14. Ease of swallowing (Scale: easy to hard.)
15. Residual particles Amount of loose particles left in mouth after swallowing. 16. Toothpack Amount of material packed in and around teeth. (Scale:
none to much.)
17. Mouth-coating Amount of moisture and fat coating the oral cavity after swallowing. (Scale: low to high.)
toothpack. Needless to say, this is significantly more than a single force shear value and adds to the broad spectrum of attributes that we term “texture.” The impact and comp- lexity of juiciness are evident in the panel results.
Ground poultry meat texture studies
A series of studies published in the late 1970s and 1980s24–26characterized the texture of poultry products made from ground and comminuted meat with various ingredients. All three studies utilized both sensory panel methods and instrumental texture measurements. A wide range of quality attributes was evaluated (proximate composition, water-holding capacity, color, rancidity, and cook loss). In one of the studies,24 use of mechanically deboned poultry meat as the meat source (with and without skin) in conjunction with two levels of structured protein fiber (15 and 25%) was evaluated by a 5-member trained panel using the QDA technique. In addition, a scale to reflect overall impression of the products was included.
In another study,25six patty formulations containing different amounts of mechanically deboned broiler meat (MDBM), hand deboned fowl meat (HDFM), and structured protein fiber (SPF) were characterized for proximate composition, rancidity (measured as thiobar- bituric acid or TBA values), color (Hunter L, a, b values), force to shear (W-B), and sensory properties. Sensory properties were evaluated using QDA. As the level of MDBM decreased, moisture and protein contents, lightness (L values), and shear values increased correspondingly; fat content, redness (a values), and TBA values decreased. Sensorially, as the level of MDBM decreased, the products were perceived as being lighter, more chewy and elastic, and less juicy. Based on the instrumental and sensory data, the authors noted that interchangeable ratios of 40:60/60:40 MDBM and HDFM could be incorporated with SPF to yield products of good quality. These multiple point results illustrate the benefits of integrating instrumental and sensory analysis to arrive at decisions involving finished product quality. A spider-web diagram illustrating part of the results is shown in Figure 7.9.
Figure 7.9 A spider-web diagram of sensory evaluation of mechancally deboned broiler meat (MDBM) and hand deboned fowl meat (HDFM). (Adapted from Lyon, B.G., Lyon, C.E., and Townsend, W.E., J. Food Sci., 43, 1656, 1978.)
Data points are placed on the various lines representing each attribute. The center repre- sents a value of “0” and the values increase away from the center point. The differences in attributes such as outer appearance, chewiness, elasticity, particle size/shape, and over- all impression are easily noted. In this example, the combination of 40% MDBM: 60% HDFM was superimposed on the 100% MDBM patty product for visual comparison of attributes. In yet another study, Lyon et al.26used TPA to determine differences between mixed and flake-cut MDPM in patties containing either 15 or 25% SPF. The six-member trained panel also evaluated juiciness using a seven-point intensity scale. Positive, significant cor- relation coefficients between instrumental and sensory measures of hardness, springiness, and chewiness indicated that the Instron and the panel were in good agreement.
Color
Color is very complex and is a major component of appearance in poultry meat or pro- ducts. Instrumental methods to measure color of an object are based on a light source and a detector. Objects absorb and reflect light wavelengths that are detected by an instrument or an observer. Results of instrumental detectors have little meaning unless validated by the human observer. Therefore, numerical values provided by colorimeters are almost always associated with a color/appearance term in order to understand the meaning. For example, “lightness” is associated with “L values,” “redness” with “a values” and “yel- lowness” with “b values” when an “Lab” color coordinate system is used. A typical col- orimeter used in research and quality assurance is shown in Figure 7.10.
Fletcher27reviewed poultry meat color, color measurements, methods used to measure color, and summarized color defects associated with poultry. The review of meat color covered raw meat and many of the factors that affect meat color such as sex, age, strain, processing procedures, cooking temperature, and freezing. Of particular significance at the present time are the factors that influence “pinking” of breast meat. The significance from both quality and safety standpoints is the assumption of insufficient cooking time/tem- perature. This is a problem with immediate economic ramifications (returned shipments of
cooked product). Other specific color defects include the relationship between lightness (paleness) and poor protein functionality,28and the consumer objection to color variation between meat pieces in a retail package.29
Flavor
Flavor analyses of poultry or poultry meat involves methods to extract compounds that are assumed to contribute to aroma. Taste is usually associated with the basic solutions of salt, sweet, sour, and bitter, while aroma is associated with stimulation of receptors in the nasal cavity by volatiles released by foods. Instruments that separate compounds and indicate their concentrations include gas chromatography (GC), high pressure liquid chromatogra- phy (HPLC), and sensing devices referred to as “electronic noses.”
GC and HPLC are methods that separate extracts of the food into individual com- pounds. Although individual compounds and classes of compounds have been identified, they must be related to sensory response by descriptors. Sensory descriptors determined by a trained panel for evaluation of cooked chicken were developed by Lyon30(Table 7.4). Farmer31listed as many as 34 main compounds that are considered to be key components of cooked chicken flavor. Taken alone, the individual compounds do not always exhibit the aroma of individual perceived aromas from the samples. For example, 2-acetyl-pyrroline, a key odor compound in cooked poultry meat, is described as “popcorn.” Re-combining certain chemicals to create an aroma-specific character note is not always successful. Sensory panels can tell the difference.
The electronic nose is a name given to instruments comprised of arrays of materials (metal oxides, conducting polymers) that record an electrical charge or resistance response when a stream of volatiles is passed over them. Several sensors of varying materials give varying responses so that a pattern emerges for a given sample. Key to the instruments is
Table 7.4 Terms Used for Profiling the Taste and Aroma of Fresh and Reheated Chicken Meat
Descriptive term Definition
Aromatic, taste sensation associated with:
Chickeny Cooked white chicken muscle
Meaty Cooked dark chicken muscle
Brothy Chicken stock
Liver, organy Liver, serum or blood vessels
Browned Roasted, grilled or broiled chicken patties (not seared, blackened or burned)
Burned Excessive heating or browning (scorched,
seared, charred)
Cardboard, musty Cardboard, paper, mold or mildew; described as nutty, stale
Warmed-over Reheated meat; not newly cooked nor rancid, painty
Rancid, painty Oxidized fat and linseed oil Primary taste associated with:
Sweet Sucrose, sugar
Bitter Quinine or caffeine
Feeling factor on tongue associated with:
Metallic Iron or copper ions
analysis of data by multivariate statistical programs that can detect pattern differences and also develop algorithms that can later recognize this pattern as belonging to a certain sam- ple. Supposedly, the technique is based on how a stream of volatiles will pass across the receptors in a human’s nose, detect the differences, and attach a recognition to the pattern for future identification.