Study On Roasting Technology And Storage Stability Of Highland Barley Zanba Powder

Whole grains are an essential pillar of a healthy and sustainable diet.As a good source of whole grains,highland barley has high nutritional value and therapeutic effects.Zanba,commonly known as highland barley fried noodles,is a whole grain powder food made from the whole grain of highland barley through stir-frying,grinding and other processes.Currently,zanba has achieved industrial production,but there are still some problems in the processing and storage process,such as unstable quality,easy oxidation and rancidity of lipids,which seriously limits the development level of zanba industrialization.Although some related researches focus on the processing technology and product quality control of zanba,there are few studies on the quality and flavor changes of barley before and after processing,and few reports on the oxidation changes of barley zanba powder during storage.This study detected the quality of barley powder and zanba powder before and after roasting,analyzed the changes in lipid oxidation of zanba powder during storage,and measured the changes of oxidation index,antioxidant activity,quality and volatile flavor of zanba powder under different packaging conditions during accelerated storage,in order to provide scientific theoretical and technical basis for the reasonable processing and storage of highland barley zanba powder.The main research results are as follows:(1)The quality of zanba powder changed under different roasting conditions.The optimal roasting conditions of zanba powder were obtained by using the comprehensive weighted scoring method: 1600 W of roasting power,4 min of roasting time,and 20% of moisture content.The roasting time is the critical factor affecting the synthetical score of zanba powder.After roasting at high temperature,the nutritional components(fat,total starch,crude fiber,antioxidant substances)of zanba powder were lost.Highland barley can achieve the effect of enzyme inactivation after roasting,the activity of lipase and lipoxygenase decreased by 40.75% and 34.09%,respectively.The fatty acid value and peroxide value decreased by 45.14% and 30.37%,respectively.The malondialdehyde value increased from 0.42 mg/kg to 0.48 mg/kg.(2)During storage,the fat content of barley powder and zanba powder showed a downward trend,the fatty acid value,peroxide value and lipase activity showed a trend of first rising and then falling,the malondialdehyde value and the activity of lipoxygenase showed a trend of first rising and then falling and then rising.The quality of zanba powder under accelerated storage condition has oxidized and deteriorated on the 15 th day(equivalent to 120 days of normal temperature storage).At this time,the peroxide value of zanba powder is 5.57 mmol/kg,and the malondialdehyde value is 1.38 mg/kg,which can be used as the critical index to judge the quality deterioration of zanba powder.Compared with barley powder,after high-temperature roasting,zanba powder has richer aroma types,more aldehydes,acids and heterocyclic substances,and less ketones and hydrocarbons.After zanba powder is spoiled,the content of esters,hydrocarbons and acids increased,and the content of heterocyclic compounds decreased.In addition,the concentration of hexanal can be considered as an early warning indicator of zanba powder’s oxidation and rancidity.When its content exceeds 50%,zanba powder begins to show rancidity.(3)With the extension of storage time,the moisture content of zanba powder in different packing conditions decreased significantly,the fatty acid value increased significantly,the peroxide value and malondialdehyde value increased first and then decreased.Four kinds of zanba powder in ordinary packaging were oxidized and deteriorated after 15 days of accelerated storage(equivalent to 120 days of normal temperature storage).Four kinds of zanba powder packed with aluminum foil showed oxidative deterioration after accelerated storage for 30 days(equivalent to 240 days at room temperature).Deoxidizer and antioxidant substance can effectively delay the speed of lipid oxidation of zanba powder and reduce the degree of quality deterioration.The antioxidant activity of zanba powder decreased gradually with the extension of storage time.The value of chromatism ΔE and whiteness index WI increased after the quality of zanba powder deteriorated.The water absorption index and swelling increased with the storage time,while the solubility decreased first,then increased and then decreased.After the quality of zanba powder deteriorated,the hardness and chewiness of zanba dough increased,while the springiness and cohesiveness decreased slightly.The W1 W and W5 S sensors of the electronic nose can distinguish the changes of odor during the roasting and storage of zanba powder.During the storage of zanba powder,the type and content of flavor compounds decreased first and then increased.The deterioration of flavor quality of zanba powder during storage may be caused by the accumulation of volatile components such as aldehydes and acids.