| Lotus is characteristic agricultural resources in China. As the nutritional value and health efficacy is gradually recognized and valued, it is worthy of being further researched developed and used.In this study, lotus(Hunan cultivars) was firstly used as the main material. By germination technology, the contents of protein and other nutrients in lotus were increased. With such germinated lotus, milk powder was processed into yogurt finally. At the first step, optimize the strain combination for fermentation of lotus seed yogurt,and then fix the basic processing parameters with or without the lotus seed germination procedure for making lotus yogurt. Secondly, based on the physical and chemical analysis of these two kinds of lotus yogurt, their qualities was compared to discuss the application of HACCP in the production of lotus seed yogurt and provide reference for deep processing and industrial production of lotus seed. The main findings were as follows:1. Study on the optimum strain combination for fermentation in starter cultures:Under the single factor test and comprehensive test, the effects of Lactobacillus bulgaricus, Streptococcus thermophilus and Bifidobacterium on quality of lotus seed yogurt was evaluated. It was found that the optimal proportion in yogurt starter cultures:Lactobacillus bulgaricus,Streptococcus thermophilus, Bifidobacterium=1:3:2.2. The exploration of technological parameters of producing yogurt:Fuzzy mathematical comprehensive sensory evaluation parameters, such as coagulation time, acidity, PH and viable count of lactobacillus, were applied to optimize the important influencing factors for producing yogurt with un-sprout lotus seed and yogurt with sprout lotus seed by orthogonal test. The optimal technological conditions of yogurt with lotus seeds and yogurt with sprout lotus seed were as follows:the proportion of lotus seed paste and restoration milk (v:v) was 1:2; the inoculation quantity was 4%; the fermentation time was 4 h at 42 ℃, the addition of sugar was 6%. Under these condition, the yogurt texture was good, sweet and sour moderate, without whey separation.3. Comparison of product quality:With total lotus seed powder and milk powder ratio of 1:2 as the premise, using different proportions of ordinary lotus seed powder and germinative lotus seed powder(m:m=1:0,2:1,1:1,1:2,1:0), five different formulation compound yogurt was made and compared. The results showed that with the increasing amount of germinative lotus seed powder in the total lotus seed powder, the yogurt’s acidity increased and the color slants was more yellow. However, no obvious effect on its taste was found. Moreover, the content of protein, fat, lactose, hydrolytic amino acid content increased and the viable count slightly reduced. Compared with the fermented yogurt with pure milk powder, the average fat content and lactose content of five different formulation compound yogurt, respectively, was 3.31 g/100 g and 3.39 g/100 g. Relative to the control group,they were reduced by 8.05% and 14.60%. In addition, the average protein and hydrolysate amino acids content was 4.02 g/ 100 g and 3.448 g/100 g. Relative to the control group, they were increased by 14.20% and 22.96% respectively.The viable count on average was 8.10 ×108 CFU/g,1.77 times compared to the control.4. The application of HACCP system:Under HACCP principles and the hazard analysis, the 6 critical control points in the process of production of the lotus seed yogurt was determined. They were raw material selection, grinding powder slurry, mixing, sterilizing, bacteria preparation, vaccination, aseptic filling, sealing. According to those 6 points, HACCP monitoring system was developed, and the high quality protein lotus seed yogurt HACCP system was formed. |
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