Study On Process Optimization Of Rose Jam And Influence Of Storage Conditions On Its Quality

Xinjiang is rich in rose resources,rose jam is a kind of traditional food of Uygur people in Xinjiang.It has rich nutritional value and medicinal value.However,the traditional processing technology is backward,and the sanitary quality of the products is poor.In this study,the ‘Damascus' roses in Hotan Xinjiang was used as raw material,the processing parameters of rose jam and raw materials ratio was optimized,the nutrient compositions were analyzed,meanwhile the effect of storage conditions on the quality of rose jam was studied.The results are as follows:(1)Selection of varieties raw material for rose jam.The nutrient compositions and aroma components of‘Damascus' rose and ‘Zizhi' rose were comparative analyzed.The results showed that the contents of vitamin C,crude fiber and crude fat of the two varieties had no significant differences,but the content of reducing sugar had significant differences,the content of reducing sugar in ‘Zizhi' rose was 38.14% higher than that in ‘Damascus' rose.The contents of calcium and zinc in ‘Zizhi' rose were 26.79% and 41.18%higher than that in ‘Damascus' rose,their differences were significant,but other mineral elements had no significant differences between the two varieties.Among the 18 kinds of amino acids detected,there were7 kinds of essential amino acids,the total amino acid content in ‘Zizhi' was 27.85% higher than that in‘Damascus' rose.The contents of polysaccharides,polyphenols and flavonoids in the active components of‘Damascus' rose were 31.74%,41.23% and 25.13% higher than those of ‘Zizhi' rose,respectively.The anthocyanin content in ‘Zizhi' rose was 61.26% higher than that in ‘Damascus' rose.The aroma compounds detected in ‘Damascus' and ‘Zizhi' rose were 32 and 41,respectively,and the differences were significant.The aroma compounds detected in ‘Damascus' and ‘Zizhi' rose were 32 and 41,respectively,and the differences were significant.‘Damascus' rose has high content of alcohols,and its aroma is prominent,compared with the Bulgarian ‘Damascus' rose,their main aroma components were similar.The jam comparison showed that,‘Damascus' rose jam had higher sensory score than ‘Zizhi' rose jam.‘Damascus' rose jam had dull astringency,full rose aroma,bright color and appearance,as well as better quality than ‘Zizhi' rose jam.Therefore,this paper selected ‘Damascus' rose as the raw material of rose jam.(2)Optimization of rose jam.The effects of different sweeteners and their additives,color fixative and additive on the quality of rose jam were studied in ‘Damascus' rose.Research showed that the more suitable sweetener were white sugar and high fructose syrup.The optimum ratio of rose,sugar and high fructose syrup was 1:2.5:0.5.Single factor experiments were conducted to compare the effects of citric acid,malic acid,ascorbic acid,sodium chloride and L cysteine on color fixative of rose jam.Response surface optimization experiment were carried,determined the best formula were 0.16% citric acid,0.16%malic acid and 0.31%sodium chloride.(3)Quality analysis of rose jam.The sensory indexes,nutrient components,aroma components and antioxidant qualities of traditional technology and new technology of rose jam were comparative analyzed.The results showed that rose jam made of new technology had higher sensory score than that of traditional craft.The new technology made rose jam had the advantages of bright color,uniform texture,no sand returning,strong antioxidant ability,and the content of heavy metals was lower than that made in traditional technology.The results implied that the new technology can obviously improve the quality of rose jam.(4)Effects of storage conditions on the quality of rose jam.The effects of light and temperature on the quality of rose jam were studied.The rose jam was stored at normal temperature with exposure to light,normal temperature with avoiding light and 4 degrees refrigerated storage,interval of 30 d measure its browning degree and the active components and observe the quality change.The results showed that with the extension of storage time,the browning degree of rose jam increased,and the color gradually became darkened.After 120 d storage,the browning speed accelerated quickly,the sensory quality and active components also decreased with extension of storage time.At the 4 degrees cold storage,the color and the active components of rose jam were higher than that in normal temperature storage,but the rose jam appeared sugar crystallization,and the microstructure was uneven after storage at 4? for 120 d.