Study On Change Of Quality And Mechanism Of Fresh Meat Zongzi In The Shelf-Life

Traditional food is a Chinese national food which has a unique flavor and characteristics, and well received by the consumers. At present, the key problems of the development of traditional rice products industry are production expansion, the extension of shelf life and to maintain product quality in the shelf-life. Therefore, how to effectively control the quality problem of traditional food and how to maintain product freshness, are the key issues need to be resolved, and also an important technical problem plagued producers, and at the same time the rice products lead to the safety issues are most concerned by consumers.Changes in microbial, changes in texture characteristics, and the changes in volatile flavor substances in the shelf life of Zongzi were studied in the paper. The overall change of quality of Zongzi in the shelf-life was analyzed by electronic nose. The main results are summarized as follows: 1. Changes in microbial of fresh meat Zongzi in the shelf lifeFresh meat Zongzi were stored at 25℃, and couldn't detect microorganisms in 48 h, and the plate counts exceeded the national standard after 144 h; at 37℃, plate counts exceeded the national standard after 48 h. Microbiological changes in Zongzi were studied at 25℃. During the first 2 days, there were no microorganisms in Zongzi. The plate counts were raised after 3 days, and Staphylococcus was dominant; the Bacillus was dominant after 5 days of storage; the count of mould increased slowly. But the mould were dominant at 37℃storage conditions. The dominant microorganisms were identified:the species were Bacillus subtil is, Bacillus pumilus, S. epidermidis.The antimicrobial activity of bamboo leaf extracts was studied, and the results show that:the bamboo leaf extracts has inhibit in bacteria, and the best inhibitory effect is on Staphylococcus aureus, and then are on Bacillus subtilis, E. coli, Salmonella. Bui it has no inhibitory effect on the mold.2. Changes in texture characteristics of fresh meat Zongzi in the shelf lifeThe changes in texture characteristics and moisture content at 25℃were studied, the results show that:the hardness, gumminess and chewiness of Zongzi were increased with the storage time increased, but there were little change in cohesiveness and adhesiveness. Through the correlation analysis, show that:there were a negative correlation between hardness and gumminess, and a positive correlation between hardness and springiness, and a significant correlation between hardness and chewiness. There was a significant correlation between gumminess and chewiness, springiness. There was a significant correlation between springiness and cohesiveness, chewiness. And adhesiveness is generally not associated with other parameters.The moisture content of Zongzi was decreased with the storage time increased, through the correlation analysis between moisture content and texture parameters, show that:there were a negative correlation between moisture content and hardness, gumminess, cohesiveness, chewiness.Changes in distribution of water in Zongzi in shelf life were studied by LF-NMR, found that:there were two different T2 section in Zongzi which respectively represented T21(bound water),T22(structural water). T21 and its proton density had a small change. And T22 and its proton density was decrease with the time increased. It showed that the major factor on quality of Zongzi in the shelf life was the changes of structural water.3. Changes in volatile flavor substances of fresh meat Zongzi in the shelf lifeChanges in volatile flavor substances of Zongzi in the shelf life were analyzed by GC-MS, the results show that:The main material types are aldehydes, esters, acids, alkanes, alcohols, aromatic and alcohol. The main volatile substances are:Dodecane, Tetradecane, Hexadecanal, Octadecanal, Oleic Acid, n-Hexadecanoic acid, Hexadecanoic acid, ethyl ester, Ethyl Acetate, Naphthalene,2,6-dimethyl-, et al. Change in types of volatile material were:aldehydes, alkanes, and esters were decreased with storage time increased, and acids were increased. Aromatic compounds have no changes during storage.4. Comprehensive Evaluation of Freshness in the shelf life of fresh meat Zongzi by electronic noseEstablish of the relevance of overall quality in the shelf life of Zongzi by electronic nose technology, and the results show that: electronic nose can well distinguish the overall quality of Zongzi. There was a good correlation between Zongzi shelves time and scores of linear discrimination. Further more establish quality model and shelf time model, and the models can better predict the quality and shelf time of Zongzi.