Effects Of Starter Cultures On The Quality Of Dry Fermented Chinese-Style Sausage

Most of Chinese-style sausages are nonfermented but semi-dry types;however, some previousworks that used some lactic acid bacteria (LAB) as well as Staphylococcus spp. in preparation ofsausages materialized the concept of this project to prepare dry fermented sausage, which wasliterally termed as "dry fermented Chinese-style sausages".In this study, different batches of dry fermented Chinese-style sausages inoculating pure cultureof Lactobacillus caseisubsp.casei-1.001(Lc-1001), Pediococcus pentosaceus-ATCC 33316 (Pp-ATCC 33316), Staphylococcus xylosus-12 (Sx-12) and without starter as a control were prepared. Inanother experiment we prepared sausages inoculating with mixed starter cultures containing Sx-12and LAB in equal proportion. LAB produced lactic acid resulting in decline of pH of sausages;however, too low pH could impair the sensory quality of products, hence the sodium lactate (SL) aspH controlling agent at different concentration (0-3% w/w) was added in raw sausages together withLAB. The processing was done under controlled condition of fermentation and ripening as follow:fermentation at 22±1oC/90-95% RH for 3 days;first ripening at 16±1oC/80-85% RH for 7days andfinal drying at 12±1oC/ 70-75%RH for 14 days.Every batch of sausage samples were analyzed for physicochemical, microbiological,biochemical and sensory qualities. In all batch of samples that treated with different starters showeda rapid decrease in moisture content (about 25%) resulting heavily weights losses (about 50%) andaw (below 0.83) over ripening. Mean time, those sausages added with starters had significantly lower(below 5mg/kg) amount of residual nitrite contents. It is likely seemed that starters except Pp-ATCC33316 did not show antioxidant effect on lipid oxidation during ripening of sausages, rather the finalTBA values increased to the range of 1.04 to 1.46 mg MDA/kg and further increased in mixedcultures added sausages. By contrast, starters particularly LAB caused to suppress the TVBN valuesresulting below 21mg/100g dry matter versus control (25.7 mg/100g dm). The pH decline wasfastest in sausage inoculated with Lc-1.001 resulting lowest pH 4.23), whereas the productinoculated with Sx-12 had the highest pH (5.26). However, mixed cultures showed the mild pHvalues ranged at 4.85 to 4.95. Significant improvement (p<0.05) in red color of sausages particularlyinoculated with starter Sx-12 and mixed starter (Sx-12 + Lc-1.001) have been observed butinsignificant or a very little changes in texture profile of sausages caused by inoculation of suchstarters have been investigated.Increase in non protein nitrogen (NPN), free amino acids (FAA), degradation of severalpolypeptide bands including myosin (200kDa) and actin (43kDa) in myofibrillar as well as otherpolypeptides of molecular weights ~26, 43, 50, 97, and 150 kDa in sarcoplasmic proteins duringripening of dry fermented Chinese-style sausages reflected a strong proteolytic action for starters.Likewise, total saturated fatty acids (SFA) were ranged at 33.04 to 39.67%, whilemonoun-saturated fatty acids (MUFA) at 45.81 to 51.63% and polyunsaturated fatty acids (PUFA) at10.31 to 16.41% of total fat content indicating the highest amount of SFA and least amount ofunsaturated fatty acids in control sample. Meanwhile, the volatiles such as aromatic hydrocarbons,aldehydes, ketones and terpenes were increased in samples that inoculated with Sx-12 and mixedstarter culture (Sx-12+Lc-1.001). Carboxylic acids (over 50% of total volatiles) were found as majorgroup of volatiles in analyzed samples. The entire starter cultures used in this study showed asuppressive action against formation of total biogenic amines during ripening of dry sausages,though mixed starter (Sx-12+Lc-1.001) produced least (289.61mg/kg),while control at most(635.58mg/kg). However, no effects on Tryptamine production have been seen.Three months storage under refrigeration temperature of sausages inoculated with differentstarters caused to increase in moisture, TVBN and TBA significantly, while decrease in pH , redcolor and bacterial ecology. Enterobacteriaceae a group of pathogenic bacteria did not appearthroughout the storage and other bacterial counts (TPC, Micrococcocaceae, yeast and molds andLAB) were decreased by over 1 log unit.By the end of fermentation, pathogenic Enterobacteriaceae were totally disappeared fromsamples that inoculated with starters, whilst they didn't disappear until end of ripening in case ofcontrol. Moreover, starter cultures particularly of LAB and mixed cultures had good inhibitoryeffects on the growth of yeasts and molds during ripening of sausages. Micrococcocaceae countswere affected by pH during lactic fermentation. The LAB, particularly Lc-1.001 showed an intenseantimicrobial action against spoilage as well as pathogenic microorganisms.Sodium lactate at concentration of 1-3% (w/w) resulted some important effects such as pHcontrolling (pH 4.4 to 5.2), antioxidant for fat oxidation (TBA, 0.96-2.13mg MDA/kg) andantimicrobial against aerobic plate counts, yeasts and molds as well as LAB. No effects on color butsignificant effect on texture caused by decreasing in hardness has been investigated in productsadded with SL.From the sensory evaluation results, both of starter culture (either pure or mixed) improved thesensory attributes such as appearance, color, flavor and overall acceptability of products. Sausagesfrom pure starter of Sx-12 and mixed starter (Sx-12 + Lc-1.001), were the best samples for sensoryquality. Although long time storage affected the quality of dry sausages resulting lipid oxidation andpH decline in products, the samples added with starters except Lc-1.001 and control were acceptablein sensory qualities. Sodium lactate at concentration of 2% (w/w) used as pH controlling agent didnot impair the sensory attributes of products. However, higher concentration of SL (3% w/w) couldimpair the sensory quality causing poor after taste value.In conclusion, quality of dry fermented Chinese-style sausages could be improved by inoculatingstarter cultures;particularly pure culture of Sx-12 and Pp-ATCC 33316 and mixed culture (Lc-1.001+ Sx-12). Furthermore, 2% (w/w) of SL seemed to have pH controlling ability against lacticfermentation, which could be applied in processing of dry fermented Chinese-style sausagesinoculated with LAB strains to produce low acidic fermented meat products.