Studies On Some Physical And Chemical Changes Occuring In Chicken Meat During Frozen Storage

Author : John Charles Frelka
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (99 download)

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Download or read book Changes in Protein-water Dynamics Impact the Quality of Chicken Meat Post Freezing written by John Charles Frelka and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Freezing is one of the most common food preservation methods in the modern world. This method relies on the phase change of liquid water to solid ice, thus reducing the mobility of the system and, in combination with lowered temperature, reducing chemical and biological reactions detrimental to food quality. However, the formation of ice crystals can disrupt the structure of the food matrix, causing loss of quality. Protein-based foods, such as meat, are unique physical systems that have different challenges than fruit and vegetable products. The overall objective of this research was to better understand and measure the physical changes in protein-water interactions in chicken during the freezing process and during frozen storage. The specific objectives aimed to understand the effects of freeze time, storage temperature, and freeze/thaw abuse. The effect of characteristic freeze time (CFT) on the physical quality of chicken meat proteins was explored using typical quality measurements and thermal analyses. CFT ranged from 2.4 to 104 min compared to an unfrozen control. Total moisture, protein extraction, brine uptake, myofibrillar fragmentation index, enthalpy, and gelation were measured after samples were thawed. The total enthalpy as well as relative contributions of each peak were significantly higher after freezing, regardless of CFT. The gelation of salt soluble proteins varied with CFT and the gels had significantly different G’ between the fast and medium freezing CFT. There was a 40% decrease in the final G’ between the unfrozen and slow frozen samples. The effect of frozen storage temperature was explored in an aqueous extract model system and in whole meat systems. The model system was used to study myoglobin oxidation. This study found that under frozen conditions there was a rate acceleration with a maximum around -20°C. This effect was magnified by the addition of NaCl to the system. Whole meat products were tested to determine if this effect was evident in these systems. Quality was measured in whole chicken breasts and ground chicken patties over 3 months of storage. Temperature did not significantly impact any attribute measured. Two freezing rates were tested in patties but did not result in different rates of quality loss. The reverse stability evident in the model system was not observed in the chicken products. The impact of freeze/thaw abuse on the quality of chicken was assessed using magnetic resonance imaging. Drip loss was the only measured attribute that showed significant change with increased freeze/thaw cycles. Physical distribution of water within the chicken breasts was observed in unbrined samples as freeze/thaw cycles increased. There were significant shifts in the proton density distributions from MRI images. Differences were not as pronounced in brined samples, suggesting a level of cryoprotection conferred by the brine. In both brined and unbrined samples, only small differences in T2 distributions were observed. Using NMR micro-imaging significant shifts in T2 distributions were observed in unbrined samples. Water plays a critical role in the structure and quality of chicken meat. This research adds to the understanding of how freezing impacts these critical protein-water interactions.