Gelation and Biochemical Properties of Mechanically Separated Pork
Date
2019-07-29
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-3108-5719
Type
Thesis
Degree Level
Masters
Abstract
Mechanical separation of pork serves to recover more protein from a carcass but may compromise texture of processed meat products. To increase utilization of mechanically separated pork (MSP) as a partial substitute of regular pork in comminuted meat products, it’s critical to understand the physicochemical and biochemical properties of MSP.
The first objective for this study was to investigate the chemical composition, physicochemical and gelation properties of MSP and the effect of chilling rate and frozen storage on properties of MSP. MSP from pork picnic bones had lower collagen content, higher pH value, and was higher in calcium and iron content (p<0.05) than pork picnic (PP). The natural actomyosin (NAM) from MSP showed decreased viscoelasticity. At the cellular level, the MSP had highly disrupted structure with randomly oriented, curved and twisted myofibrils. The myosin heavy chain (MHC) was partially degraded after the mechanical separation process as confirmed by immunoblotting with MHC antibodies. The ratio of myofibrillar protein to sarcoplasmic protein decreased (p<0.05) in MSP compared with PP. With the heat and pressure generated through the process, MSP had higher (p<0.05) lipid oxidation level throughout the frozen storage period (1 to 13 months) compared with ground PP.
The second objective was to evaluate the potential utilization of MSP as a substitute of regular pork in bologna processing and the effects of initial chilling rate and -18 °C frozen storage on gelation properties. Substitution of 7.5% MSP didn’t lead to a significant negative influence on the texture of a low fat (14%) bologna product. The bologna with 15% MSP was dark red, soft and mushy in texture with very low hardness and chewiness, which is not acceptable. The initial chilling rate and the length of frozen storage didn’t play a significant role in the physicochemical properties of MSP and bologna formulated with 7.5% or 15% MSP.
Overall, the results indicated that the mechanical separation process generated highly disrupted pork muscle cell ultrastructure, degraded MHC, and compromised gelation properties of MSP. Following up to 13 months of frozen storage, the colour of MSP was slightly deteriorated and lipid oxidation increased. The approach to chill MSP more quickly didn’t help preserve the gelation ability significantly and typical delays in chilling also had no effect. The replacement of MSP at 7.5% level didn’t negatively influence bologna texture significantly, but 15% replacement did.
Description
Keywords
Mechanically separated pork, Gelation, Lipid oxidation, Myosin heavy chain, Protein degradation, Chilling rate, Frozen storage, Bologna
Citation
Degree
Master of Science (M.Sc.)
Department
Food and Bioproduct Sciences
Program
Food Science