The Study of Fruit-vegetable and Corn Milk Fermented by Lactic Acid Bacteria
|Keywords||Fruit-vegetable and corn milk fermented by lactic acidbacteria Fermentation technology Storage time Flavor compounds Nutritionalcomponents|
Fruit-vegetable and corn milk fermented by lactic acid bacteria is a kind of food with whole milk powder as raw material, nutrients like fruit, vegetable and grain added. It was fermented with Lactic acid bacteria which gives it nutrition and health function. With unique flavor and nutrient, this kind of mild can not only meet people’s need for balanced nutrition, but has a bright future. The main research and findings were as follows:(1) Fermentation technology study of fruit-vegetable and corn milk fermented by lactic acid bacteria. Some key factors during fermentation process were analyzed through single factor experiment and orthogonal experiment with pH, acidity, viscosity and sensory evaluation as comprehensive evaluation index. The optimum formula of fermentation technology was:fermentation time11h, temperature43℃, milk concentration10%, banana concentration4%, inoculation concentration3/10000, sterilizing condition100℃15min.(2) Changes in physical properties of fruit-vegetable and corn milk fermented by lactic acid bacteria during storage process. Viable count of the probiotics, pH, acidity, viscosity, sensory evaluation, water retention, solid content and texture of fermented milk at different storage time at4℃were analyzed. According to the research, fermented milk with storage time22d keep good quality, total viable bacteria6.8×108CFU/ml, pH4.2, acidity104.5oT, viscosity4481cp, water retention85%, sensory evaluation mark67(total mark80), solid content19%, texture factors:hardness79.72g, adhesiveness33.45g, gumminess63.19g, chewiness2.392mJ, springiness3.86mm, cohesiveness1.411mJ. After22d, all the factors saw a large decrease. Considering all these,22d was determined as the storage time.(3) Flavor compounds study of fruit-vegetable and corn milk fermented by lactic acid bacteria. Changes of several main organic acids such as citric acid, malic acid, succinic acid and lactic acid were analyzed through HPLC. It was showed that the main organic acid in fermented milk is lactic acid with content reaching9.43mg/g. Succinic acid could be detected during the earlier stage of fermentation and disappeared after4h, small quantity of citric acid and malic acid existed also. In order to determine the volatile flavor compounds in fermented milk, SDE-GC-MS was used to analyze the milk and23flavor components were identified, including12hydrocarbons,3ester compounds,2carbonyl compounds,1alcohol compound,1phenolic compound,2sulfides and2furans.2-Heptyl methyl ketone,2-dihydro-5-nonylactone-5-2(3h)-furanon, benzaldehyde, furaldehyde,3-Methylheptane and8-Dodecalactone were the main volatile flavor compounds.(4) Nutritional components study of fruit-vegetable and corn milk fermented by lactic acid bacteria. Indicators like crude protein content, crude fat content, carbohydrate content, mineral content and total energy were detected and computed. The results were as follows:protein content2.88g/100ml, fat content1.95g/100ml, carbohydrate content4.864g/100ml, total energy204.12kJ/100ml, Fe2.2mg/kg, Mg90mg/kg, Mn0.56mg/kg, Cu<0.5mg/kg, Zn≤0.5mg/kg.