Study on Domestic Goat Milk for Making Fresh Cheese and Fermented Whey

• Main Authors: Jing-Jung Lin, 林京蓉
• Other Authors: Tsai-Fuh Tseng
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/65572598911467950852

碩士 === 國立嘉義大學 === 動物科學系研究所 === 99 === The purpose of this study was to study on making fresh cheese from domestic goat milk and fermented whey. Test 1 was to compare the qualities of fresh goat cheese with different fat contents. Three fresh goat cheeses made by whole goat milk, low fat goat milk and skim goat milk. The milk was pasteurized and then cooled, a mixed strain culture of Lactobacillus acidophilus (BCRC 17064) + Bifidobacterium longum (BCRC 11847) (1:1) was added to the milk with 15% and was made the fresh goat cheese. After the cheese was made, the approximate composition analyzed for moisture, crude protein, milk fat and ash; and the other measurements such as moisture, pH value, titratable acidity, hardness, color, lactic acid bacteria count, fatty acid composition, amino acid composition, Sodium Dodecyl-Sulfate Poly-Acrylamide Gel Electrophoresis (SDS-PAGE) and sensory evaluation were determined. The results showed that lower protein content in cheese product (P<0.05) in fresh goat cheese made by higher fat content in raw milk. At 4℃ cold storage for 4 weeks, the moisture, pH value, titratable acidity, color and lactic acid bacteria count of all treatments of fresh cheeses showed no significant difference but the fresh goat cheese made by low fat goat milk was of the biggest hardness; the fresh goat cheese made by whole goat milk was of most fatty acid content and the fresh goat cheese made by skim goat milk has the less amino acid content. With SDS-PAGE, there was shown that αs2-casein, β-casein and κ-casein were decreased at week 4 in all treatments. On sensory evaluation, there were no significant differences among treatments. Test 2 was to investigate the effect of post- pasteurization of fermented goat whey. Fermented goat whey were made by the whey removing from fresh goat cheese and added with 25% sugar, then pasteurized and cooled, a mixed strain culture of Lactobacillus acidophilus (BCRC 17064) + Bifidobacterium longum (BCRC 11847) (1:1) was added to the whey at 5%, incubated at 37℃ for 6 hours and then storaged at room temperature for 8 weeks as control group; re-pasteurization with 80℃for 20 minutes and then storaged at room temperature for 8 weeks as contrast post-pasteurization group. During storage, pH value, titratable acidity, water activity (aw), lactic acid bacteria count, amino acid composition, SDS-PAGE and sensory evaluation were determined. The results showed the titratable acidity, L value and b value of post-pasteurization group was significantly lower than control group (P<0.05), and the aw is significant higher than control group (P<0.05). The amino acid content of both treatments were increased with storage. With SDS-PAGE showed that there was no change on β-lactoglobulin and α-lactalbumin at week 8. On sensory evaluation, the overall acceptability of post- pasteurization group with dilution rate 1:1 and 1:2 was significantly higher (P<0.05).