Rehydration of Dehydrated Foods

Dehydrated products readily take up moisture when immersed in a liquid medium, leading to significant changes in their thermophysical properties. The rehydration kinetics, the structural properties (apparent density, true density, specific volume and internal porosity), the viscoelastic behavior (compression tests), and the flavor losses were investigated during rehydration of various fruits and vegetables. The effect of temperature on the above properties was also investigated for some fruits and vegetables dehydrated by different drying methods (convective, vacuum, freeze, and osmotic drying). The results showed that the water temperature influences the rehydration kinetics and the equilibrium moisture content of the rehydrated. The structural properties of rehydrated foods appear to show a hysteresis compared to those measured during dehydration processes. The shrinkage that takes place during dehydration prevents rehydration and produces products with lower apparent density and higher porosity. Structural damages that occur during drying seem to affect also the viscoelastic behavior of the rehydrated foods and the hysteresis phenomenon is also observed at the textural properties, with a degree varying between the different drying methods. More specifically, freeze-dried materials present the highest hysteresis after rehydration, losing their elasticity and becoming more viscous. Osmotic pretreatment seems to help freeze-dried materials to keep their elastic nature probably due to solids gain. Air- and vacuum-dried materials showed the smallest hysteresis tense, keeping their viscoelastic characteristics during rehydration close to those of dried materials. Flavor losses seem to have lower rates during rehydration comparing to those observed during drying. The maximum retention of flavor has been observed in the rehydrated products after freeze-drying, and flavor levels are close to those observed for fresh boiled foods.     

Vegetables and legumes in new Australasian food launches: how are they being used and are they a healthy choice?

Background

Despite the health benefits of regular vegetable and legume consumption, on average Australians are consuming only half of the recommended daily intake. The reasons for this low consumption are complex, and are particularly driven by societal shifts towards convenient and ready-to-eat meal options. It is currently unknown how legumes and vegetables are being utilised in food products within the Australian context, and the nutritional value or level of processing of these products.

Methods

The Mintel Global New Food Database was used to identify all new products launched between May 2012 and May 2017 in Australasia which at least 0.5 serves of vegetables and/or legumes per recommended serving. Eligible products were coded using the NOVA food classification system and the Healthy Choices guidelines, and were categorized by the researchers based on the type and proportion of vegetable and legume ingredients used.

Results

Overall, 1313 products were identified, which contained a median of 55% vegetable and legume ingredients (IQR?=?45%). This translated to approximately 1 (IQR?=?1) serves of vegetables and legumes per recommended serving of the products. The product launches were most likely to be classified as an ‘amber’ choice, and be classified as either ‘processed’ or ‘ultra-processed’. Vegetables and legumes were mainly found in the form of new prepared meals, soups or whole vegetables products, however there were some more innovative uses of these ingredients, such as yoghurts and pastas.

Conclusions

Most of the new products currently released onto the Australian market which contain vegetable and legume ingredients do not provide meaningful amounts of these ingredients, and tend to be highly processed and unhealthier options. A multi-faceted approach is needed to improve vegetable and legume consumption, which includes improving the availability of products which help consumers to meet vegetable and legume consumption recommendations. Future research should consider the acceptability of these products to consumers, and the barriers for food manufacturers in creating products with a higher amount of vegetables and legumes.

     

Effects of Pretreatments of Sliced Vegetables with Trehalose on Drying Characteristics and Quality of Dried Products

Effects of pretreatments with trehalose on drying of sliced vegetables (potato and carrot) were experimentally investigated. Two different pretreatment methods were tested. Sliced vegetables were steam-blanched and then immersed in a sugar solution. In another method sliced vegetables were coated with sugar powder, and then steam-blanched. Solid gain and water loss during pretreatment were measured. The isothermal drying experiments were carried out at 303, 313 and 323 K. Sorption isotherms of dried samples were determined by a standard gravimetric method at 303, 313 and 323 K. Pretreatments reduced the water content of vegetable samples due to osmotic dehydration. Less shrinkage, better colour properties and better cell reconstruction properties were observed for samples pretreated with trehalose either with solution or with powder.     

Hydrolyzed and autolyzed vegetable proteins as functional food ingredients

Hydrolyzed vegetable or plant protein (H.V.P. or H.P.P.) can be defined as mixtures containing amino acids and frequently other substances such as salt and peptides, obtained by hydrolysis of vegetable proteins. On an industrial scale two types of hydrolytic processes are applied: acid and enzymic hydrolysis. HVP estimated sales in the western world are at least $100 million. Most HVPs are produced for internal use by soup manufacturers, for use as vital meaty or savory flavoring ingredients in bouillons, soups, sauces, processed meat, fish and poultry products and snacks. Other HVPs are more ready-made products, or have obtained additional meat flavor value by careful blending and/or by processes based on Maillard-type reactions. Of substantially less importance is the use of HVP as whipping, foaming or areating agent, as nutritional ingredients or as bread or baking improver. Most of the HVPs used for these purposes are only partially hydrolyzed by enzymes or by alkaline treatment. The legal status of HVP, food ingredient or food additive, and its safety was discussed recently at various locations. So far these discussions have resulted in the tentative conclusions that HVPs are food ingredients which need standardization, and which, at their presently used levels, can be considered as being GRAS.     

Lipolytischer Fettverderb in Currygewürzmischungen – Eignung einer fluorometrischen Lipasebestimmung zur Qualitätsbewertung

Lipolytic Fat Deterioration in Carry Spice Mixes – Suitability of Fluorometric Lipase Determination for Quality Evaluation To improve quality and shelf life of fat containing dry mixtures (e.g. soups, sauces) treated spice mixtures are increasingly used in the industry. By a hydrothermic treatment (i.e. moist heat/steam) an enzyme inactivation of spices beside a germ reduction is observed. The evidence for Lipase activities (which cause hydrolytic fat deterioration) in curry mixtures could be shown within 3 different methods: A Fluorometric method based on 4-methylumbelliferylesters as substrates is suitable for proving a thermic treatment in different curry spice mixtures. When compared to a true Lipase measurement (incubation test with coconut fat as substrate) and to a socalled Esterase-test according to Purr it could be clarified that all 3 methods give corresponding results. Treated curry mixtures are almost fully inactivated, whereas untreated curry mixtures show considerable lipase activity. With the fluorometric method, which is quickly carried out, very low residual activities are shown. This is not possible with the Esterase-test. The incubation test also sensitively demonstrates Lipase, but takes a longer time to evaluate.     

Interfacial tensions of vegetable oil/water systems: Effect of oil purification

Methods were developed to determine the interfacial tension (IT) of vegetable oil/water systems as a function of time, and to remove interfacially active contaminants from commercial vegetable oils. Interfacial tensions between commercial vegetable oils and water decreased with time due to the presence of impurities. Interfacial tensions of purified oils against water were substantially higher than those reported in the literature, and remained unchanged with time, thereby indicating the absence of surface chemical impurities in the oil. The lowering of IT in the case of commercial oils was ascribed to the presence of mixtures of monoglycerides.     

Dietary intake of Senegalese adults

The aim of this work is to identify major food sources and dietary constituents of Senegalese adults. We conducted a cross-sectional study, using a single 24-hour dietary recall interview. Foods were classified into food groups based on similarities in nutrient content or use. Food groups included foods consumed individually, or as part of food mixtures such as stews, soups, or sandwiches. Median consumption (amount/day) of each food was determined and examined by relevant subgroups. Participants were 50 healthy Senegalese men, aged 20-62 years recruited at the Hôpital Général de Grand Yoff in Dakar, Senegal and from Sendou village, a rural area outside Dakar. A total of 90 foods and beverages were identified and classified into 11 groups. Sixty-five percent of foods identified could be classified as meats, grains, or fruits/vegetables. Fruits and vegetables comprised 42% (38/90) of all foods; meats 12% (11/90); and grains 11% (10/90). Sauces (6%, 5/90), sweets (4%, 4/90), and desserts (4%, 4/90) were also reported. The most common fruits/vegetables reported were potato, carrot, mango, and lettuce; commonly reported grains were bread and rice; and commonly reported meats were fish, beef, and ox. There were no differences in reported daily intake of each food by age, ethnicity, education, or residence. Most foods reported were traditional to the Senegalese diet, despite the increasing availability of Western foods in Senegal.     

Effects of Acetic Acid Pretreatment and Hot Air Drying on Resistance of Salmonella on Cabbage Slices

The heat resistance of Salmonella anatum inoculated onto the surface of cabbage slices as affected by acetic acid pretreatment (0.5–1.5% v/v) and hot air drying at 50–60°C was investigated. Approximately 1.5 log₁₀ of Salmonella numbers was reduced after soaking the vegetables in acetic acid solution. The inhibitory effect of acetic acid on the bacteria was more pronounced during drying. The heat resistance of Salmonella on the cabbage surface treated with acetic acid decreased considerably compared with untreated cabbage. Moreover, the vegetable treated with higher acetic acid concentration resulted in a higher degree of acid injury and hence increased the susceptibility to heat during drying. The results revealed that acetic acid pretreatment may be used as an additional processing step to increase the safety margin of dried vegetable products.     

常见果蔬组织破坏后Vc的损失速率试验

为研究水果、蔬菜在组织被破坏后Vc含量的变化,以脐橙、桔子、西兰花、猕猴桃、青枣等水果、蔬菜为对象,比照国家标准GB/T 6195—1986,分别对加入草酸或蒸馏水作为浸提剂所制得的两种果浆的Vc损失速率变化情况进行了研究。提出一个应用拟合和求导等数学方法建立函数,对果蔬组织被破坏后Vc的损失速率进行研究的方法。结果表明,在正常条件下,大多果蔬组织被破坏后Vc损失速率较大,故按GB/T 6195—1986测量果蔬中Vc含量时应及时检测,否则会影响检测结果。     

Classification of vegetable oils by high-resolution <Superscript>13</Superscript>C NMR spectroscopy using chromatographically obtained oil fractions

¹³C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed, soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils.     

Start-up and Operation of Laboratory-Scale Thermophilic Upflow Anaerobic Sludge Blanket Reactors Treating Vegetable Processing Wastewaters

Thermophilic anaerobic treatment of hot vegetable processing wastewaters was studied in laboratory-scale UASB reactors at 55°C. The high-strength wastewater streams, deriving from steam peeling and blanching of carrot, potato and swede were used. The reactors were inoculated with mesophilic granular sludge. Stable thermophilic methanogenesis with about 60% COD removal was reached within 28 days. During the 134 day study period the loading rate was increased up to 24 kg COD m⁻³ day⁻¹. High treatment efficiency of more than 90% COD removal and concomitant methane production of 7·3 m³ CH₄ m⁻³ day⁻¹ were achieved. The anaerobic process performance was not affected by the changes in the wastewater due to the different processed vegetables. The results demonstrated the feasibility of thermophilic anaerobic treatment of vegetable processing wastewaters in UASB reactors. © 1997 SCI.     

水果蔬菜中农药的附着系数及其应用初探

提出了附着系数这一概念,即单位质量水果蔬菜上所能附着的最大药液体积。对12种水果和19种蔬菜中农药的附着系数进行测量计算。结果表明:水果、蔬菜的农药附着系数分别为0.0037～0.044mL/g和0.0045～0.22mL/g,附着系数越大,该品种的农残风险越大。以附着系数的大小划分了果蔬品种可能的农残风险等级,对于水果,附着系数小于0.01mL/g的风险相对较低,大于0.01mL/g的风险相对较高;对于蔬菜,附着系数小于0.1mL/g的风险较低,大于0.1mL/g风险较高。利用附着系数还可计算果蔬的农药残留量,为获得农药残留量提供了一种新的方法。     

微波消解ICP-AES法评估蔬菜重金属污染情况

采用微波消解法对惠州市五个县区采集的71个蔬菜样品进行前处理,用ICP-AES测定蔬菜中As、Cd、Cr、Cu、Ni、Pb、Zn等7种元素含量,并对五个县区蔬菜重金属污染情况进行统计分析。结果表明:五县区蔬菜主要受Cd和Zn的污染,As、Cr、Cu、Ni、Pb等含量均未超过国家限量标准,叶菜类蔬菜重金属含量相对较高,瓜果类及卷心类蔬菜重金属含量比较低。     

Fruits and vegetables consumption among Costa Rican adolescents

Scientific evidence indicates that lower levels of fruit and vegetables consumption are associated with an increased risk of developing cancer and cardiovascular disease. Therefore, an increase of these foods' consumption may substantially improve public health. The purpose of this study was to examine the consumption of fruits and vegetables in 214 urban and rural adolescents in relation to the 5-A-DAY recommendation. Mean daily servings of fruits (1.7 servings) were not far from the minimum recommendation of 2 daily fruit servings. This mean decreased to 1.21 servings when banana was not counted. Mean vegetable intake (1.1 servings, including legumes) was well below the minimum recommendation of 3 vegetable servings per day. Urban adolescents and females consumed significantly (p = 0.000) fewer fruits and vegetables servings than did rural youngsters and males. However when pulses were not counted the mean daily servings of vegetables were higher in urban adolescents (p = 0.029). Only 16 from 214 adolescents (6%) consumed five or more servings of fruits and vegetables per day. This proportion decreased dramatically to 2% (p = 0.000) when pulses and banana were not counted. Examination of the factors associated with low intake of fruit and vegetables could be beneficial to develop effective interventions targeted to increase their consumption among adolescents.     

Thermal Dehydration Methods for Fruits and Vegetables

Abstract

This paper presents the results of laboratory thermal drying of some vegetables and fruits including konjak, hawthorn, apple, vegetable seeds, garlic slices, bullion vegetable, and jujube. Different materials require different drying equipment and operating conditions as discussed in this article. The results are believed to be helpful for the selection and design of industrial dryers and the choice of appropriate operating conditions in processing these and similar materials.     

Plant-Growth-Promoting Rhizobacteria Emerging as an Effective Bioinoculant to Improve the Growth,Production, and Stress Tolerance of Vegetable Crops

Vegetable cultivation is a promising economic activity, and vegetable consumption is important for human health due to the high nutritional content of vegetables. Vegetables are rich in vitamins, minerals, dietary fiber, and several phytochemical compounds. However, the production of vegetables is insufficient to meet the demand of the ever-increasing population. Plant-growth-promoting rhizobacteria (PGPR) facilitate the growth and production of vegetable crops by acquiring nutrients, producing phytohormones, and protecting them from various detrimental effects. In this review, we highlight well-developed and cutting-edge findings focusing on the role of a PGPR-based bioinoculant formulation in enhancing vegetable crop production. We also discuss the role of PGPR in promoting vegetable crop growth and resisting the adverse effects arising from various abiotic (drought, salinity, heat, heavy metals) and biotic (fungi, bacteria, nematodes, and insect pests) stresses.     

Spanish Ketogenic Mediterranean diet: a healthy cardiovascular diet for weight loss

Background

Self-reports of dietary intake in the context of nutrition intervention research can be biased by the tendency of respondents to answer consistent with expected norms (social approval bias). The objective of this study was to assess the potential influence of social approval bias on self-reports of fruit and vegetable intake obtained using both food frequency questionnaire (FFQ) and 24-hour recall methods.

Methods

A randomized blinded trial compared reported fruit and vegetable intake among subjects exposed to a potentially biasing prompt to that from control subjects. Subjects included 163 women residing in Colorado between 35 and 65 years of age who were randomly selected and recruited by telephone to complete what they were told would be a future telephone survey about health. Randomly half of the subjects then received a letter prior to the interview describing this as a study of fruit and vegetable intake. The letter included a brief statement of the benefits of fruits and vegetables, a 5-A-Day sticker, and a 5-a-Day refrigerator magnet. The remainder received the same letter, but describing the study purpose only as a more general nutrition survey, with neither the fruit and vegetable message nor the 5-A-Day materials. Subjects were then interviewed on the telephone within 10 days following the letters using an eight-item FFQ and a limited 24-hour recall to estimate fruit and vegetable intake. All interviewers were blinded to the treatment condition.

Results

By the FFQ method, subjects who viewed the potentially biasing prompts reported consuming more fruits and vegetables than did control subjects (5.2 vs. 3.7 servings per day, p < 0.001). By the 24-hour recall method, 61% of the intervention group but only 32% of the control reported eating fruits and vegetables on 3 or more occasions the prior day (p = 0.002). These associations were independent of age, race/ethnicity, education level, self-perceived health status, and time since last medical check-up.

Conclusion

Self-reports of fruit and vegetable intake using either a food frequency questionnaire or a limited 24-hour recall are both susceptible to substantial social approval bias. Valid assessments of intervention effects in nutritional intervention trials may require objective measures of dietary change.     

Trends in Development of Dried Vegetable Products as Snacks

Diverse types of vegetable snacks made using different drying methods are becoming increasingly commercially important for the food processing industry worldwide because they are also recognized as healthy for human consumption. Here we consider four aspects of drying snacks: unit operations currently used in the industry, novel or emerging methods with nontraditional means, combined (or hybrid) drying methods, and the quality changes during storage. Each drying method has its own advantages and limitations. Hybrid drying techniques are being developed to maximize the benefits of different drying techniques to produce better quality vegetable snacks that are attractive to the consumer. The merits and limitations of more than 10 drying techniques used for making dried vegetable snacks are discussed. Moreover, several new vegetables snacks dried using new drying methods are presented and discussed. A comprehensive review of the recent progress in production of dried vegetable snacks is presented and recommendations are made for future research.     

食品和农产品干燥的一种有效方法-红外加热法

农业和食品行业需要能源高效和环境友好的干燥技术,最近红外加热干燥的应用得到广泛研究。作为现代干燥技术的另一种选择,红外干燥具有加热均匀、干燥速率高、干燥时间短、节约能源、产品品质和安全性高等引人注目的优点。研究表明。将红外方法可以减少干燥时间并且节能。与热可以对果蔬实现同步漂烫和干燥,干燥和热风干燥相结合能够有效的减少干燥时间。所开发的红外冷冻相继干燥常规的空气干燥或冷冻干燥相比,更适合于生产高品质的酥脆果蔬片。红外加对稻谷进行同步干燥和杀虫。本文将综述红外加热技术的最新研究和进展。     

Solvent extraction of fatty acids from natural oils with liquid water at elevated temperatures and pressures

The use of liquid water at elevated temperatures and pressures as an extractive solvent for separating mixtures of compounds which occur in natural oils has been studied. A southern pine tall oil and a distillate from the deodorization of soybean oil were extracted with liquid water at temperatures from 298 to 312°C and pressures between 103 and 121 bar. Results indicate that water can be used to extract fatty and resin acids from crude tall oil to obtain a product with a high acid content that produces less pitch during distillation. The process can also be used to extract fatty acids from vegetable oil deodorizer distillate.