NaCl添加量及pH对马铃薯泥品质特性的影响

该试验以蒸制熟化的马铃薯泥为对象,利用电子眼、应变控制流变仪、物性测试仪、扫描电子显微镜、激光共聚焦显微镜、X-射线衍射仪、核磁共振分析系统等,研究NaCl添加量（0%、0.5%、1.0%,m/m,以薯泥计）及pH（6、7、8）对马铃薯泥色泽、流变学特性、质构特性及微观结构等的影响规律。结果表明：随NaCl添加量的增加,马铃薯泥弹性由81.86%减小到79.40%、硬度由551.72 g增大到784.28 g,网络结构受到一定的破坏。随pH的增加,与pH为6时相比,马铃薯泥的弹性由81.44%减小到75.96%、硬度呈先降低后升高的趋势,稳定性减弱;当pH为6时,马铃薯泥弹性最大（81.44%）,硬度较小（528.84 g）,形成了致密的凝胶网络结构。综上所述,在不添加NaCl、pH为6时,马铃薯泥具有最佳的加工特性。该研究可为采用NaCl及调节pH制备适用于主食及休闲食品加工的高品质马铃薯泥提供理论依据。     

冷激处理对葡萄冻结特性的影响

为研究冷激处理对葡萄冻结品质的影响,以巨峰葡萄为研究对象,将其经0℃冰水混合物冷激10,30,60,90 min后冷冻处理,以冻结曲线、失重率、质构、颜色、细胞膜透性及可溶性固形物等为指标,探讨冷激处理对葡萄冻结特性的影响。结果表明,冷激30 min的葡萄通过0～-5℃的最大冰晶生成带的时间为416.7 s,而冷激10,60 min和90 min的葡萄通过的时间分别为794,496.3s和691.7s;冷激处理30 min的葡萄硬度、弹性、可溶性固形物含量显著高于其它组(P﹤0.05),而失重率和细胞膜透性则明显低于其余3个处理组(P﹤0.05)。相比未经冷激的处理组,适当的冷激处理在一定程度上提高葡萄的冻结品质。     

马铃薯泥对面团及面包品质的影响

为提高马铃薯的利用率,丰富主食面包的种类,选取5个不同品种的马铃薯样品,蒸熟后制成马铃薯泥,按30%的比例添加到面包粉中制作面包。通过分析混合面团的粉质、拉伸特性及发酵性能,研究添加马铃薯泥对混合面团流变学特性的影响;通过对马铃薯泥面包进行感官评价和仪器分析,探索添加马铃薯泥对面包品质的影响。结果表明,添加马铃薯泥后,混合面团筋力减弱,加工性能略有下降,但具有良好的持气能力和产气能力,发酵性能良好;添加马铃薯泥后所制面包体积变大,且不易老化,其中加入5号马铃薯样品的面包感官评价总分最高,面包切片亮度高于对照样品,且粗气孔体积得到改善。综合考虑面包的感官和物理特性,添加5号马铃薯样品做出的面包品质最好。     

不同冻结方式对汤圆品质特性的影响

为研究不同冻结方式对汤圆品质特性的影响,采用低温冰箱冻结、螺旋隧道冻结和液氮冻结三种方式,以汤圆中心温度降至-18 ℃为标准,对其失水率、亮度、煮后汤汁透光率、质构特性、糊化特性及感官评定等品质指标进行测定与分析。结果表明,三种冻结方式汤圆失水率、煮后汤汁透光率、硬度、弹性、咀嚼性、糊化特性均存在显著性差异(p<0.05)。低温冰箱冻结:汤圆失水率高、亮度及煮后汤汁透光率最低、硬度高且弹性小、咀嚼性差、淀粉糊化程度高、口感差;螺旋隧道冻结:汤圆失水率较高、亮度及煮后汤汁透光率较低、硬度较高且弹性较小、咀嚼性较差、淀粉糊化程度较高、口感较好;液氮冻结:汤圆失水率最低,亮度及煮后汤汁透光率最高,硬度最低且弹性最大、咀嚼性优、淀粉糊化程度最低,能更好保持汤圆的品质特性,口感最好。液氮冻结是优于低温冰箱冻结、螺旋隧道冻结的冻结方式,能较好的改善汤圆品质特性。     

送风参数对马铃薯泥冷冻特性的影响

利用Fluent软件建立马铃薯泥三维鼓风冷冻数值模型,研究冷冻时间对送风温度和速度的敏感程度,分析不同位置马铃薯泥冷冻条件和冷冻时间的不均匀度随送风参数的变化规律。结果表明,送风温度的改变对冷冻时间的影响比送风速度大。送风温度不变,随着送风速度的增大,马铃薯泥周围风速的不均匀度逐渐增大,温度的不均匀度逐渐减小,冷冻时间的不均匀度和中心温度的不均匀度随送风速度的增加呈现先减小后增大的趋势,送风速度为6 m/s时,二者最小。同一送风速度条件下,送风温度越低,马铃薯泥周围温度的不均匀度越小,中心温度的不均匀度越大。经验证,模拟结果与实验结果吻合较好,冷冻时间相对误差为3.27%,温度的平均绝对误差为0.79 K,均方根误差为2.11K。     

冻结温度对米发糕品质特性的影响

为研究不同冻结温度对米发糕品质特性的影响,采用-18、-30、-80、-196℃4种冻结温度处理,对冷冻曲线、失水率、质构特性、白度、淀粉老化、电子舌、电子鼻、GC-MS及感官评定等进行分析。结果表明：米发糕的冻结温度越低,越能有效缩短冻结时间,减小冻结损伤,降低失水率和米发糕的淀粉老化焓值。且-196℃组的白度值、质构特性与鲜样最接近,均显著优于其他3组(P<0.05)。此外电子舌与电子鼻的PCA图显示冻结温度越低,其主成分阈值越接近鲜样。GC-MS数据表示冻结处理会降低米发糕总体醇类物质含量,其中-80℃组的醇类含量最高。米发糕经冻结处理后复蒸,其感官评分会相应下降,冻结温度越低感官评分越高。结果表明,-196℃冻结可以更好地保持冷冻米发糕的品质特性。     

不同冻结方式对草鱼块品质特性的影响

本文以草鱼块为对象,比较了浸渍冻结(ICF)和传统空气鼓风冻结对草鱼块冻结品质的影响。试验结果表明:三元载冷剂浸渍冻结其冻结速率是相同温度下空气鼓风式冻结的1.54倍,是酒精溶液为载冷剂的浸渍冻结的1.28倍;采用三元载冷剂浸渍冻结后的样品和空气鼓风式冻结、酒精溶液冻结后的样品相比,前者盐溶性蛋白含量高于后两者,并且Ca2+-ATPase活性降低率、汁液流失率及蒸煮损失均低于后两者。综合各指标说明,浸渍冻结有利于减少鱼蛋白的变性,采用三元载冷剂浸渍冻结的草鱼块品质优于其他两种冻结方式。     

酶解马铃薯泥对馕质构和风味的影响

将不同比例的马铃薯泥(MP)、α-淀粉酶酶解马铃薯泥(α-AMP)和β-淀粉酶酶解马铃薯泥(β-AMP)分别与小麦粉复配制作馕,对比分析了不同类型马铃薯泥对馕质构和风味的影响.结果表明,随着MP或α-AMP添加量增加,馕内部的气孔逐渐减少,其质构品质变差;而添加β-AMP的馕内部保留了均匀气孔,添加10％或15％β-A...     

冷冻贮藏对马铃薯泥香气成分的影响

为探究马铃薯湿泥冷冻贮藏后口感、风味变化的原因,该试验利用冀张12马铃薯制备湿泥,通过电子鼻、电子舌及气相色谱-质谱联用对新鲜和-18℃冷冻30 d、4℃解冻12 h马铃薯泥的气味、滋味、香气成分进行测定比较。新鲜和冷冻贮藏马铃薯泥的气味、滋味、香气成分有一定差异,但有机硫化物、萜烯类、烃类、醇类和芳香族化合物在其中均含量丰富且挥发性大,是其香气的主要来源;冷冻贮藏过程降低了香气的浓郁度但并没有产生不良风味,在此过程中,苦味和咸味浓郁度未明显改变,有效降低了苦回味;冷冻贮藏过程损失了一部分香气成分的同时相较新鲜马铃薯泥产生较多的(10种)醇类物质。     

冻结速率对鸡汤理化及流变特性的影响

以新鲜鸡汤为对照,探究不同冻结速率(-20、-40、-80℃冻结)对鸡汤理化性质和流变特性的影响。结果表明,-20℃鸡汤冻结组属于慢速冻结,-40、-80℃鸡汤冻结组属于快速冻结。冻结处理会使pH、可溶性蛋白含量降低,电导率、L*值增加。慢冻组的电导率、硫代巴比妥酸值(thiobarbituric acid reactive substances,TBARS)可溶性蛋白和速冻组的pH、可溶性蛋白均与新鲜鸡汤差异显著(p0.05)。慢冻组与速冻组的电导率、TBARS差异显著(p0.05)。速冻组-40℃和-80℃的鸡汤除了电导率,其他理化指标均无显著差异(p0.05)。随剪切速率增加,鸡汤黏度值减小,剪切应力增大。剪切速率相同时,冻结组鸡汤表观黏度和剪切应力均低于对照组,-20℃慢速冻结对鸡汤流变影响较显著。速冻比慢冻对鸡汤溶液黏度、剪切力影响较小。综合分析,快速冻结更适合鸡汤冷冻处理。     

Viscoelasticity and microstructure of inulin-enriched mashed potatoes: Influence of freezing and cryoprotectants

The effect of the addition of inulin (0%, 1.5%, 3%, 4.5% and 6%) on viscoelastic properties and microstructure of fresh and frozen/thawed mashed potatoes (FMP and F/TMP, respectively) formulated without and with added cryoprotectants (kappa-carrageenan (κ-C) and xanthan gum (XG)) was investigated. Results showed that inulin concentration was the factor that set the minor difference among most of rheological properties, firmness and overall acceptability (OA) of the samples, whereas addition of κ-C and XG resulted in main differences between samples. Inulin effect on the thickening of the product was limited, which is mainly ascribed to a high heating temperature reached by the product during manufacture process inducing inulin hydrolysis. FMP samples presented more rigid structure than their F/TMP counterparts, although either inulin concentration or processing had much less significant effect on the viscoelasticity of the mashed potatoes containing cryoprotectants, evidencing the ability of this biopolymer blend to impart freeze/thaw stability.     

Rheological properties of mashed potatoes made from dehydrated flakes: effect of ingredients and freezing

 The rheological behaviour of mashed potatoes made from dehydrated potato flakes was studied using helical ribbon geometry, which enabled changes in the dynamic mechanical properties, as a function of ingredients concentration, to be followed. Mashed potatoes were also frozen in order to determine the changes that occurred in the cell structure. Response surface analysis was used to establish the empirical models for expressing the effects of significant ingredients on rheological properties. Results showed that both dynamic moduli (G′, and G") were significantly influenced by potato flake concentration (α<0.01) and the butter concentration (α<0.05 for G′ and a<0.10 for G″), while the salt concentration had a significant quadratic effect (α<0.05) on the storage modulus (G′). Significant interactions occurred between potato flakes and milk concentrations, and potato flakes and salt concentrations, and these were detected by the dynamic moduli. Breakdown of the cell wall by freezing decreased G′, G″ and η* values, showing that the frozen/thawed mashed potatoes consisted of dilute dispersions of swollen and disrupted intracellular starch granules. Received: 11 January 1999     

Effect of freezing/thawing conditions and long‐term frozen storage on the quality of mashed potatoes

The effects of freezing temperature (−80, −40 or −24 °C) and thawing mode (microwave or overnight at 4 °C) on quality parameters of mashed potatoes made from tubers (cv Kennebec) and from potato flakes were examined, as was the effect of long‐term frozen storage on the quality of mashed potatoes. Mashed potatoes were tested for texture profile analysis (TPA) and cone penetration, oscillatory and steady rheometry, colour, dry matter, Brix and sensory analyses. In natural mashed potatoes, TPA hardness and oscillatory parameters showed that processing resulted in a softer product than the fresh control. The parameters were lower in the samples thawed at 4 °C than in those thawed by microwave at all the freezing temperatures used, which may be ascribed to gelatinisation of the starch released from damaged cells. Differences from the freshly prepared product decreased when the samples were frozen at −80 °C and thawed by microwave. No difference was found in sensory acceptability between samples frozen at −80 and −40 °C, which probably reflects the panellists' mixed preferences for air‐thawed versus microwave‐thawed samples. Increasing the time in frozen storage led to a natural mash with a firmer texture, higher L*/b* value and Brix; nonetheless, panellists found the samples at 0, 3 and 12 months of frozen storage equally acceptable. In commercial mash, penetration and oscillatory parameters showed that processing made for a firmer product than the fresh control, probably owing to retrogradation of gelatinised starch. Thawing mode had a significant effect on parameters, which were lower in the samples thawed at 4 °C. The structure and quality of commercial mash was more detrimentally affected by freezing and, therefore, we would not recommend either freezing or frozen storage of this mashed potato in the used conditions. Natural mash made from Kennebec potatoes should be frozen quickly and thawed by microwave in the conditions described to obtain a product more similar to that freshly made. If the samples are frozen by air blasting at −40 °C, the product can withstand frozen storage for one year. Copyright © 2005 Society of Chemical Industry     

Effect of modified starch concentration and freezing and thawing rates on properties of mashed potatoes (cv. Kennebec)

Effects of modified cornstarch concentration, freezing rate and thawing mode on quality properties of mashed potatoes were examined. The product was tested by oscillatory rheometry, instrumental texture profile analysis (ITPA) and cone penetration, colour, dry matter (DM) and sensory analyses. Oscillatory parameters showed that increasing starch concentration resulted in a softer product in which gel strength decreased in direct proportion to concentration in quick‐frozen and microwave‐thawed product. Quick freezing made for firmer mashed potatoes, whereas oscillatory, ITPA and penetration parameters were lower in the samples thawed at 4 °C. Starch concentration and instrumental consistency and firmness were directly proportional to one another. Adding starch at the highest concentration, quick freezing and slow thawing produced a lighter‐coloured mashed potato, although the loss of colour in the processed product was not detected by panellists in the microwave‐thawed samples. DM was higher in the quick‐frozen samples and lower in air‐thawed samples. The factors studied affected different sensory texture parameters but had hardly any effect on attributes perceived during final and residual phases of mastication. Only starch concentration had a significant effect on sensory acceptability, but interactions between factors showed that starch addition followed by quick freezing was judged undesirable by the panellists due to excessive softening. Oscillatory parameters correlated well with sensory texture attributes and proved quite precise. They would therefore appear to be the best test to monitor properties of frozen mashed potatoes. Copyright © 2007 Society of Chemical Industry     

Effect of selected antioxidants on the stability of dehydrated mashed potatoes

The antioxidants TBHQ, alpha-tocopherol, Prolong P (rosemary, thyme, marjoram mixture) or ascorbyl palmitate were not found able to replace the antioxidant BHA in potato flakes production if stored for up to 24 months. Ascorbyl palmitate gave good antioxidative protection up to 16 months of storage, and also protected against carotenoid degradation better than the other antioxidants. The ascorbyl palmitate lost its antioxidative effect after longer storage.     

Enhancement of freezing stability in mashed potatoes by the incorporation of kappa‐carrageenan and xanthan gum blends

BACKGROUND: To ameliorate the detrimental effects of freezing and thawing, blends of κ‐carrageenan (κ‐C) and xanthan gum (XG) were added to frozen/thawed mashed potatoes (F/TM potatoes). Product was tested by textural and rheological measurements, other quality parameters and sensory analyses. The effects of variation in levels of κ‐C (1.5–4.5 g kg^?1) and XG (0.5–2.5 g kg^?1) concentrations were studied. RESULTS: Instrumental measurements and sensory analyses indicated that 4.5 g kg^?1κ‐C and 2.5 g kg^?1 XG provided better thickening. κ‐C provided the appropriate texture, while XG imparted creaminess to the product, which could be associated with an increase in the amount of XG–water interactions. Addition of κ‐C had a major impact on textural properties, gel strength and viscoelastic behaviour, whereas XG influenced steady properties, colour, water‐holding capacity (WHC) and overall acceptability (OA). CONCLUSION: The OA of F/TM potatoes was mostly improved by addition of cryoprotectant blends, which is ascribed to improvement of F/TM potatoes texture by retarding starch retrogradation, increasing WHC, and enhancing the principal characteristics determining consumer acceptance. Creaminess was the most crucial factor for OA of the products. Addition of both polysaccharides at a low concentration (each cryoprotectant at 1.5 g kg^?1) is recommended. Copyright © 2009 Society of Chemical Industry     

A rheological characterisation of mashed potatoes enriched with soy protein isolate

The effect of the addition of soy protein isolate (SPI) (0, 15, 30, 45 and 60 g kg⁻¹) on viscoelastic properties, large deformation measurements and microstructure of fresh (FM) and frozen/thawed (F/TM) mashed potatoes was investigated. Rheological data showed weak gel behaviour for both FM and F/TM potatoes without and with added SPI together with a significant decrease of system viscoelasticity (G′ and G″) with increasing SPI volume fraction, primarily attributed to the no interaction between the amylose/amylopectine matrix and the dispersed SPI particles or aggregates as revealed by scanning electron microscopy (SEM). Micrographs also showed that SPI formed white coarse aggregates. A freeze/thaw cycle produced a more significant decrease in viscoelastic functions, due to superior aggregation of denatured SPI and reduced water activity. In F/TM samples, high correlations between small and large deformation measurements were found. Results may be useful for technological applications in SPI-enriched mashed potatoes.     

冻结方式对油条品质特性的影响

探究冻结方式对油条水分分布及品质特性的影响。采用液氮浸渍冻结(liquid nitrogen freeze, LF)、螺旋隧道冻结(spiral tunnel freeze, SF)及低温冰箱冻结(refrigerator freeze, RF)3种方式分别对油条进行冻结,测定冻结后油条水分含量、T_2弛豫时间、复炸后油条的色泽及比容、质构特性和感官品质。冻结方式对油条水分含量有显著影响(P<0.05),对L~*值、a~*值、色差△E有极显著影响(P<0.01);LF和SF处理油条内瓤结合水含量极显著高于RF(P<0.01),自由水含量显著低于RF(P<0.05);LF处理油条组织水分迁移最少,复炸后比容最大,表皮色泽、组织酥软性较好,组织孔隙较均匀,质构特性较优,最接近新鲜油条感官品质。液氮冻结处理油条品质较优,有望成为工业生产油条的新型冻结技术,为速冻油条生产提供了科学参考。