烘烤条件对核桃发酵乳流变特性及风味的影响

Effects of roasting conditions on rheological properties and flavor of walnut fermented milk

烘烤是食品加工中提升风味的重要手段,为了探究核桃经不同温度烘烤后其发酵乳凝胶强度和风味的变化,该文以未烘烤、60、90、120、150℃烘烤15 min的核桃为原料制作核桃发酵乳,并考察其流变特性、质构特性和色度的差异;同时定量和定性分析了不同发酵乳挥发性风味物质的组成及含量。结果表明,核桃在90℃、烘烤15 min后制作的发酵乳具有最强的凝胶结构,其表观黏度、储能模量和损耗模量均显著大于其他各组(P<0.05)。在不同烘烤处理的核桃发酵乳中共鉴定出了81种挥发性风味化合物,且香气活性值≥1的挥发性风味物质共有16种。主成分分析的结果表明,不同烘烤条件下核桃发酵乳的挥发性风味物质存在差异,当烘烤温度高于90℃时,醛类、酮类、醇类、呋喃类和吡嗪类物质的增加将有助于核桃发酵乳风味的提升。该研究将为核桃发酵乳制作过程中烘烤条件的确定提供指导。

Roasting is an essential way to enhance flavor in food processing,herein,the effects of roasting on the gel strength and flavor of walnut fermented milk were studied.Walnut fermented milk was prepared from non-roasted walnuts or roasted walnuts at 60,90,120 or 150℃for 15 min.The changes in rheology,texture,and color of fermented milk were investigated.At the same time,the composition and content of volatile flavor compounds were analyzed quantitatively and qualitatively by headspace solid-phase microextraction gas chromatography-mass spectrometry(HS-SPME-GC-MS).The results showed that the fermented milk produced by roasted walnut at 90℃for 15 min had the strongest gel structure.Its apparent viscosity,storage modulus,and loss modulus were significantly higher than those of other groups(P<0.05).Eighty-one volatile flavor compounds were identified in walnut fermented milk with different roasting conditions,including sixteen volatile flavor compounds with aroma activity value≥1.The results of the principal component analysis showed that the volatile flavor compounds of walnut fermented milk were different from each other.When the roasting temperature was higher than 90℃,the increase of aldehydes,ketones,alcohols,furans and pyrazines was helpful to improve the flavor.This study will provide a guidance for the determination of roasting conditions in the production of walnut fermented milk.