| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 97 === Thai fermented pork sausage (nham sausage) is a traditionally fermented food that made from ground pork, sliced pork skin, cooked rice mixed thoroughly with garlic, pepper, salt, bird chilli, nitrate-nitrite. And then, the sausage was packed in either banana leaves or cylindrical plastic bags for 3 to 5 days. The fermentable carbohydrates (cooked rice) are used for microorganisms to produce lactic acid and organic acids that contributed to unique flavors and textures, but it also depend on contamination with wild strains of lactic acid bacteria and nitrate-reducing bacteria. Since most nham sausage are consumed without further cooking, it is important to proper fermentation for ensuring the products safety. Therefore, starter cultures and carbon sources that used in nham formulation are two important factors to affect product quality and safety. The use of anka rice to improve the color properties of fermented sausages also would be studied in this research.
In experiment I, starter culture and different levels of cooked rice were used to produce nham sausage, and then the microbiological, chemical and physical properties were determined to evaluate the quality and safety of the products. The results showed that cooked rice concentration and storage time didn’t affect lactic acid bacteria and total plate counts (P>0.05), but found a lower pH in nham sausage (P< 0.05) with high percentage of cooked rice. It also found increasing in L and b color during storage time (P<0.05). Moreover, treatment with 5% (11.33-12.35) of cooked rice had the highest a value than other treatment (P<0.05). However, a value of all samples weren’t stable during the whole storage time except 7% of cooked rice. In this experiment, it was found that 10% of cooked rice in nham sausage had significantly lower water released value than other treatments (P<0.05), but not significantly different within 1%, 3%, 5% and 7% of cooked rice. Texture in this study showed unable results in all treatment, due to the nham sausages didn’t have uniform structure. However it could find that treatment 7% of cooked rice was lower in all textural values. The data of sensory test showed that all treatments could obtain high significantly overall accept score by the panelists, excepting of 1% of rice treatment (P<0.05).
In Experiment II, starter culture and 7% of cooked rice and different levels of anka rice were used to produce nham sausage, and evaluated the microbiological, chemical and physical properties. Both of level of anka rice and storage time factors weren’t significantly different in the chemical contents, total plate counts and pH value (P>0.05). Whereas, mold and yeast counts in each treatment were changed during storage period (P<0.05) and showed maximum increased in 3 days of storage. The higher level of anka rice resulted in the decrease in nitrite concentration and L value, but the increase in a and b values (P<0.05). The change of levels of anka rice and storage time had no marked effect on textural properties of nham product. However, addition anka rice had effects on appearance and color scores (P<0.05), showed lower scores with higher levels of anka rice.
Overall conclusion, 7% of cooked rice is suitable for use in nham sausage production. Because in this treatment was obtained final pH value at 4.60 for fermentation which is a point for safety of lactic acid fermented foods, and be kept stable in redness color during 7 days of storage. However, 0.25% of anka rice obtained the highest in color scorces, which is suitable level for nham product.
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