| Yunnan walnut has a long history of cultivation and is widely distributed in planting areas.Walnut kernel is the most useful part of walnut plant,its nutrition is rich.At present,the research and utilization of walnut kernel products are relatively few,which is not conducive to the development of walnut industry.With Yunnan Yangbi walnut kernel as raw material and tangerine peel as main raw material,the Yangbi product is marinated.Through the uniform design optimization of tangerine peel marinated walnut technology,the main auxiliary materials tangerine peel and walnut volatile flavor substances before and after processing were measured,to explore the effect of processing technology on tangerine peel walnut kernel flavor quality.Through the study of different antioxidants on the oxidation stability and shelf-life of walnut kernel prediction,walnut kernel product development to provide a theoretical basis.The contents and results of this study are as follows:(1)Based on sensory scores and texture characteristics as indexes,the optimal technological parameters of marinating walnut with tangerine peel were as follows:marinating time 15 min,soaking temperature 60℃,salt content 0.048%,tangerine peel content 0.08%,drying time 26 min,drying temperature 40℃.The quality and physical and chemical properties of dried tangerine peel and walnut kernel after baking were investigated.It was found that the moisture content of dried tangerine peel and walnut kernel before and after baking was significantly decreased(P<0.05),and the moisture content was 10.36±1.49% before baking and 0.31±0.77% after baking.Crude protein content decreased from 12.89% to 9.31%;Crude fat content increased to 67.45%;The contents of total flavonoids and total polyphenols had no significant effect,while the total sugar content decreased to 3.67% after baking.After baking,the walnut kernel showed a yellowish color,and the brightness value(L*)of roasted walnut kernel was significantly higher than that of raw walnut kernel(P<0.05).The color quality of roasted walnut kernel was slightly better,and the hardness,crispness and chewability of dried tangerine peel walnut kernel increased after baking.(2)Based on sensory scores and texture characteristics,the optimum parameters of marinating walnut were as follows: marinating time 15 min,soaking temperature 60℃,salt addition 0.048%,orange peel addition 0.08%,drying time 26 min,drying temperature40℃.The quality and physicochemical properties of walnut peel after baking were investigated.The moisture content of walnut peel before and after baking was significantly decreased(P<0.05),which was 10.36±1.49% before baking and 0.31±0.77% after baking.The crude protein content decreased from 12.89% to 9.31%.The crude fat content was significantly increased,which was 57.05±0.48% before baking and 67.45±1.27% after baking.The contents of total flavonoids and total polyphenols had no significant effect,while the content of total sugar was reduced to 7.15±0.21% before baking and 3.67±0.31%after baking.The color of roasted walnut was yellowish,and the brightness value(L*)of roasted walnut was significantly higher than that of raw walnut(P<0.05).The color and quality of roasted walnut were good,and the hardness,crispness and chewability of roasted orange peel walnut were increased.(3)A total of 90 volatile components(including monomers and dimers)were identifie d during the processing of tangerine peel,including 21 aldehydes,12 alcohols,9 ketones,9lipids,14 olefins,4 acids,1 other class,and 20 undefined compounds.A total of 89 volatil e flavor compounds were identified during the processing of tangerine peel and walnut ker nel,including 15 ketones,12 alcohols,6 olefins,5 lipids,2 acids,1 pyrazine and 29 undefi ned compounds.On the basis of PLS-DA and VIP>1,P<0.05,a total of 31 signature volatil e compounds(including monomers and dimers)of walnut meat from tangerine peel were s creened.They are: 3-Methyl butanal,E-2-Hexenal,Hexanal,Ethyl acetate,E-2-hexenol-M,alpha-Thujene,Ethyl formate,2-3-Pentanedione,Butan-2-one,alpha-Terpinene,Limonen e,Hexanal,Ethyl propanoate,Ethyl butanoate,alpha-Fenchene,alpha-fenchene,E-beta-oci mene,beta-pinene,Linalool,1-Hydroxypropan-2-one,3-Hydroxybutan-2-one,1-Propanol,Octanal,beta-ocimene,Methyl hexanoate,Sabinene,alpha-Thujene and Camphene,Ther efore,these aroma components can be used as volatile differentiating compounds in the ste wed walnut with orange peel.Among them,terpenes,which are the characteristic aroma co mponents of orange peel,mostly have the aroma of lemon,herbs and dry wood.(4)Among the 31 compounds in VIP>1,P<0.05,the characteristic volatile component s shared by the main excipients tangerine peel and tangerine peel walnut kernel were as fol lows: Ethyl acetate,Butan-2-one,Limonene,Ethyl format,1-Hydroxypropan-2-one,Camp hene decreased peak area and its relative content in tangerine peel and walnut kernel roasti ng process,but increased in tangerine peel and walnut kernel roasting stage.Other substan ces except Ethyl formate showed a decreased trend in walnut kernel haling process.These r esults suggest that the flavoring substances in tangerine peel may migrate from tangerine p eel to walnut kernel during the process of marinating and roasting,thus achieving the effect of flavoring. |
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