Study On The Aromas Formation Of Castanea Henryi During Roasting And Its Application In The Process Of Castanea Henryi Puree

Castanea henryi(C.henryi)is a nutritions food material with good flavor and high consumer acceptance.However,C.henryi is usually sold fresh due to its short harvest period and shelf life.In addition,serious loss of flavor and big change of color happened during its processing and storage.So,the product form of C.henryi was simple,which failed to meet the requirements of consumers and restrains the development of C.Henryi industry.The purpose of this research is to study the material basis and reaction conditions for the formation of aromas,and analyze the rule of aromas variation during roasting,thus providing the theoretic basis and technological support for flavor retain during the processing of C.henryi.C.henryi from Qingyuan,Lishui was used as raw material.The nutrition constituent and the products from Maillard reaction in roasting of C.henryi with different conditions were measured.The rule of aroma variation during roasting was analyzed,the characteristic flavor components were determined.A new product of C.henryi puree was developed.Specific research results were as follows:(1)Starch content of C.henryi decreased not significantly(P>0.05)during roasting in three different conditions(150℃,200℃ and 230℃)while the content of soluble protein reduced significantly(P<0.05).Reducing sugar and maltose reached the peak point and then decreased,respectively.While fructose,glucose and sucrose decreased significantly(P<0.05).Fructose decreased 51.22%,40.24%,48.78%and glucose decreased 58.18%,50.91%and 58.18%,respectively.And the amount of reduction of glucose was greater than fructose,which indicated that glucose was the main substance participated in Maillard reaction,and then fructose.The total free amino acids in fresh C.henryi were 31.44mg/g(dry base);most of them were aspartic acid,glutamic acid,asparagine and arginine,the other amino acids content was less.After roasting,the total free amino acids in C.henryi decreased significantly(P<0.05),and aspartic acid,glutamic acid,asparagine,glutamine,arginine,tyrosine and lysine decreased significantly(P<0.05).The change of amino acid profiles showed aspartic acid,glutamic acid,asparagine and arginine were the main amino acids in Maillard reaction during roasting process of C.henryi.(2)The pH of fresh C.henryi was 6.27,and the pH value decreased significantly(P<0.05)after roasting,and the higher temperature led to the greater declined.The AE*value of C.henryi increased significantly(P<0.05)as temperature and time increased.The UV absorbance at 294 nm were enhanced with time in three temperature(P<0.05).And the value was linearly correlated with time,the correlation coefficients were 0.8220,0.9062 and 0.6837(P<0.05).The variation of pH,total chromatic aberration and the intensity of UV absorbance indirectly suggested that the degree of Maillard reaction enhanced with temperature and time.5-Hydroxymethyl furfural(5-HMF)in C.henryi increased at first and then decreased,and reached the maximum value at 20 min in 150℃and 15 min in 200℃ and 230℃ respectively.The fluorescence intensity changed and reached the peak point at 20 min in 150℃ and 200℃ and 15min in 200℃,and the trend was similar to 5-HMFwhich.The variation of 5-HMF and the fluorescence intensity showed that it would enter into another stage of Maillard reaction when roasted in 150℃ and 200℃ for 20 min and while in 230℃ for 15 min.(3)The overall aroma of C.henryi was measured by electronic nose and analyzed with the methods of PCA analysis and LDA analysis.The results showed that the great changes of flavor occurred at 15 min in 150℃,15 min in 200℃,and 10 min in 230℃ respectively,which were the inflection points of flavor during roasting.During the remaining time after inflection point,the flavor presented no apparent change(P<0.05).Therefore,inflection points of flavor confirmed by electronic nose could guide the roasting conditions of C.henryi,and improved the degree of homogeneity of quality.(4)The volatile components of roasted C.henryi were determined and analyzed by gas chromatography-mass spectrography(GC-MS).The results showed that 72 kinds of volatile components determined by GC-MS were mainly ketones,acids,and esters.Volatile hydrocarbons,acids,alcohols and esters decreased,while ketones and heterocyclics increased.Aldehydes reached its valley value and then increased,and aromatics were just the opposite.Furanones were main components and 4-Hydroxy-2,5-dimethyl-3(2H)furanone,2,3-Dihydro-3,5-dihydroxy-6-m ethyl-4H-pyran-4-one and Maltol were the characteristic compounds of roasted C.henryi.(5)The new product of C.henryi puree had been developed by adopting the baking-and-frying technology with the addition of high fructose corn syrup(HFCS)to increase the content of products from Maillard reaction and enhance the flavor of C.henryi puree.With the indicator of sensory evaluation and the orthogonal test,the optimized technological condition was determined:the roasting temperature was 200℃,roasting time was 15 min,the volumes of added buttery and HFCS were 8%and 12%,respectively.