CCTV reporter found after from the fish market to buy one kilogram of shrimp and ice leaving only 7 gross weight of 1002 g samples thawed only 503 grams, a large part of the ice, thereby questioning whether to buy it is to buy shrimp or ice? Why use shrimp ice?
Shrimp and other seafood left the water is very likely to die, the body will lose its antimicrobial activity, these seafood organism itself moisture is high, generally about 80%. High moisture content of muscle tissue can easily be utilized by the microorganisms and deterioration caused by pollution, and produce unpleasant smell, but also lead to browning.
Specific to shrimp, shrimp itself contains enzymes and tyrosine, in the cold chain process can still remain active, if the temperature changes, exposure to oxygen, shrimp body oxidase (phenol or phenol oxidase enzyme) will tyramine acid oxidation, the production of melanin, it will lead head of the prawn, shrimp tail black, and even the whole shrimp are browning, but also a serious deterioration. Consumers should not want to buy discoloration, deterioration and even shrimp, right? Browning will directly influence consumers' purchase, for businesses, consumers do not buy is the biggest blow. Thus, in the post-harvest shrimp before sale, generally have a fresh color protection process. Common methods include controlling the temperature (frozen, refrigerated), cut off oxygen to lower the pH and so on. However, a single approach may have certain limitations.
Fresh shrimp technically there is a "frozen pack ice coating method of irrigation." Specific methods of operation are: frozen shrimp per plate, first in the bottom of the plate plus a small amount of ice water on the back cover, when the temperature dropped to -8 shrimp first add water, add water about two-thirds of the shrimp- when coupled with the basic frozen shrimp is good water, the amount of water at this time is usually not too much to just overshadowed lower when the shrimp body core temperature of -18 , can a library off the off the plate and then add a layer of glaze (ie pack ice coating). This frozen shrimp outer layer of ice which is also called "shrimp fresh ice." This fresh ice often added sodium metabisulfite, this preservation process means not only cut off the oxygen, but also reduce the PH, but also to ensure lower temperature, better able to prevent shrimp discoloration and deterioration.
Need to be reminded that this fresh shrimp processing mainly to meet the need for long-term storage or long-distance transport of places and people, does not mean that all the shrimp have this treatment, it does not mean that you can only buy such a shrimp. As a consumer, you can buy according to their needs fresh shrimp, provided you timely eat, or not eat, we also have to do a good job preservation measures. For occupying inland, away from the sea of people, it is almost only buy this kind of frozen shrimp, dried shrimp or buy it.
Consumers are questioning their own buy shrimp are a large part of the ice, it is often regarded in this sentiment spilled wholesalers who, in fact, enough to buy wholesale is this form of shrimp from food manufacturers, while food manufacturers aim is mainly to provide security.
This fresh ice use, there are some loopholes. On the microblogging do with a seafood expert @ Fan Xubing investment exchange, he reacted, currently the most serious shrimp ice pack there are two types: one is the South American shrimp farming, cooked and then ice packs, each pack ice can increase the weight of 15% -20% in recent years as more and more intense price war, more and more number of ice packs, ice packs can be four times the weight gain of 60% -100%. Due to the lack of control, some companies use a lot of fresh ice, there is no marked its actual content (which is most of the frozen shrimp in bulk, no food labels, if there is food packaging, should indicate the actual content on the label), there are some excessive ice pack phenomenon, the need to strengthen supervision.
References:
[1] Yu the silver, and other fresh shrimp Advances Technology of Food Industry, 2013, 34 (6): 396-400.
[2] Chen Feidong Shrimp fresh ice preparation technology and its application. 2007, Zhejiang Gongshang University master's degree thesis.
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