Acrylamide in potato crisp—the effect of raw material and processing

Reducing sugars and free amino acids were analysed in slices from three potato cultivars before and after blanching (0-3 min). The potato crisps were deep fried at 185 °C for different times (3-8.5 min), and analysed for the concentration of acrylamide (AA) and moisture. Potato cultivar and the temperature during processing were important parameters for AA formation in potato crisps. The amount increased with an increase in the processing time. Blanching before deep-frying reduced the concentration of free asparagine and reducing sugar in the raw material. We found no effect of blanching as pretreatment on the concentration of AA in the potato crisps. Any relationship was not detected between the levels of asparagine in the different cultivars, before and after blanching, and the formation of AA in the crisp products. However, it was shown that the content of reducing sugars determined the level of AA after frying.     

KINETICS ON COLOR CHANGES DURING DRYING OF SOME FRUITS AND VEGETABLES

Abstract

The effect of drying conditions on color changes of apple, banana, carrot and potato during conventional and vacuum drying was investigated. The Hunder color scale parameters redness, yellowness and lightness were used to estimate color changes during vacuum and conventional drying at 50, 70 and 90°C. Air humidity during conventional drying was regulated at 15, 30 and 40%. Air temperature and humidity affected redness and yellowness, but not lightness. A first order kinetic model was fitted to experimental data adequately for both redness and yellowness. The rate of color deterioration was found to increase as temperature increased and air humidity decreased, for both drying methods and all the examined materials.     

Effect of Vacuum-Microwave Predrying on Quality of Vacuum-Fried Potato Chips

The effects of vacuum microwave predrying on the quality of vacuum-fried potato chips were studied. The results showed that vacuum microwave predrying had a significant effect on moisture and oil contents, as well as color parameters and structure of potato chips. Vacuum microwave predrying significantly decreased the oil and moisture contents of vacuum-fried potato chips. The rates of both mass transfer phenomena (water loss and oil uptake) that take place during the vacuum frying of potato chips decrease due to the vacuum microwave predrying. The vacuum microwave predrying had a negative effect on color of potato chips, which decreases the L value of potato chips and increases Hunter a and b values. Breaking force of fried potato chips is also significantly (P < 0.05) affected by the drying pretreatment, which decreases the breaking force at the beginning of predrying and then increases with vacuum microwave predrying time.     

Simulation of Liquid Diffusion-Controlled Drying of Shrinking Thin Slabs Subjected to Multiple Heat Sources

Abstract

Although a detailed mathematical model incorporating all physical mechanisms of moisture and heat transfer in the material would yield valuable design information, it is not feasible to do this on a routine basis for the design of dryers. A simple liquid diffusion model was developed in the present study to quantitatively assess the influence of various operating parameters of engineering interest in drying of heat-sensitive materials. Heat of wetting, temperature, and moisture dependent effective diffusivity and thermal conductivity, changes in product density and drying-induced ideal shrinkage of the product are considered in this model. The effects of combining convection with conduction, radiation, and volumetric heating using a microwave field are simulated in view of the increasing interest in multimode heat input drying processes. Numerical results are reported on drying of potato slices to demonstrate how the moisture and temperature profiles as well as drying performance are affected by multi-mode heat input. Effects of key parameters e.g., drying air velocity, temperature, relative humidity, and product thickness are computed and discussed.     

A Mathematical Model for Vacuum Far-Infrared Drying of Potato Slices

A mathematical model of mass and heat transfer for vacuum far-infrared drying of potato slices is introduced in this study on the basis of energy and diffusion equations. The finite difference method is used to mathematically simulate the sample temperature and moisture content in different drying conditions. Calculated results are compared with the experimental findings at varying conditions of heater temperature (120°C, 140°C, and 160°C), chamber pressure (1500, 8000, and 15000 Pa), sample thickness (0.004, 0.006, and 0.008 m), and radiation distance (0.08, 0.12, and 0.16 m). Comparison results show that the model fits well the changes in sample temperature and moisture content at different times of drying, with the values of the coefficient of determination close to 1.0 and the relative error values less than 10%.     

KINETICS ON COLOR CHANGES DURING DRYING OF SOME FRUITS AND VEGETABLES

The effect of drying conditions on color changes of apple, banana, carrot and potato during conventional and vacuum drying was investigated. The Hunder color scale parameters redness, yellowness and lightness were used to estimate color changes during vacuum and conventional drying at 50, 70 and 90°C. Air humidity during conventional drying was regulated at 15, 30 and 40%. Air temperature and humidity affected redness and yellowness, but not lightness. A first order kinetic model was fitted to experimental data adequately for both redness and yellowness. The rate of color deterioration was found to increase as temperature increased and air humidity decreased, for both drying methods and all the examined materials.     

TMV、PVY福建分离物分子鉴定及末端区域变异分析

为及时准确地鉴定出病毒病原和追踪了解病毒病流行变异趋势,使用特异性引物对福建烟区病毒烟叶样品进行RT-PCR分析,分别鉴定出病毒病原为TMV和PVY.序列测定结果表明PCR扩增产物为预期的TMV 5'末端和PVY 3'末端序列,大小分别为959和646个核苷酸,均包含末端非编码区和部分病毒功能基因蛋白编码区.将所获得的病毒末端序列与国内外报道的主要病毒分离物的同一区域进行比较,分析结果显示TMV 5'端非编码区保守性极强,不同分离物之间部分126 kDa或183 kDa编码蛋白N端编码区表现出一定程度的变异(突变),PVY外壳蛋白编码区与3'末端非编码区变异数量差异不大,变异(突变)均主要为碱基转换,环境自然选择压力对病毒基因组变异(突变)具有一定的影响.     

Energy inputs and crop yield relationship in potato production in Hamadan province of Iran

The aim of this study was to determine energy consumption and the relationship between energy input and yield for potato production in Kaboud Rahang region of Hamadan state. The data used in this study are collected by questionnaire. The results revealed that nitrogen fertilizer (39%), diesel (21%), seed (14.9%), water (7.5%) and manure (6.4%) consumed the bulk of energy. In the surveyed farms, average yield and energy consumption were calculated as around 28613.7 kg/ha, 92296.3 MJ/ha, respectively. The results also showed that energy ratio, specific energy and energy productivity were 1.1, 3.2 MJ/kg and 0.3 kg/MJ, respectively. An econometric model was developed to estimate the impact of energy inputs on yield by using parametric methods. For this purpose, potato yield, an endogenous variable was assumed to be a function of energy inputs: fertilizer manure, chemical, machinery, human, water for irrigation, diesel and seed. The empirical results indicated that variables: fertilizer, chemical, seed and human were found statistically significant and contributed to yield. Among statistically significant exogenous variables, seed, water for irrigation, chemical, human and fertilizer were ranked in terms of elasticities.     

Sulphated and carboxymethylated polysaccharides from Lycium barbarum L. leaves suppress the gelatinisation,retrogradation and digestibility of potato starch

Processing starch with polysaccharides promotes broader applications, and it is important to consider all possible structural interactions among the molecular ingredients. In this study, polysaccharides isolated from Lycium barbarum L. were chemically modified by sulphation (SLP) and carboxymethylation (CLP), and the effects on the gelatinisation, retrogradation, and digestibility properties of the potato starch were investigated. After chemical modification, the slope of the curve between the molar mass and molecular radius of polysaccharides decreased, revealing that the relatively rigid rod-like structure of native polysaccharide (0.78) changed to SLP's random linear chain (0.53) and CLP's spherical conformation (0.23), and the water solubility increased from 63.6% to 70.4% (SLP) and 84.1% (CLP) in distilled water at 25 °C. Moreover, testing polysaccharides as an additive indicated that both derivatives significantly decreased the peak viscosity, breakdown, and setback viscosity during potato starch pasting. Furthermore, the possible interactions could be further examined by structure analyses, suggesting the polysaccharide and SLP hydrogen bonds interacted with the surfaces of starch granules, while CLP penetrated the interiors of pasted starch granules, destroyed the helixes and backbone structure of starch, and formed type V crystallinity with amylose. The results of in vitro digestion analysis revealed that polysaccharides could decrease the amount of resistant starch and increase the amount of slowly digestible starch, which might be related to the inhibition of starch gelatinisation. These results facilitate the application of chemical derivatives in starch-based functional foods and understand the interaction mechanism between potato starch and polysaccharides.     

How circular will you eat? The sustainability challenge in food and consumer reaction to either waste-to-value or yet underused novel ingredients in food

In the light of the sustainability challenge ahead, the food sector has to become more resource efficient. This includes moving towards a circularity approach in which by-products from production side-streams are re-inserted into the food chain. However, it is unclear how consumers react to food products based on ingredients previously wasted in the supply chain, or innovative food ingredients from yet underused production streams. The current study uses an experimental survey design to assess consumer attitude towards a plant-based cocoa drink among 491 Danish consumers of cocoa-flavoured drinks. In a between-subjects design, the product is first, either from the market leader in plant-based drinks or from an unfamiliar, non-Danish brand, second, contains either potato or grass protein, and third, is presented with or without communication on the sustainability benefit. The benefit consists of potato protein being from by-products previously wasted, and grass protein an innovative ingredient yet underused for food purpose. Attitude towards the new product is assessed relative to a soy based cocoa drink of the same brand. ANOVA results show a main effect of gender and brand and an interaction of ingredient with both brand and communication, respectively. For both grass and potato proteins, the unknown brand is relatively preferred – more pronounced for potato – and better liked by males. Communication improves attitude towards potato drink. Findings imply that brand- and product design-related differences play a role in determining attitude to products with such new ingredients. Consumers’ relatively lower attitude towards the potato ingredient can be alleviated by communication.