| As a traditional meat product, fermented sausage has been popular in Europe for a long time. However, the consumption of it in China is very low due to diet culture differences. Therefore, to develop a kind of leisure fermented sausage suited for Chinese taste will have a promising market. In this paper, the direct-vat-agent commercial starter cultures were used for sausages fermentation, ingredients and processing conditions were optimized, a feasible method for oil leakage issue in baking process was proposed and changes during processing and the stability during storage were also studied.Chr-Hansen F-1(Pediococcus pentosaceus and Staphylococcus xylosus) starter culture was adopted based on sensory evaluation and acidification rate. The total number of lactic acid bacteria and micrococcus could reach 109cfu/g and 106cfu/g respectively and the product's final pH was 4.90-5.10 after fermentation for 16h by 25g/100Kg F-1. The product had appropriate sourness, rich aroma and excellent sensory properties. Through the response surface optimization, the best processing conditions of fermented sausage were determined: fermentation temperature 25.3℃, fermentation time 23.4h, baking temperature 55℃and baking time 7.8h.The ingredients amount was optimized and the best recipe was as followed:fat 200g, muscle 800g, salt 19.2g, sucrose 15.0g, glucose 12.3g, sodium nitrite 0.1g, sodium erythorbate 1.2g, compound phosphate 2.1g. Spices, such as star anise, fennel, cinnamon, allspice, have no affect on the final pH of sausages, but Chinese prickly ash, pepper and liquorice had inhibition effect on acidification.Studies showed that adding gelatin could lower the hardness value of the product, adding more than 1.2% xanthan gum could improve the hardness value, adding 0.6% carrageenan could improve both the hardness and springness value. Although KM and KH could increase moisture content and aw, hardness value and sensory qualities would decrease. Emulsifiers had obvious effect on reducing oil leakage. SPI and WPC could significantly improve the texture properties of fermented sausages with higher hardness and springness value. The results showed that adding 2.0% SPI could prevent oil leakage most effectively.The physical and chemical indicators of fermented sausage significantly changed at different processing stages. pH dropped from 5.85 to 4.93 after fermentation and up to 5.13 after baking; Lightness index (L*) increased while redness (a*) and yellowness (b*) decreased; Moisture content decreased from 48.40% to 36.16%; aw decreased from 0.937 to 0.870. The volume of free amino acids in fermented sausage increased during processing:the content of total free amino acids increased by 25.82mg/100g dry matter (DM) with a volume of 312.85mg/100g DM after fermentation and by 87.72 mg/100g DM with a volume of 374.72mg/100g DM after baking.The volatile flavor substances of fermented sausages were analyzed by GC-MS, mainly including formaldehyde, naphthalene, alkanes, esters, acids, ketones, furans, pyrazine, etc.. Types and contents of volatile flavor substances had great changes during processing. Types of flavor compounds increased from 37 to 53 after fermentation while reduced to 43 after baking.Storage temperature had an obvious effect on the quality of fermented sausages. Storing at 37℃accelerated quality deterioration. The sensory quality, color and texture properties were relatively stable at room temperature after 105 days'storage. Low temperature storage (4℃) was more conducive to the product quality. The results of microbial detection showed no mold and yeast growth. It was illustrated that the product had a good safety and a long shelf life. |
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