Study On Quality Change And Safety Of Xiangxi Traditional Bacon In Low Temperature

Xiangxi traditional bacon is an outstanding representative of Hunan bacon, and it has a very high development value. At present, production and distribution of Xiangxi bacon are generally in a backward state which process seasonally and booming sale. The way for storage is hanging in the ventilation. But this way has many limitations, such as short storage time, and easy to spoilage etc. Research and discussion on quality change and safety of Xiangxi bacon in low temperature during storage not only could enrich the theory value, but also are the objective requirement of improving product quality.The main material of the experiment is Xiangxi traditional bacon. Researching on quality change and safety of Xiangxi bacon by selecting three factors that the way of packing (bulk or vacuum-packed), temperature (room temperature,5℃ or -18℃) and the addition of antioxidant (whether adding 0.2g/Kg ascorbic acid or not). The goal of the experiment is to get the quality indexes and edible safety index fluctuation, and to reveal the mechanism of the corruption, which can provide basic data to solve practical problems. Specific contents and results are as follows:1. Change rules of qualityDuring storage, the change of bacon sensory score, fat content, protein content, and pH value overall show a downward trend, but free fatty acid content, free amino acid, Nacl content are on the increase. Compared with the room temperature storage, the low temperature storage is more conducive to maintain the stability of the quality of bacon.(1)Sensory estimation result:In bulk without antioxidant acid at room temperature, the shelf life of bacon is in 90 days. In vacuum-packed without antioxidant acid at room temperature, the shelf life of bacon is in 150 days. The shelf life of bacon at room temperature, in vacuum-packed and added ascorbic acid is in 180 days. The shelf life of bacon at 5℃ in vacuum-packed without antioxidant acid is in 210 days. The shelf life of bacon at 5℃ in vacuum-packed and added ascorbic acid is in 240 days.(2)Fat content and free fatty acid content:During the period of storage in 0-90 days, fat content at 5℃ is more stable than it at -18℃. In other words,5℃ is more conducive to Bacon’s short-term (0-90 days) storage.(3)Protein content and free amino acid content:In all the treatments, its protein decomposition is the most serious that the bacon is in bulk without antioxidant acid at room temperature. In order to keep the quality of bacon, bacon should not be saved in bulk without antioxidant acid and at room temperature for a long time. Packaging is one of the influence factors of free amino acid.(4)Nacl content:According to the law GB2730-2005, the Nacl content of bacon is restricted to be more than 7%. So the shelf life of bacon at the room temperature and in bulk during storage must be short than 90 days.(5) pH value:The storage temperature has remarkable influence on pH value. And the lower the temperature is, the slower the pH value changes.2. Eating safetyDuring storage, AV value, POV value, TBA value, TVB-N value, and nitrite content are overall on the increase. Colony total number generally remains at 106cfu/g.(1)Related indexes about fat Degradation:According to the law GB2730-2005, AV value of bacon is restricted to be more than 4.0%. For this reason, the shelf life of bacon at the room temperature and in bulk during storage must be short than 45 days. The shelf life of bacon at the room temperature, and in vacuum-packed during storage must be short than 120 days. The shelf life of bacon at the room temperature, in vacuum-packed and added ascorbic acid must be short than 150 days. The shelf life of bacon at the cold temperature, and in vacuum-packed during storage must be short than 180 days. According to the same law, POV value of bacon is restricted to be more than 0.50g/100g. For this reason, the shelf life of bacon at the room temperature and in bulk during storage must be short than 75 days. Thus, the correlation between AV value and POV value is insignificant.(2)TVB-N value:The TVB-N values of bacon in all of cases are greater than primes standard (<20mg/100g) of the law SB/T 10294-2012, but conform with the secondary standard (<45mg/100g).(3)Nitrite content:Adding ascorbic acid not only conducive to the preservation of food quality, but also prevent the formation of carcinogens.(4) Total number of colony:The effects of adding ascorbic acid on the total number of colony is not significant.(5)The number of Coliform:The numbers of Coliform of bacon in all of cases conform to the law GB2726-2005.(6)Pathogenic bacteria:In all of cases, Xiangxi bacon is not detected Salmonella, Staphylococcus aureus, Shigella, and Listeria monocytogene.