at –18 °C. Aseptic bulk NFC, typically in aseptic storage tanks or aseptic bag-in-box con tain ers, is stored at 0 °C or higher.
NFC preparation
Solid frozen NFC is liquefi ed before process ing. Rapid thawing is achieved by initial heating in a tun nel followed by tipping the drum con tents into an ice-crusher. The ice slurry is then melted in a tu bu lar heater.
Juice in tanks and aseptic bags is liquid and can be pumped directly to buffer tanks. Asep tic bags are emptied via a hose pump inserted into the top of the bag, or with a pump connected to the emptying spout at the bottom of the bag.
Liquid NFC goes to buffer tanks. Here juice of different origins may be blended and pulp add ed. Pasteurisation and other downstream process- ing steps are carried out in the same way as for reconstituted juice shown in Lines 1 and 2.
Fig 7.3. Processing lines using NFC as raw material. Pasteurisation
Aseptic buffer
Aseptic buffer
Filling
7.1 An overview of juice packer operations