| Flour product is an Asian traditional staple food, and it contains rich nutrition facts such as protein, carbohydrates, lipids, minerals and vitamins which human body needs.Owing to simple production, good taste and flavor, fresh noodles are popular among consumers. However, fresh noodles are vulnerable to deterioration, not only the apparent changes in its form,especially the changes in the interior. First-class flour is used as raw materials to make fresh noodles in laboratory,and the factors affecting its shelf-life and qualities are studied. It is vital to solve the problems which constraints the industrialized development of fresh noodles, and is conducive to the industrialization process for staple food.Firstly, this paper studies the quality changes of fresh noodles during storage to provide the theoretical basis for its preservation technology research. The results showed that the noodles quality changes rapidly within 12 h, in addition, the turning point of fresh noodle quality was 24 h during storage. Noodles during storage had a series of quality deterioration, including the apparent deterioration of color, texture and cooking quality, and the internal changes of microbial content, moisture content, moisture distribution, protein molecular weight, accessible thiol(SHfree) content and starch viscosity. The statistical analysis indicated the changes of appearance had a significant correlation with internal changes in fresh noodles. Further, the molds resulting in fresh noodles mildew were isolated, purified and identified: the main factors are Mucor and Aspergillus species. A total of 8 kinds of molds were isolated, including 2 species of Aspergillus genus, 1 species of the genus Penicillium, 3 species of Mucor; 1 species of the Rhizopus, 1 species are unknown.Secondly, the water-adding amount, mixing time and the fermentation time parameters in fresh noodle making process were optimized to obtain the fresh noodles with relatively low water activity, and this would extend the shelf-life of fresh noodles. The technical parameters were designed to be 40% water-adding amount (based on flour weight), 4 min of mixing time at a slow speed (52 r/min), 3 min mixing time at rapid speed (73 r/min), 20 min of fermentation. The water activity of fresh noodles produced under this condition was 0.955. And the water activity decreased with the decrease of water-adding amount.However, when the amount of adding water was less than 40%, the flour was difficult to form a dough.And then, the fresh noodles were treated with moderate dehydration at RH (relative humidity) of 60%, dehydration temperature of 40?. the moisture content of fresh noodles was decreased to 23.5% after dehydration for 30 min. These treatments can reduce the water content of fresh noodles, and help the water molecules combine with other components. Moreover, the original properties of fresh noodles such as, texture, color and microstructure could be remained. And the dehydration process could also help solve the problem of adhesion for fresh noodles. After moderate dehydration treatment, the shelf-life of fresh noodles was prolonged from 24 h to 48 h or more, making it easier to store.Finally,both the effects of packaging styles on the preservation of fresh noodles and preservation experiments were investigated. The results showed that CO2 had a significant inhibitory effect on microbial (p<0.05), but the best packaging method is to use vacuum packing equipped with deoxidizer. At room temperature, the total number of colonies remained relatively low after storage for 72 h in this way. The preservation experiments indicated that,the shelf-life of fresh noodles was to be about 6 days under the storage temperature of 37?; 10 days under the storage temperature of 25?; more than 12 days under the temperature of 4?. In general, it showed that the fresh noodles after moderate dehydration, deoxidizer and vacuum packing had a greatly extend shelf-life. |
PDF Full Text Request