【作者】 王峥；

【导师】 张国权；

【作者基本信息】 西北农林科技大学 ， 食品科学与工程， 2023， 硕士

【摘要】 全谷物是健康和可持续饮食的重要支柱。青稞作为全谷物的良好来源,具有很高的营养价值和食疗功效。糌粑俗称青稞炒面,是青稞全籽粒经过炒制、磨粉等工艺制成的全谷物粉状食品。目前,糌粑已实现工业化生产,但在加工与贮藏过程中仍存在质量不稳定、脂质易氧化酸败的问题,这严重限制了糌粑的工业化发展水平。虽然已有相关研究工作集中在糌粑加工工艺及产品质量控制方面,但关于青稞加工前后品质及风味物质变化的研究较少,对于青稞糌粑粉在贮藏过程中的氧化变化也鲜有报道。本研究对炒制前后青稞粉原料与糌粑粉产品的品质进行检测,分析了糌粑粉在贮藏期间脂质氧化的变化规律,并测定不同包装条件下的糌粑粉在加速贮藏期间氧化指标、抗氧化活性、品质及挥发性风味物质的变化,以期为青稞糌粑粉的合理加工及贮藏提供科学的理论与技术依据。主要研究结果如下:(1)在不同的炒制条件下糌粑粉品质会有所变化,采用综合加权评分法优化得到糌粑粉的最佳炒制工艺条件:炒制功率1600 W,炒制时间4 min,水分含量20%。其中炒制时间是影响糌粑粉综合评分的关键。经高温炒制后,糌粑粉的营养成分(脂肪、总淀粉、粗纤维、抗氧化物质)损失。青稞经过炒制后可以达到灭酶的效果,脂肪酶和脂肪氧化酶活性分别下降40.75%和34.09%,脂肪酸值和过氧化值分别下降45.14%和30.37%,丙二醛值由炒制前的0.42 mg/kg增加至0.48 mg/kg。(2)在贮藏过程中,青稞全粉和糌粑粉的脂肪含量整体呈下降趋势,脂肪酸值、过氧化值、脂肪酶活性呈先上升后下降的趋势,丙二醛值、脂肪氧化酶的活性呈先上升后下降之后又上升的趋势。加速贮藏条件下的糌粑粉在第15 d(相当于常温贮藏120d)时品质已发生氧化劣变,此时糌粑粉的过氧化值为5.57 mmol/kg,丙二醛值为1.38mg/kg,可将其作为判断糌粑粉品质劣变的临界指标。与青稞粉相比,经高温炒制后,糌粑粉的香气种类更加丰富,醛类、酸类和杂环类物质含量增加,酮类和烃类含量减少。哈败后的糌粑粉风味物质种类明显减少,酯类、烃类和酸类含量增加,杂环类含量减少。此外,己醛的浓度可被认为是糌粑粉氧化哈败的预警指标,当其含量超过50%时,糌粑粉开始出现哈败味。(3)随着贮藏时间的延长,不同包装条件下糌粑粉的水分含量呈显著下降的趋势,脂肪酸值呈显著增加的趋势,过氧化值、丙二醛值呈先上升后下降的趋势。4种普通包装的糌粑粉在加速贮藏15 d(相当于常温贮藏120 d)时均发生氧化劣变;4种铝箔包装的糌粑粉在加速贮藏30 d(相当于常温贮藏240 d)时出现氧化劣变;脱氧剂和抗氧化物质可有效延缓糌粑粉脂质氧化的速度,减轻其品质劣变的程度。糌粑粉的抗氧化活性随贮藏时间的延长而逐渐降低。色差值ΔE及白度指数WI在其品质劣变后均有所上升;吸水指数和膨胀度随贮藏时间的延长而增加,溶解度则呈先下降后上升之后又下降的趋势;在糌粑粉品质劣变后,糌粑团的硬度和咀嚼性增加,弹性和内聚性略有下降。电子鼻的W1W和W5S传感器能够区分糌粑粉炒制及贮藏过程中气味的变化;糌粑粉在贮藏过程中风味物质种类及含量呈先下降后上升的趋势,糌粑粉贮藏期间的风味品质劣变可能是由醛类、酸类等挥发性成分的积累导致的。更多还原

【Abstract】 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.更多还原