Dielectric Properties of Mashed Potatoes Relevant to Microwave and Radio-frequency Pasteurization and Sterilization Processes

ABSTRACT: Dielectric properties of mashed potatoes relevant to microwave and radio-frequency (RF) pasteurization and sterilization processes were measured over 1 to 1800 MHz and 20 °C to 120 °C. Effects of moisture content (81.6% to 87.8%, wb) and salt content (0.8% to 2.8%, wb) were investigated. Dielectric loss factors and constants decreased with frequency. Dielectric loss factors increased with temperature and salt content, but dielectric constants were not significantly affected. Ionic conductivity played a dominant role at low frequencies. Power penetration depth increased with moisture content and decreased with temperature, frequency, and salt content. Regression equations were developed to relate the dielectric properties to temperature, moisture, and salt contents.     

Reproducible Texture Analysis of Potato Chips

An Instron punch test with three point support of a potato chip was developed, and factors affecting the results were evaluated. Individual potato chips were fried in palm oil in a forced circulation glass container, and their moisture content and texture were determined. Sample handling parameters contributing most to variability of moisture and texture were the cutting device, and position of the sample within the tuber. For oil temperatures 140 and 180°C, and two potato specific gravities, moisture and texture changes were studied during frying. Maximum force of break was in the 2–4% moisture region. Individual chips showed highly variable room temperature adsorption/desorption.     

复合薯片生产中的几个问题

经过近十年的发展,我国的复合薯片从无到有发展为一个制造业,形成了工艺研究,新产品开发,生产及流通管理的体系,但主要设备依赖进口。休闲食品行业还存在哪些问题,今后如何发展,是本行业专家及企业家十分关注的问题。 一、原材料质量控制 (一)衡量复合薯片原材料的重要指标 马铃薯粉是生产复合著片的主要原材料,控制马铃薯粉质量才能保证产品质量。生产企业必须从两方     

Classification of Potato Chips Using Pattern Recognition

ABSTRACT: An approach to classify potato chips using pattern recognition from color digital images consists of 5 steps: (1) image acquisition, (2) preprocessing, (3) segmentation, (4) feature extraction, and (5) classification. Ten chips prepared for each of the following 6 conditions were examined: 2 pretreatments (blanched and unblanched) at 3 temperatures (120°C, 150°C, and 180°C). More than 1500 features were extracted from each of the 60 images. Finally, 11 features were selected according to their classification attributes. Seven different classification cases (for example, classification of the 6 classes or distinction between blanched and unblanched samples) were analyzed using the selected features. Although samples were highly heterogeneous, using a simple classifier and a small number of features, it was possible to obtain a good performance value in all cases: classification of the 6 classes was in the confidence interval between 78% and 89% with a probability of 95%.     

Effect of Raw Potato Composition on Acrylamide Formation in Potato Chips

ABSTRACT: Recent studies have shown that subjecting foods to high temperatures during cooking processes such as frying gives rise to the formation of acrylamide. Several factors including product composition and processing conditions affect the rate of formation of this chemical in starch-rich foods. Low reducing sugar and the amino acid asparagine content is desired when cooking because the formation of acrylamide is attributed to the Maillard reaction that occurs between these food components. The cultivar 'Atlantic' was used to determine the effect of potato components (reducing sugars and asparagine) on acrylamide content during frying in a traditional fryer. A model system was developed by infusing leached potato slices with predetermined amounts of glucose and asparagine. Increasing glucose and asparagine content in the slices increased the acrylamide content in the potato chips. Color could not be used as an indication of acrylamide content because potato chips with similar color had very different acrylamide concentrations.     

复合薯片加工工艺及其专用设备

介绍了复合薯片生产用原料的特性及其改性机理、生产工艺控制经验、专用设备设计更加契合工艺要求。其工艺和设备在技术上都有很大的突破     

Studying Oil Absorption in Restructured Potato Chips

ABSTRACT: The oil-absorption capacity of different restructured potato chips during deep-fat frying was investigated. Low-leach potato flake was chosen as the major ingredient, whereas native and pregelatinized potato starches were studied as complementary ingredients. Results showed that oil absorption increased significantly when reducing product thickness in all products. Interestingly, it was found that the product containing native potato starch as an ingredient picked up the lowest amount of oil when sheeted into a thick chip, whereas it absorbed the largest amount of oil when sheeted into a thin chip. Those findings were mainly attributed to crust microstructure development as revealed by electron microscopy and confocal microscopy.     

不同马铃薯品种对鲜切油炸薯片中丙烯酰胺的影响

研究11个不同马铃薯品种,在相同的油炸条件下进行鲜切油炸薯片实验,采用液相-质谱联用检测其不同品种鲜切油炸薯片的丙烯酰胺含量,结合品种的还原糖含量,对丙烯酰胺含量进行分析。方法：热烫60s,表面干燥,180℃油炸100s,脱油,样品预处理,待测。结果：在相同油炸实验的基础上,检测出丙烯酰胺含量较低的是D519、陇薯3号、中薯7号、LK99等;丙烯酰胺含量较高的是中薯8号、夏波蒂、中薯3号等,并且丙烯酰胺含量与品种的还原糖含量走向基本相似。     

加工工艺对油炸马铃薯片品质的影响

本文研究了油炸马铃薯片加工过程中切片预干燥时间、油炸温度和不同浸泡处理对油炸马铃薯片品质的影响,通过薯片炸前炸后色泽变化、亮度、丙烯酰胺含量、水分含量、含油量及感官指标等理化指标进行评估。结果表明,油炸马铃薯片的色泽变化和丙烯酰胺含量随油炸温度升高增大,预干燥时间越长切片炸前水分含量越低,油炸时间越短,但随着预干燥时间的增加油炸薯片色泽变化也越大。油炸马铃薯片的最佳生产工艺为:鲜切马铃薯片先在85℃清水中热烫3.5 min,再用0.3%CaCl2溶液中室温浸泡30 min,浸泡后切片在60℃下热风干燥箱干燥15 min,130℃油炸即可得到色泽变化最小、丙烯酰胺含量低的油炸薯片。     

Textural and Rheological Properties of Cooked Potatoes

Cooked potato samples of different cultivars and specific gravities were analyzed for textural and rheological properties by sensory evaluation, texture profile analysis (TPA) and stress relaxation tests. Mealiness was correlated with the product of cohesiveness and adhesiveness, but not with other TPA parameters. Stress relaxation tests of cooked potatoes yielded a Maxwell model consisting of two viscous and three elastic elements. One of the elastic moduli was correlated with mealiness. Hardness by sensory evaluation correlated well with hardness and fracturability by TPA, and with the three elastic moduli in the relaxation model.     

Acrylamide Mitigation in Potato Chips by Using NaCl

In April 2002, Swedish researchers shocked the world when they presented preliminary findings on the presence of acrylamide in fried and baked foods, most notably potato chips and French fries, at levels of 30–2,300 ppb. The objective of this research was to study the effect of immersing potato slices in a NaCl solution over the acrylamide formation in the resultant potato chips. Potato slices (Verdi variety, diameter 40 mm, width 2.0 mm) were fried at 170 °C for 5 min (final moisture content of ∼2.0%). Prior to frying, the potato slices were treated in one of the following ways: (1) control slices (unblanched or raw potato slices); (2) slices blanched at 90 °C for 5 min in water; (3) slices blanched at 90 °C for 5 min plus immersed in a 1 g/100 g NaCl solution at 25 °C for 5 min; (4) slices blanched at 90 °C for 5 min plus immersed in a 3 g/100 g NaCl solution at 25 °C for 5 min; (5) slices blanched at 90 °C for 5 min plus immersed in distilled water at 25 °C for 5 min; and (6) slices blanched at 90 °C for 5 min in a 3 g/100 g NaCl solution. Blanching followed by the immersion of potato slices in 1 g/100 g NaCl solution was effective in reducing acrylamide content in ∼62%; however, almost half of this percentage (∼27%) could be attributed to the effect of NaCl and 35% to the effect of the slight heating treatment during salt immersion step (25 °C for 5 min). Blanching seems to make the NaCl diffusion in potato tissue easier leading to a significant acrylamide reduction in the potato slices after frying.     

Dielectric Properties of Potato Puree in Microwave Frequency Range as Influenced by Concentration and Temperature

Dielectric properties of potato flour-water dispersions (slurry) were measured in the frequency range of 500–2500 MHz by the open-ended coaxial probe method using a network analyzer as a function of concentration (10–25% w/w) and temperature (20–75^oC). Both commercial and laboratory prepared samples of potato flours were used. Results indicated that the dielectric constant (ε′) decreased with temperature and frequency while increased with concentration. The loss factor (ε″) increased with frequency and concentration; however, temperature showed mixed effect. Both ε′ and ε″ data in conventionally used microwave frequencies (915 and 2450 MHz) were studied as function of concentration and temperature for two sample types using a response surface methodology and found to follow 2^nd order polynomial models. Temperature and concentration contributed significantly on dielectric spectra of potato slurry and the sample source had some effect. A change in ε′ and ε″ above 70^oC could be attributed by starch gelatinization. Penetration depth (D_p) decreased with an increase in frequency and non-systematic with temperature. Addition of salt substantially reduced D_p of potato slurry.     

煎炸油在薯片煎炸过程中的品质变化

以煎炸油为研究对象,以薯片为煎炸原料,研究煎炸油煎炸过程中理化指标变化及各指标间的相关性。结果表明:在煎炸过程中,煎炸油的折光指数、色泽、酸值、羰基值和极性值均随时间的延长而增大;过氧化值随着煎炸时间延长先增大后逐渐减小;碘值随时间的延长而降低;比重、黏度、皂化值在煎炸过程中的变化无明显规律。酸值、羰基值、极性值、色泽和折光指数彼此之间有极显著的正相关性,且相关系数均大于0.9;煎炸油极性值的变化可通过色泽和酸值进行预测。     

真空油炸马铃薯脆片预处理工艺优化

为优化马铃薯脆片的预处理工艺,采用单因素和响应面试验,以破碎力、含油量、L*值、感官评分、综合评分和电子鼻检测挥发性成分为指标,对实验数据进行主成分分析。结果表明:不同的预处理方式对马铃薯脆片的破碎力、感官评价和综合评分有显著影响(p0.05)。主成分分析共提取5个主成分,前3个主成分总贡献率大于85%,说明提取3个主成分能够全面反映马铃薯脆片的品质信息,决定第1主成分的指标主要是感官评价和综合评分,决定第2主成分的是破碎力和含油量;决定第3主成分的是L*值和含油量。以主成分分析得到的规范化综合得分为响应值建立的二次多项式回归模型回归效果极显著(p0.01,R~2=0.9604)。确定最佳工艺参数为漂烫温度91℃、漂烫时间4 min、切片厚度4 mm和冷冻时间3 h,在此条件得到规范化综合评分0.9572,与预测值(0.9453)相接近,表明以主成分分析得到的规范化综合评分为响应值建立的回归模型具有良好的预测能力。     

Contribution of Sucrose to Nonenzymatic Browning in Potato Chips

The contribution of sucrose, a nonreducing sugar, to nonenzymatic browning in potato chips was investigated using a model system of buffered sugars and glycine applied to filter paper discs that were then heated in oil. It was found by fiber optic colorimetry that sucrose and the amino acid produced darkening comparable to that of reducing sugars. It is postulated that sucrose enters the reaction by thermal hydrolysis to yield glucose and fructose. Addition of glucose and glycine to potato slices by vacuum infiltration resulted in increased darkening after frying but the sugar proved to be the limiting factor in nonenzymatic browning of potato chips, emphasizing the importance of sucrose in this reaction.     

甘薯微波膨化脆片的工艺优化

为优化微波膨化甘薯脆片的工艺条件,笔者以甘薯品种、切片厚度、初始含水量、漂烫时间、微波强度及膨化时间等为因素,以色泽、膨化率、断裂力、感官评分等为考核指标,采用正交试验设计法进行研究分析。结果表明:初始含水量、切片厚度、微波强度及膨化时间和品种为主要影响因素,得出微波膨化甘薯脆片的最佳工艺条件为:品种"山东紫薯",纵向切片厚度2.0mm,沸水漂烫180 s,含水量15%,微波强度2.3 W/g,膨化时间50 s;品种"福建黄心",纵向切片厚度2.5 mm,沸水漂烫180 s,含水量15%,微波强度2.3W/g,膨化时间50s。在该工艺条件下得到的甘薯脆片色泽、口感、质地俱佳,膨化效果好,为甘薯的开发利用及甘薯脆片品质的改善提高提供了有效借鉴与参考。     

马铃薯片热风干燥特性及收缩动力学模型

为提高马铃薯片的热风干燥效率及品质,控制其干燥过程中的收缩变形,本文研究了不同热风温度（45、55、65、75 ℃）和切片厚度（3、5、7、9 mm）对马铃薯片热风干燥特性曲线、有效水分扩散系数及活化能等指标的影响。结果表明,干燥室内热风温度越高、马铃薯切片厚度越小时,干燥速率越快。在研究范围内,马铃薯片的有效水分扩散系数在5.02×10?10~11.53×10?10 m2/s范围内,其值随热风温度升高或切片厚度减小而增大。此外,研究发现Weibull分布函数能够很好地描述马铃薯片的降速干燥过程和收缩动力学模型。通过Arrhenius方程计算得到马铃薯片的干燥活化能和收缩活化能分别为27.35和46.44 kJ/mol,马铃薯片干燥比收缩消耗活化能少。本研究为马铃薯片在热风干燥加工中水分迁移和体积收缩变化的预测提供了理论依据和技术支撑。     

L-半胱氨酸对油炸薯片中有害醛、晚期糖基化终产物的抑制作用及其品质的改善效果

采用不同质量浓度（1、3、5 mg/mL）的L-半胱氨酸（Cys）溶液浸泡鲜切马铃薯片后油炸,结果表明,添加Cys后可显著降低油炸薯片中乙二醛、丙酮醛、3-脱氧葡糖醛酮和5-羟甲基糠醛的含量,由二羰基化合物产生的晚期糖基化终产物也显著降低。同时发现,添加Cys后,油炸薯片中油脂的酸值、过氧化物值和羰基价也呈下降趋势。Cys还会影响油炸薯片的风味,其中挥发性醛类和醇类风味物质含量增加,但吡嗪类风味物质含量减少。由12 名小组成员对不同Cys处理组的油炸薯片进行感官评定表明Cys溶液浸泡处理的油炸薯片的接受度高于非浸泡对照组。     

不同品种马铃薯雪花粉在方便土豆泥中的应用比较

东农310为本土培育的适用于全粉加工的马铃薯品种,该研究以引进生产全粉马铃薯品种大西洋为对照,从营养物质/质构/挥发性风味物质/感官评价分析了东农310马铃薯雪花粉在土豆泥中的应用。研究表明东农310雪花粉的干物质、蛋白和淀粉含量较低。矿物质元素中钙含量低于大西洋,但磷、铁、镁、钾含量都高于大西洋,吸水性略低大西洋雪花粉。东农310雪花粉颜色外观与大西洋相比,白度基本一致,黄绿色较深。添加相同比例雪花粉时大西洋质地和粘聚性更接近于市售土豆泥粉所制作土豆泥,但东农310土豆泥质地更软且粘聚度低,感官评价更适口。GC-MS香气成分检测,东农310醛类物质含量明显高且气味阈值低,是土豆泥的关键性香气物质。综合分析认为,东农310雪花粉制作的土豆泥营养成分丰富、整体风味浓郁,且质地软,略微提高其比例则可接近市售土豆泥质地,适用于加工为土豆泥。