EFFECTS OF PULSED ELECTRIC FIELDS (PEF: 1?2 KV/CM, 20 ?S) USED ALONE AND COMBINED WITH CARBON DIOXIDE (CO2: 70%) AND HIGH HYDROSTATIC PRESSURE (HP: 150 MPA, 5 MIN) ON THE PHYSICOCHEMICAL PROPERTIES AND MICROBIOLOGICAL SHELF LIFE OF COHO SALMON UNDER PRE- AND POST-RIGOR CONDITIONS WERE STUDIED DURING REFRIGERATED STORAGE (25 DAYS). THE PEF + CO2 + HP TREATMENTS REDUCED COLOR CHANGES IN PRE-RIGOR MORE THAN IN POST-RIGOR SALMON. TEXTURE CHANGES OF PRE- AND POST-RIGOR SALMON DIFFERED BETWEEN UNTREATED AND TREATED SALMON. COMBINED TREATMENTS ALSO EFFECTIVELY REDUCED THE PROTEASE AND LIPASE ACTIVITY OF PRE-RIGOR SALMON. COLLAGENASE ACTIVITY OF POST-RIGOR SALMON REMAINED LOW IN ALL TREATMENTS. PRINCIPAL COMPONENT ANALYSIS SHOWED A CLEAR DIFFERENCE BETWEEN PRE- AND POST-RIGOR STATES IN THE EVALUATED PARAMETERS; HOWEVER, MICROBIOLOGICAL SHELF LIFE INCREASED WITH PEF + CO2 REGARDLESS OF THE RIGOR CONDITION. IN CONCLUSION, COMBINED PEF, CO2, AND HP TREATMENTS CAN IMPROVE SALMON QUALITY DURING REFRIGERATED STORAGE AND THUS EXTEND ITS MICROBIAL SHELF LIFE.

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

THE EFFECT OF HIGH HYDROSTATIC PRESSURE (HHP) CONDITIONS AT TWO PROCESSING STAGES (300 MPA/5 MIN AFTER TUMBLING AND 600 MPA/3 MIN APPLIED TO THE FINAL PRODUCT) AND SODIUM REDUCTION (UP TO 50%) ON THE PHYSICOCHEMICAL PROPERTIES AND SENSORY AND MICROBIOLOGICAL QUALITY OF READY-TO-EAT (RTE) CHICKEN BREASTS WERE STUDIED. THE MICROBIOLOGICAL SHELF LIFE OF RTE CHICKEN BREASTS WAS ALSO ESTIMATED. THE NACL WAS PARTIALLY REPLACED WITH KCL (25%?50%), WHICH INCREASED (P < 0.05) COOKING LOSS AND HARDNESS OF CONVENTIONAL RTE CHICKEN BREASTS. HHP PROCESSING SIGNIFICANTLY REDUCED COOKING LOSS AND HARDNESS AND IMPROVED THE SENSORY ATTRIBUTES OF SODIUM-REDUCED RTE CHICKEN BREASTS COMPARED WITH CONTROLS. HHP EXTENDED THE MICROBIOLOGICAL SHELF LIFE OF SODIUM-REDUCED RTE CHICKEN BREASTS BY MORE THAN 60 DAYS. BASED ON THEIR PHYSICOCHEMICAL PROPERTIES AND SENSORY QUALITY, THE UNPRESSURISED RTE CHICKEN BREASTS REDUCED NACL UP TO 25%, WHILE PRESSURISED RTE CHICKEN BREASTS REDUCED UP TO 50%. HHP CONTRIBUTES TO DEVELOPING SODIUM-REDUCED RTE CHICKEN BREASTS WITH ENHANCED PRODUCT QUALITY AND MICROBIOLOGICAL SAFETY.

THE QUICKLY EXPANDING FIELD OF PLANT-BASED FOOD, GENERALLY USES PROTEIN CONCENTRATES OR ISOLATES AS PROTEIN SOURCE. IT IS HOWEVER NOT CLEAR TO WHAT EXTENT THE INTENSIVE PROCESSING OF THESE RAW MATERIALS AFFECTS THEIR DIGESTIBILITY. WE HERE REPORT ON THE IN VITRO GASTRIC DIGESTIBILITY OF THE STRUCTURES PRESENT IN UNHEATED AND HEATED DISPERSIONS OF SPRAY-DRIED PROTEIN ISOLATES OF SOYBEAN AND YELLOW PEA. UNHEATED DISPERSIONS CONSIST PRIMARILY OF INSOLUBLE INDIVIDUAL SPRAY-DRIED PARTICLES, AGGLOMERATES OF THESE AND ONLY A SMALL FRACTION OF SOLUBLE PROTEIN. PEPSIN ACTIVITY WAS FOLLOWED IN REAL-TIME THROUGH MICROSCOPIC OBSERVATIONS, SHOWING THE DISASSOCIATION OF AGGLOMERATES AND INWARD-BREAKDOWN OF INDIVIDUAL PARTICLES, WHICH ARE OTHERWISE STABLE AT GASTRIC PH AND IONIC STRENGTH. THIS DEMONSTRATES THAT SOLUBILITY IS NOT NECESSARILY AN INCENTIVE FOR GASTRIC PROTEIN DIGESTION. HEATING DOES NOT SIGNIFICANTLY AFFECT THE OVERALL DIGESTIBILITY OF PROTEIN ISOLATE DISPERSIONS. NEVERTHELESS, HEATING DISRUPTS THE STRUCTURE OF SPRAY-DRIED PARTICLES, INCREASING THE AMOUNT OF SMALLER AND BETTER DIGESTIBLE PARTICLES THAT REMAIN SUSPENDED AFTER CENTRIFUGATION. CONVERSELY, HEAT-INDUCED AGGREGATES REMAIN IN THE PELLET AND ARE UP TO 50% LESS DIGESTIBLE THAN THEIR UNHEATED COUNTERPARTS. THIS IMPAIRED DIGESTIBILITY IS COUNTERBALANCED BY A REDUCED PROPORTION OF POORLY-DIGESTIBLE SPECIES IN THE FULL SYSTEM (UP TO 11% FOR SOY AND 23% FOR PEA).

THIS STUDY AIMED TO EVALUATE THE EFFECT OF HIGH PRESSURE IMPREGNATION (HPI) (PRESSURE: 350, 450, AND 500?MPA; TIME: 5 MIN; OSMOTIC SOLUTION: 15% NACL) AS A PRETREATMENT TO THE DRYING PROCESS OF ABALONE SAMPLES (TEMPERATURE: 60°C) AND SUBSEQUENT EVALUATION OF PHYSICOCHEMICAL PROPERTIES THEREOF. THE PROTEIN CONFORMATIONAL CHANGES OF HPI-DRIED SAMPLES WERE EVALUATED BY FOURIER TRANSFORM INFRARED (FT-IR) SPECTROSCOPY. THE MOLECULAR WEIGHT PROFILE AND AMINO ACID COMPOSITION WERE DETERMINED. THERMAL ANALYSIS WAS PERFORMED BY DIFFERENTIAL SCANNING CALORIMETRY (DSC). PROCESS DRYING RATES WERE REDUCED UP TO 33%, AND DRIED ABALONES HAD LOWER MOISTURE CONTENT AND WATER ACTIVITY AS THE PRESSURE LEVEL INCREASED. IN ADDITION, LESS DEGRADATION EFFECTS WERE FOUND IN AMINO ACID COMPOSITIONS. IN THE ?-SHEET STRUCTURE, HPI-ASSISTED DRYING PROCESS CAUSED PARTIALLY FOLDED CONFORMATIONS AT 350 AND 450?MPA, AND AGGREGATION AT 500?MPA. A COMPACTED STRUCTURE WAS IDENTIFIED AS PRESSURE INCREASED (350 ? 500?MPA), CONFIRMING THAT THE STRUCTURE OF ABALONE MUSCLE TREATED WITH HPI-ASSISTED DRYING DIFFERED SIGNIFICANTLY FROM RAW MATERIAL. THE RESULTS PRESENTED IN THIS RESEARCH COULD SUPPORT THE POTENTIAL APPLICATION OF HIGH HYDROSTATIC PRESSURE TREATMENT AS COMBINED TREATMENTS FOR OTHER COMPOUND IMPREGNATION UNDER HIGH PRESSURE. IN ADDITION, HPI TECHNOLOGY COULD BE USED TO ENHANCE THE QUALITY PROPERTIES OF DRIED ABALONES AND DRIED MARINE PRODUCTS OF THE AQUACULTURE AND FISHERY INDUSTRY.