Study On Process Technology Of Sayram Ketteki

Sayram yoghurt (Sayram Ketteki), mainly produced in Aksu City, is one of the most popular and traditional fermented dairy products of Xinjiang. The product is produced by natural fermentation process using a certain temperature. The process is completed in about8h to obtain viscous, flexible, white-colored, and sour product. The lactic acid bacterium improve nutritional values, enhance products sensory properties, and help in promoting digestion and absorption. Fermentation process using lactic acid bacterium makes sticky and elastic product. Nowdays mainly two lactic acid bacteria and a yeast have been isolated in Sailimu yogurt:Lactobacillus helveticus MB2-1, Streptococcus thermophilus St. MB5-1and Kluyveromyces marxianus Y51-1. However, optimization of fermentation conditions of the yogurt Sayram Ketteki hasn’t been reported. This article has selected a product in Xinjiang of Chine. A brushed yogurt made by Lactobacillus helveticus. Studies has been conducted to maintain the flavor and texture of this traditional food. The research content and results are described as following:1. Influence of strain combinations on fermentation quality of Sailimu yogurtThe optimal formula of Lactobacillus helveticus fermented yogurt is:inoculum amount5%, fermentation temperature40℃, sucrose addition6.7%to6.8%. Single fermentation yogurt has certain advantages. Under this condition, the production of the drawing yogurt curd time is4.2h, and the viscosity of yogurt is7574. lcp, pH is4.59, and the acidity is81.06°T. The fermented yogurt has a bright and smooth surface, with elastic clot forming sharp edges, whey isn’t presented on the surface. Its sensory assessment is very good. Through orthogonal experiment are determined the optimal parameters for the mix bacteria fermentation of Lactobacillus helveticus and Streptococcus thermophilus. With a inoculum amount5%, bacteria ratio2:1, fermentation temperature40℃, the sugar amount6.7%-6.8%., the yogurt obtained tastes pure and smooth with a marvelous aroma and a good texture, no bad fermentation odor is found. 2. Generqtional culture starter and its stability studiesThe characteristics of yogurt made by Lactobacillus helveticus; ie the brushed sticky texture are proven inherited stably through plasmid by curing experiments and plasmid extraction experiments. Indicators response well in the recycle of the bacteria as well as in the expanded production. Thus Lactobacillus helveticus has a good genetic stability. The theoretical basis for the industrial application of the strains is therefore provied.3. Viable bacteria product shelf-life test and the after-acidification controlWithin the shelf life period, the indicators of Sayram Ketteki are normal, correspond to the national food safety standards for fermented milk GB19302-2010. The yogurt texture maintains well, and the sensory evaluation is good. Yogurt with5mmol/L vanillin added tastes sweet and sour. The highest acidity during shelf life reached approximately115°T.4. Yogurt pasteurization optimizationYogurt optimal pasteurization parameters for yogurt Sayram Ketteki have been determined as20s under75℃. The best formulation of mixed stabilizer of pasteurized yogurt is adding0.4%starch and0.3%gelatin. The sterilization yogurt held hydraulic up to65.47%, has a viscosity of5.958Pa/s and a hardness of5.958N. The shelf life is at least ninety days.5. The flavor compounds of the Sailimu yogurtApply the lactic acid bacteria separated from Sayram Ketteki alone and with yeast, using the solid phase micro extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) in order to detect volatile flavor compounds in fermented milk. Among various flavor compounds, alcohols is the peculiar substances in Sayram Ketteki, alcohols lead a softer, more refreshing taste. The yogurt in Sayram Ketteki doesn’t only contain diacetyl,3-hydroxy-2-butanone characteristic flavor compounds. Compared to the commercial yogurt, esters is the important component to yogurt characteristics of Sayram Ketteki, it affects the flavor of the yogurt. Special, some of the high content of esters offers yogurt more gentle fragrance smells. Its flavor is much better than commercially available yogurt. In addition, its highest concentrations acids can improve the flavor of the product group polygamous to promote yogurt unique sensory flavor formation.Pasteurization of the yogurt affects the flavor substances esters while it affects little on other flavor compounds. This study provides a theoretical and practical basis. for modern technological transformation of traditional industrial production of Sayram Ketteki and pasteurized yogurt industrial production...