| The goal of the experiment is to study the change of flavor substance about bacon in different storage condition.the main material of the experiment is GuoFu Rong traditional SiChuan bacon, the bacon was divided into three groups:A group(control group with vacuum packing);B group(adding tea polyphenol with vacuum packing); C group(adding sodium erythorbate with vacuum packing), then respectively were stored in the cold storage(5℃)and in the frozen storage(-18℃), the result are as follows:1 Bacon volatile aroma components changes during low temperature storage1.1 Bacon volatile aroma components changes during cold storageThere are 67 aroma composition in fresh bacon, storaged in 40d,80d,120d. A group check out the volatile aroma components respectively 57,56 and 75. B group check out the volatile aroma components respectively 38,69 and 64. C group check out the volatile aroma components respectively 52,68 and 63. Hydrocarbon compounds is the most content in aromatic,followed by ketone,aldehyde and phenolic compounds. There are also alcohol, ether, acid, and ester compounds.In cold storage, several characteristic flavor substances of bacon declined in cold storage, furan methanol and guaiacol show a significant downward trend in these substance. The volatile aroma number dose not change in a significant difference in the three groups(P>0.05). The result show that different antioxidant affect little about the change of volatile aroma competent.1.2 Bacon volatile aroma components changes during frozen storageDuring frozen storage, the total number of volatile aroma competent of sichuan bacon show a downward trend. There are 67 aroma composition in fresh bacon and decline to 40,57,57 respectively in each group until the end, the change of number of aroma compositions show a significant difference between the groups with anti-oxidants and the treatment group.In the frozen storage, the change of characteristic flavor shows a different trend, the flavor like guaiacol show a slowly downward trend, it descript that the longer keep, the lighter smell of bacon. The content of aldehydes were present a ladder down trend. The decrease of GHB'munber is associate with the increase of ester'number.2 The others flavor components change during low temperature storage2.1 The others flavor components change during cold storageThe water in fat bacon and lean bacon both decline in storage. The original content of water in A, B, C group is 14.51g/100g, then drop to 50.87g/100g,51.62g/100g,49.89g/100g respectively in each group during cold storage. The pH in at fat bacon and lean bacon both decline in storage, The original pH about fat bacon in group A, group B, group C is 5.94 and then decline to 5.62,5.72,5.66 in each group during cold storage, And the pH of lean bacon drop from 6.09 to 5.62,5.72,5.66 in the end. In the begin of the storage, the content of reducing sugar is decline, then arise at the last,the beginning content of reducing sugar(the fat bacon and lean bacon mixed together)is 0.386g/100g, then reduce to 0.426g/100g,0.451g/100g,0.455g/100g in A, B, C group during storage. The content of sodium chloride(the fat bacon and lean bacon mixed together), crude protein and amino acid (lean bacon only)all increase during the storage in every group. The beginning content of proteinin fresh bacon is 35.214% and reduce to 36.646%,36.136%,36.25% respectively in group A, group B and group C until the end. The content of amino acid drop from 0.466g/100ml in the beginning to 0.540g/100ml,0.628g/100ml,0.620g/100ml respectively in group A, group B and group C until the end. The change of this substance is the reason that arouse the flavor of bacon change during the storage.2.2 The others flavor components change during cold storageThe water in fat bacon and lean bacon both decline in frozen storage. The content of water about fat bacon drop from 14.51g/100g to 9.58g/100g,10.62g/100g and 9.87g/l00g respectively in group A, group B and group C until the end. The content of water about lean bacon decline from 54.97g/100g to 46.18g/100g,50.97g/100g,49.41g/100g in the end. The pH of bacon show a complicated change during the storage. In the fat part,pH value decreased at the first and then increased slightly, at the last show a downward trend. In the lean part, pH value decreased at the first and then increased in the end. the change trend of reducing sugar(the fat bacon and lean bacon mixed together) just as what it is in cold storage, the content of reducing sugar decrease from 0.386g/100g to 0.489 g/100g,0.450 g/100g,0.467 g/100g respectively in group A, group B and group C until the end. The content of sodium chloride(the fat bacon and lean bacon mixed together), crude protein and amino acid all increase during the storage in every group. The content of crude protein(lean bacon only) increased tardily, The beginning content of protein in fresh bacon is 35.214% and reduce to 38.237%,38.081%,38.061% in the end during frozen storage. The content of amino acid(lean bacon only) drop from 0.466g/100ml in the beginning to 0.658 g/100ml,0.636 g/100ml,0.666 g/100ml in the end. These flavor substance have an effect on the taste of bacon during the storage. 3 The texture and sensory changed in low temperature storage3.1 The texture and sensory changed in cold storageThe hardness and chewing of every group of bacon show a increasing trend, while, the springiness and cohesiveness of every group of bacon bacon show a decreasing trend in the same time during the cold storage. The result show that antioxidant can affect the change of meat texture and the effect should study further in the future. The score of sensory evaluation show that there is significant difference in each group in different storage condition. The bacon storage with antioxidant is better than the bacon without antioxidant and the bacon with tea polyphenol is better than the bacon with sodium erythorbate. The result is exactly like the consequence of texture analysis.3.2 The texture and sensory changed in frozen storageThe hardness and chewing of every group of bacon show a increasing trend, while, the springiness and cohesiveness of every group of bacon bacon show a decreasing trend in the same time during the frozen storage. The protection of bacon the texture change with tea polyphenol is better than the bacon with sodium erythorbate during frozen storage and there is no reference demonstrate the reason of this mechanism, so we should study further in the future. The score of sensory evaluation show that there is significant difference in each group in different storage condition. The bacon storage with antioxidant is better than the bacon without antioxidant and the bacon with tea polyphenol is better than the bacon with sodium erythorbate. The result is exactly like the of consequence of texture analysis.4 The mechanism of bacon flavor changes during low temperature storageThe POV value and AV value increase slowly during the low temperature storage because that the fat of bacon degrade. The speed of fat oxidized would get slower during the low temperature storage, but there will still generate sorts of short chain fat aldehydes and ketones, these aroma components are the most important part of bacon's flavor, which also lead to bacon smelly in the same time.
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