| Protein powder is the main ingredient in the food industry. With the development of food industry, a shortage of protein ingredients resources is increasing obviously. Pigskin resources are abundant, cheap and easy to obtain, high protein content in China, which makes it a good raw material of protein. Pigskin protein powder (PSP) was prepared from pigskin according to the following processes:pickled, chopping, drying, crushing, degreasing, et al. The physicochemical properties and functional properties of PSP were researched, and compared it to homemade pigskin gelatin (PSG) and soybean protein isolate (SPI). The PSP as fat substitutes in the application of the cantonese sausage was also reserched. The main results are as follows:1. The chemical composition of PSP are water (13.27%), fat (0.94%, in dry basis), ash (0.16%, in dry basis), protein (96.08%, in dry basis), and the collagen content of PSP accounts for81.90%of total protein. Compared with PSG, PSP better retain the pigskin protein in the material resources, which is a kind of low fat and high protein ingredient. The results of amino acid composition analysis showed that the amino acid composition of PSP is similar to collagen. The results of SDS-PAGE, FTIR and DSC showed that the band distribution of PSP in SDS-PAGE is more concentrated, which compared with PSG. The subunits of PSP and its molecular weight are γ-chain,β-chain (200kDa), α1-chain and α2-chain (100kDa). However PSG are relatively broad molecular weight distribution and a diffuse distribution, mainly concentrated in less than105kDa, this suggests that the molecular weight of the PSP is higher and the structure of the PSP is more complete than PSG. The triple helical structure of collagen in the PSP holds more complete and thermal stability is higher, which compared with PSG The denaturation temperature and denaturation enthalpy value of PSP are81.35℃and779.40J/g respectively.2. The relationship between PSP and pH appears gentle U-shaped curve. The solubility of PSP is low in all pH (2.0-12.0) range. The maximum solubility is15.73%at pH2.0and the minimum solubility is4.32%at neutral (pH7.0). Compared with PSG and SPI, the emulsifying activity of PSP is the best, while the emulsion stability is the worst at pH2.0-10.0. The foaming ability of PSP is the worst compared with PSG and SPI. The water holding capacity is8.24g/g which is between PSG (5.08g/g) and SPI (9.15g/g). Holding oil capacity (13.14g/g), gel property, freeze-thaw stability of PSP are significantly higher than PSG and SPI. The minimum gel concentration of PSP is2%, gel structure features are better than PSG Gel property is the most prominent features of PSP, beneficial to hold water, oil, and the embedding sugar, flavor, etc. Therefore, PSP may not be suitable for application in protein drinks and other liquid food, but is applicable to solid or semi-solid foods.3. Five treatments of cantonese roast sausage were manufactured by replacing0%,33.33%,50%,66.67%and100%pork backfat with PSP. The results indicated that increasing the substitute ration of backfat resulted in the significant increase of water and protein content, texture, a*and b*, but decrease in fat content, cholesterol content and L*. No significant difference in cooking loss, thawing loss, and sensory quality when the fat substitute ration is less than50%. Comprehensive consideration in nutritional properties, processing properties and sensory quality of cantonese sausage, the best substitution rate of fat with PSP is50%. |
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