CONSUMER PERCEPTIONS OF QUALITY: APRICOTS, CANTALOUPES, PEACHES, PEARS, STRAWBERRIES, AND TOMATOES

Consumers are increasing their produce consumption; however, complaints of inconsistent produce quality and improper consumer handling practices could reduce consumer satisfaction with and demand for specific produce items. Seventy to eighty percent of consumers buy cantaloupes, peaches, pears, strawberries and tomatoes at the supermarket; only about half buy apricots at the supermarket. Apricots are not purchased at any location by almost 30% of consumers. Satisfaction with quality is highest for cantaloupes, lowest for tomatoes and apricots. Consumer complaints center around flavor and textural changes which develop in ripening. Both consumer handling practices and fresh product quality contribute to dissatisfaction.     

CONSUMER FOOD SAFETY CONCERNS AND INTEREST IN PESTICIDE-RELATED INFORMATION

Consumer food safety concerns and interest in pesticide related information was measured by personal interviews with 479 consumers in 14 counties in California. Although concern about pesticide safety was noted by almost half of the respondents, nutritional considerations had the greatest impact on food selection criteria. Of those who volunteered pesticide safety concerns, 15% indicated they sought organic produce and 13% said they avoided or reduced produce purchases. In addition to information about the human health effects of pesticide use, consumers expressed high interest in the environmental effects of pesticide use. Consumers currently use television and newspapers as information sources and prefer these to other sources.     

Nutrtional Evaluation of Covalently Lysine Enriched Wheat Gluten by Tetrahymena Bioassay

Tetrahymena pyriformis W was used in a bioassay to evaluate the improvement in protein quality of wheat gluten by enrichment using either simple addition or carbodiimide-mediated attachment of 1% lysine, Nε-acetyl lysine or Nε-benzylidene lysine. Pepsin predjgestion was more effective in solubilizing samples for the assay than papain. All of the enriched samples had relative nutritive values (RNV) approximating that of the casein standard, which had a value of 100, compared to the gluten and acid-solubilized gluten controls which had RNV of 54 and 64, respectively. No difference in the RNV between lysine and the N^E-lysine derivatives, or between covalent attachment and free addition was detected.     

PHYSICOCHEMICAL PROPERTIES OF MUSCLE AND NATURAL ACTOMYOSIN EXTRACTED FROM FARMED ATLANTIC SALMON (SALMO SALAR) STORED AT 4C

Properties of farmed Atlantic salmon (Salmo salar) obtained commercially were studied as a function of storage at 4C for 9 days. While pH increased gradually during storage for both samples, significant differences between samples were noted in water‐binding capacity (WBC) of muscle, as well as surface hydrophobicity (S_o) and sulfhydryl contents of extracted natural actomyosin (NAM). Lower S_owas observed for NAM extracted from muscle stored for 2 days, coinciding with high WBC of the muscle. In contrast, higher S_ofrom 5 to 7 day‐stored samples coincided with minimum extractability and high apparent viscosity of NAM. Reactive sulfhydryl groups were higher at the beginning and end of storage. Generally, WBC of fish muscle was dependent on pH and related to changes in S_oof NAM, while apparent viscosity increased with S_oand disulfide content. The results indicate variability in functional properties of the salmon samples during cold storage, which could be attributed to changes in physicochemical properties of NAM.     

Relationship Between Functional (Fat Binding, Emulsifying) and Physicochemical Properties of Muscle Proteins. Effects of Heating, Freezing, pH and Species

Properties of proteins in salt extracts from beef top round and rockfish fillet changed upon heating and were dependent on pH, freezing, species and sample variability. Generally, heating to >45°C, freezing or lower pH (5.5) decreased dispersibility, increased surface hydrophobicity and slightly decreased sulfhydryl content. Emulsifying and fat binding properties followed parallel trends, being improved under conditions favoring combinations of high dispersibility, hydrophobicity and sulfhydryl content (i.e., heating at <45°C, higher pH, unfrozen). However, high temperature-low pH heating improved fat binding and favored gelation, which might be explained by hydrophobic interactions. Significant (P<0.001) multiple regression models were obtained describing relationships between physicochemical and functional properties of beef and fish proteins.     

Heat-Induced Changes in the Proteins of Whey Protein Concentrate

Three-level fractional factorial experiments were used to study effects of heating conditions (pH, time, temperature, solids content, calcium addition) on whey protein concentrate. Increasing pH and temperature led to lower solubility at pH 4.6 and 7.0, lower sulfhydryl content, higher hydroxymethylfurfural, generally darker color, lower DNBS-available lysine and altered pepsin pancreatin digestion profiles. Mercaptoethanol and SDS demonstrated relative importance of disulfide and hydrophobic bonds on solubility loss. Polyacrylamide gel electrophoresis indicated heat stability of proteose peptones; susceptibility was greatest at pH 8.0, 95°C for β-lactoglobulin and α-lactalbumin, and pH 4.6, 95°C for bovine serum albumin. HPLC gel filtration showed that heating rendered a high molecular weight fraction undissociable by mercaptoethanol.