Study On Flavor Substances Of Chongqing Traditional Bacon And Its Safety

Chongqing traditional bacon is a famous smoke-dried meat product in southwest of China,and widely favored by consumers for its special and characteristic flavor.Chengkou traditional bacon is a representative of traditional Chongqing bacon,and its traditional processing was formed with many years' practice,adapting climate condition of Chengkou and the way of living by Chengkou's people.The aim of this research is to investigate the forming mechanism and pathways of flavor substances by studying the changes of main flavors and analyzing the flavor substances of Chengkou traditional bacon during processing.Contemporary,the safety of Chongqing traditional bacon is assessed by the content of B(α)P and nitrite remained in the bacon.The contents and results are as follows.1.Studies on the changes of flavor compounds in bacon during processingThe volatile flavor compounds extracted by SDE from bacon were analysed by GC/MS,with ethyl caprate as internal standard.In order to follow changes of volatile flavor compounds during processing,samples were taken after dry-cured,after roasted and smoked for 10 days,after roasted and smoked for 20 days,and after roasted and smoked for 30 days.The main results were:108 volatile flavor compounds were identified by GC/MS during four processing periods and the different compounds of each processing period were identified as follow:In the first period,41 flavor compounds were identified,including no kinds of hydroxybenzene,7 kinds of alcohol,3 kinds of aether,9 kinds of carbonyl,3 kinds of acid,10 kinds of ester,4 kinds of hydrocarbon and 5 kinds of others;In the second period,59 flavor compounds were identified,including 8 kinds of hydroxybertzene,6 kinds of alcohol,4 kinds of aether,9 kinds of carbonyl,4 kinds of acid,13 kinds of ester,11 kinds of hydrocarbon and 5 kinds of others;In the third period,68 flavor compounds were identified,including 12 kinds of hydroxybenzene,5 kinds of alcohol,3 kinds of aether,11 kinds of carbonyl,4 kinds of acid,15 kinds of ester,14 kinds of hydrocarbon and 4 kinds of others; In the forth period,72 flavor compounds were identified,including 13 kinds of hydroxybenzenes,5 kinds of alcohol,2 kinds of aether,13 kinds of carbonyl,4 kinds of acid,17 kinds of ester,15 kinds of hydrocarbon and 3 kinds of others;During the four processing periods,the comparable percentage of hydroxybenzene were 0.00%,25.54%,31.42%,33.19%respectively;the comparable percentage of alcohol were 21.94%,20.46%,16.25%,13.74%respectively;the comparable percentage of aether were 3.84%,3.77%,1.15%,0.88%respectively;the comparable percentage of carbonyl were 13.99%,11.97%,8.56%,8.88%respectively;the comparable percentage of acid were 1.26%,2.34%,2.37%,2.55% respectively;the comparable percentage of ester were 27.32%,24.98%,25.72%,24.96% respectively;the comparable percentage of hydrocarbon were 5.71%,7.86%,10.09%,12.69% respectively.The variety regulation of flavor compounds in bacon during processing was identified by the data above.The category,quantity and comparable percentage of hydroxybenzene and hydrocarbon increased obviously;the category and quantity of carbonyl and ester increased but the comparable percentage of them decreased;the category and quantity of alcohol and aether decreased;the category,quantity and comparable percentage of acid was not obviously increased.2.Studies on the forming mechanism of flavor substances during processingThe main active flavor substances were identified by analysis of the quantity of them,which were hydroxybenzene,carbonyl,alcohol,ester and hydrocarbon.Hydroxybenzenes were mainly the volatile compounds from the smoke,and the xylogen is the main reagent which creates hydroxybenzene in the bacon.In hydroxyl -benzene,the main effective flavor compounds were phenol-3-methyl,phenol,4-meth -yl -2-methoxy,phenol-2-methoxy, phenol-2,5-dimethyl,phenol- 4-ethyl-2- methoxy,2-methoxy-4-vinylphenol.Hydroxybenzene is the typical flavor compound in smoke food.Carbonyls were the production of fats' oxidation and Maillard reaction.In carbon -yl,the main effective flavor compounds for bacon were hexanal,benzaldehyde,2,4- decadienal.Alcohols may come from chemical degradation or microorganism action.The vol -atile compounds from the smoke were also responsible for the coming of alcohol in the flavor substance. In alcohol,the main effective flavor compounds for bacon were linalool,alpha-terpineol and 4-terpineol.Asters were related to complex chain-reaction.They may come from the esterifica -tion between alcohols and carboxylic acids which was produced by microorganism.In asters,the main effective flavor compounds for bacon were linalyl acetate,terpinyl acetate and nonanoic acid,ethyl ester.Hydrocarbons came from the fats' oxidation,but the main effective flavor hydro -carbons were due to the smoke.In hydrocarbons,the main effective flavor compound -ds for bacon were beta-myrcene,gamma-terpinene and limonene.3.Studies on the changes of sanitary index in bacon during processingBenzo(α)pyrene in bacon was detected after roasted and smoked for 10 days,20 days and 30 days, but not after dry-cured.The content of benzo(α)pyrene in bacon was increasing while the bacon was roasted and smoked.This shows that more smoke penetrated into the interior of the meat products, the more time it is exposed in the smoke environment in the process of smoke-cured.The content of benzo(α)pyrene in bacon final product was 4.6μg/kg.According to the Chinese food sanitary standard(GB7104-94),the content of benzo(α)pyrene in bacon is less than 5μg/kg,so the bacon we produced was eligible.In the sample after dry-cured,the content of nitrite was 5.11mg/kg.The content of nitrite was increasing which went with the time of sootiness and firing,and it was 7.23mg/kg in the final product.According to (GB2760-2007),nitrite remained in bacon is less than 30mg/kg,so the bacon we produced was eligible.4.Studies on the changes of physical and chemical index in bacon during processingIn order to understand more about the forming of bacon flavor,the physical and chemical index in bacon during processing was mensurated.In the first processing periods,the percentage of water was 47.21%,and the AV was 1.53mgKOH/g fat,and the PV was 0.0195g/100g fat;In the second processing periods,the percentage of water was 28.75%,and the AV was 2.68mgKOH/g fat,and the PV was 0.0269g/100g fat;In the third processing periods,the percentage of water was 21.58%,and the AV was 2.97mgKOH/g fat,and the PV was 0.0241g/100g fat;In the forth processing periods, the percentage of water was 18.33%,and the AV was 3.02mgKOH/g fat,and the PV was 0.0273g/100g fat.During processing,the rate of water decreasing in initial stages was higher than in the evening stages.The AV was increasing gradually and the PV was fluctuating.5.Studies on the changes of meat texture index in bacon during processingThe core of texture was hardness for meat.Hardness index reflected the changes of meat texture character.The more time the bacon was roasted and smoked,the harder it was.The main reason was that the content of water in the bacon was decreasing which made the meat massiness and better chewiness.This character could make the flavor of bacon stay longer time in nonnasality.6.Sensory estimation of bacon during processingFive standards of sensory estimation including color,hardness,dried level,taste of smoke food, taste of meat were used to estimate bacon during processing.Results show that the outcomes of sensory estimation were consistent with the changes of flavor compounds detected by GC/MS.So the content of flavor compounds which were detected in bacon can be used to evaluate the flavor of bacon.