Formation Regularities Of Volatile Substances In Wheat Flour Fermentation And Heating Processing

The basic raw material of pasta products is one of the main foods of wheat.It has various forms and types of products,and the flavor of pasta products is an important quality.The formation process depends on the composition of the flavor of wheat flour and the different processing methods.The main processing method of hot processing as food is the main process of flavor formation of pasta products.In this paper,wheat flour was used as the main raw material to explore the formation mechanism of volatile substances in the heating process.The research on each part is as follows.1.The formation of different volatile substances in wheat flour during semi-continuous heating was studied,and the formation temperature of each volatile substance was determined.In the process,a total of 92 volatile compounds were identified,including aldehydes(25),ketones(15),alcohols(9),nitrogen-containing sulfur compounds(6),benzene derivatives(15),furans.Class(10),acid ester(12).In the lower temperature range(60-100 °C),the flavor component of wheat flour is mainly composed of C6-C10 volatile aldehydes and alcohols.When the temperature exceeds 100 °C,the formation of a large amount of long-chain aldehydes and alcohols,furans,acids,esters,nitrogen-containing and sulfur-containing compounds constitutes an overall flavor profile,especially at 120 °C.At the same time,except for 1-pentanetriol,1-pentanol,1-heptanol,2-ethyl-1-hexanol,the amount of most volatile compounds is increasing throughout the heating process,especially from 90.°C rises to 130 °C.2.The formation of volatile substances during the semi-continuous heating of fermented wheat flour was studied.It was found that during the heating process,the alcoholic substance played an important role in the overall volatile matter profile,and the fermentation increased the formation temperature of some volatile substances related to the oxidation of oil,such as:-hexenal,trans,trans-2,4-heptadienal,trans-2-nonenal and 2,4-nonadienal,and the like.It also promotes the formation of heterocyclics,furans and benzenes.In addition,it was found that when the heating temperature was higher than 110 °C,the type of volatile substances began to increase,and when the temperature reached 120 °C,the composition and content of each volatile substance changed most significantly.3.Metabolomics analysis was used to analyze the metabolic profile of wheat flour during fermentation,and to explore the relationship between fermentation and volatile matter formation.It was found that the contribution of lipids to the overall volatile matter profile during fermentation was not prominent except for bioavailability.The metabolic utilization of amino acids and carbohydrates was the main cause of overall volatile matter formation.Meanwhile,the metabolism of yeast increases the content of free amino acid and monosaccharide in dough,but with the progress of fermentation,the content also begins to decrease,and is most obvious in 40-60 min,but the overall metabolism of small molecules is still at a high level.The results showed that the fermentation of yeast improved the nutritional composition of wheat flour.4.The composition and variation of basal metabolites and flavor metabolites during pasta baking were studied,and the relationship between basal metabolism and flavor formation was explored.The study found that the content of free amino acids and monosaccharides in the polar components in the pre-bake period increased slightly,and began to decrease after 15 min,while for the non-polar component lipids,it decreased significantly before 30 min,and then became slow.It indicates that the use of pre-lipids plays an important role in the formation of the overall flavor of the product during the baking process.In the later stage,the other forms of reaction such as Maillard reaction contribute the most to the formation of flavor.This provides guidance for the selection of baking time in the production process.