Effect of Temperature on Salt Diffusion into Vegetable Tissue

The diffusion process has many applications in food processing operations, such as extraction; preservation (curing, salting, and smoking); drying; and color transfer. Our main objective was to measure the diffusion coefficient, D_s, of salt into vegetable tissue (celery, mushroom, and water chestnut) as a function of temperature. For this purpose, a sample of tissue was used to separate donor and receiver compartments, each with solutions of different salt concentrations. Values of D_s were determined by periodic monitoring. The results show that the equilibrium distribution coefficient, K, and D_s of all materials were significantly affected by temperature (p < 0.05). The temperature dependence of D_s for all three materials was described by the Arrhenius equation, with water chestnut showing the lowest activation energy.     

Prevalence of parasitic contamination in vegetables used for raw consumption in Shahrekord, Iran: Influence of season and washing procedure

This study aimed to determine the prevalence of intestinal parasites in raw vegetables consumed in Shahrekord, Iran; and efficacy of season and washing procedures to remove parasites from the vegetables. A total of 304 field vegetable samples composed of parsley, spearmint, scallion, basil, coriander, dill, cress, leek, tarragon, radish and purslane were purchased from the vegetable markets. Each sample was divided into three groups. One group was used as the unwashed sample and the second and third groups were washed with traditional and standard washing procedures, respectively. Intestinal parasites were detected in 32.6% of unwashed, 1.3% of traditionally washed and not in any standard washed samples (P < 0.001). The parasites were detected in unwashed vegetable samples included Ascaris lumbricoides eggs (14.1%), Taeniid spp. eggs (9.2%), Toxocara spp. eggs (3.3%), Trichostrongylus spp. eggs (4.3%), Giardia spp. cysts (8.2%) and non-pathogenic protozoan Entamoeba coli cysts (9.2%). The rate of parasitic contamination in different seasons was found to be 55% in spring, 45.5% in summer, 14.9% in autumn and 12.3% in winter (P < 0.005). The results highlight the potential of unwashed raw vegetables in transmission of intestinal parasites to human, and also emphasize the use of standard washing procedure (proper washing and disinfecting) before consumption of vegetables instead of traditional procedure (quick washing without disinfecting).     

Quantification of organophosphate insecticides and herbicides in vegetable samples using the “Quick Easy Cheap Effective Rugged and Safe” (QuEChERS) method and a high-performance liquid chromatography-electrospray ionisation-mass spectrometry (LC-MS/MS) technique

A Quick Easy Cheap Effective Rugged and Safe (QuEchERS) extraction was developed and followed by selective analysis using a liquid chromatography-mass spectrometry method for the quantification of eighteen pesticides in vegetable samples. This method was accurate (?99.5%), and it exhibited limits of detection and quantification values in the 0.006-0.091 and 0.020-0.314 μg kg⁻¹ ranges, respectively. Furthermore, the coefficients of variations (?0.9999) were less than 1% at the low μg kg⁻¹ end of the method. Mean recoveries ranged between 94% and 102%, and relative standard deviations were below 10%. Based on these results, the methodology was proven to be highly efficient, robust, and suitable for monitoring the maximum residue limits (MRL) compliance of a wide range of commodity/pesticide combination. This method was successfully applied to the analysis of vegetable samples that were collected from different government farmers’ markets and street shops in urban areas. The presence of target pesticides was found in the range of 0.016 and 50.85 μg kg⁻¹.     

Field Incurred Endosulfan Residues in Fresh and Processed Vegetables and Dietary Intake Assessment

Mitigation in endosulfan residues was determined in spinach, cauliflower, potato, brinjal, tomato, and okra by using different techniques. The endosulfan residues were determined in 66 samples of different vegetables, and it was found that the highest endosulfan residues (mg kg^?1) were at the raw stage in okra (1.71), brinjal (1.50), and spinach (1.16), respectively. The residue of endosulfan was lowest in potato (0.130) mg kg^?1. Washing reduced the endosulfan residue from 15 to 28%, peeling reduced it from 60 to 67%, and cooking further lowered it from 18 to 31% in all vegetables. Dietary intake assessment revealed that only samples of okra exceeded the maximum permissible intake value at the raw stage, whereas all the other samples were below maximum permissible intake value, although some were exceeding the maximum residue limits at the raw stage.     

新型保温材料在现代果蔬物流中的应用研究

通过4种不同保温材料对木耳菜和西兰花的保藏效果对比,以确定相对较好的保温材料。通过温度变化、呼吸强度、丙二醛含量、新鲜度、叶绿素含量变化指标的研究,得出表层是260g/m2PVC,里层是无纺布,中间填充胶棉240g/m2的复合材料最佳。     

A comparative study of phenolic compounds and antioxidant and antiproliferative activities in frequently consumed raw vegetables

The aim of this study was to assess the antioxidant value and antiproliferative activity of some vegetables such as raw garlic (Allium sativum L), white and yellow, and red onions (Allium cepa L), red and green peppers (Capsicum annuum L.), and white cabbage (Brassica oleracea var. capitata f. alba), which were harvested in the same year and in the same geographical and climatic conditions. It was found that the highest content of some bioactive compounds (25.19 ± 2.2 mg GAE/g, 3.84 ± 0.3 mg CE/g, 4.88 ± 0.3 mg CE/g, 59.20 ± 0.8 μg CE/g, 1992 ± 99.8 μg AA/g, 452.7 ± 26.1 mg CGE/kg DW for polyphenols, flavonoids, tannins, flavanols, ascorbic acid, and anthocyanins, respectively) and the antioxidant activity (41.32 ± 3.9, 31.05 ± 2.7, 59.17 ± 5.2 and 58.94 ± 5.1 μM TE/g for DPPH, FRAP, CUPRAC and ABTS, respectively) was in red onion. Methanol extracts in concentration of 1,000 μg ml⁻¹ of garlic and red onion exhibited antiproliferative activity (83.1 ± 2.1 and 85.0 ± 3.2% of viability, respectively). In spite of relatively high antioxidant activity in methanol extracts of yellow onion, red and green pepper, no antiproliferative activity on both tumor cell lines was registered. In conclusion, among the studied vegetables raw red onion was the preferable. The interrelationship was in the following order: red onion > white onion = yellow onion > red pepper > garlic = green pepper > white cabbage. The antiproliferative activities of these vegetables were different: some samples reacted only on Calu-6 and the others—on SNU-601. Thus, vegetables from the same cultivation place were examined for their antioxidant and antiproliferative activities with four different methods. Based on obtained data a direct comparison between these vegetables was possible for the first time.     

Evaluation of metal concentrations in edible vegetables grown in compost amended soil

Agricultural uses of compost usually have a positive effect on the yield of vegetable crops for human consumption. However, compost that contains heavy metals can transfer these components to soils and plants. To evaluate the contamination levels of metals in soil, compost, and edible vegetables, the Mn, Zn, Pb, Cd, Cu, and Ni total contents were measured. Metal availability in soils, as well as other variables – the pH, CEC (cation exchange capacity), total nitrogen, organic carbon, particle size distribution and mineralogy of the clay fraction – were examined in the soil samples. The analysed compost samples were produced from urban solid waste, cattle manure, and edible vegetable and tree pruning residues. The values of pH, CEC, total nitrogen, organic matter, exchangeable hydrogen and carboxylic groups were measured in the compost samples. Of the six metals examined in the soils, in general, Mn and Zn attained the highest concentrations, followed by Cu. Relatively high Mn, Zn, Cu, Cd and Pb concentrations were found in the soils. Metal concentrations extracted with DTPA were below the critical levels in soils, i.e. the levels above which toxicity is likely. In general, Zn, Pb, Cd, Cu and Ni concentrations in compost were lower than those reported by other workers, while Mn levels were within the range for this metal in compost. The results showed that there was an effect of the vegetable type (p < 0.01) for all the parameters examined. High Pb concentrations were found in lettuce and chive as compared with the tolerance limit for this metal in fresh vegetables in Brazil. Cadmium concentrations were also enhanced in the fresh vegetables compared with the typical concentrations of metals in plants. Zinc, Cu, Cd, and Ni concentrations were lower than the tolerance limits established for foods by the Brazilian legislation.     

Oxalate contents of species of the Polygonaceae,Amaranthaceae and Chenopodiaceae families

A high dietary oxalate intake influences mineral and trace element absorption in humans and may lead to calcium oxalate stone formation due to the ability of oxalate to form insoluble complexes with divalent cations in the gastrointestinal tract. The soluble and total oxalate contents of species in the Polygonaceae, Amaranthaceae and Chenopodiaceae families were measured using an HPLC-enzyme-reactor method. Polygonaceae, Amaranthaceae and Chenopodiaceae include most of the foods with excessively high oxalate concentrations. Amaranth is a specie of the Amaranthaceae family, Polygonaceae include buckwheat, rhubarb, and sorrel, whereas beetroot, mangold, spinach, and quinoa are species of the Chenopodiaceae family. Obviously, oxalate is accumulated in these plant families in each plant tissue, i.e., in leaves, stems, hypocotyl-root and nuts. The highest oxalate content was found in leaves and stems of plants in these families. Soluble oxalate ranged from 59 to 131 mg/100 g in roots and nuts, and from 258 to 1029 mg/100 g in leaves and stems. Total oxalate ranged from 143 to 232 mg/100 g in roots and nuts, and from 874 to 1959 mg/100 g in leaves and stems. Patients with calcium oxalate stone disease should be advised to avoid these oxalate-rich foods.     

Field incurred chlorpyrifos and 3,5,6-trichloro-2-pyridinol residues in fresh and processed vegetables

The effect of washing, peeling and cooking on residue levels of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP) in winter (spinach, cauliflower, potato) and summer vegetables (eggplant, tomato, okra) was determined. Analysis was carried out by capillary gas chromatography (DB-5MS capillary column) with mass selective detection. The samples were collected from trials conducted under controlled conditions as well as from the farmer’s field. In supervised field trials, the highest chlorpyrifos residue was found at raw stage in spinach (1.87 mg kg⁻¹) followed by okra (1.41 mg kg⁻¹) and eggplant (1.25 mg kg⁻¹). The lowest residue of chlorpyrifos was recorded in cauliflower (0.036 mg kg⁻¹). The chlorpyrifos residue reduced from 15 to 33% after washing, 65–85% post-peeling and cooking further lowered it from 12% to 48% in all the tested vegetables; while an increase in TCP concentration was observed during heat treatment. Out of 267 vegetable samples collected from the farmer’s field, 225 samples contained detectable residues representing 84% rate of contamination. About 6% of samples contained chlorpyrifos residues above maximum residue limits (MRLs). However, vegetable processing reduced the chlorpyrifos residue below the MRL.     

COMBINED INNOVATIVE HEAT PUMP DRYING TECHNOLOGIES AND NEW COLD EXTRUSION TECHNIQUES FOR PRODUCTION OF INSTANT FOODS

ABSTRACT

There is an increased demand for convenient foods including ready-to-eat and instant products. These products are desired with minimum concentration of synthetic chemicals. This creates challenges for the food industry and dryers manufactures to develop new technologies to process difficult-sensitive materials and to supply final products with high quality and improved properties. Fruits and vegetables are mainly composed of water, carbohydrates, proteins and lipids. Due to modification of chemical and physical bonds the compounds the material becomes viscous and sticky during processing. Conventional dryers have limitations in handling such sensitive materials. Heat pump dryers have been applied in the production of a diversity of ready-to-eat foods and dried instant products for the last five years at SINTEF-NTNU. Besides being energetically efficient and environmentally friendly, the heat pump drying technology provides a wide range of drying conditions as required to produce powders with improved characteristics. This work describes the new technologies and processing line for the production of instant foods as well as the measurements on the properties and quality attributes for raw, intermediate and final instant products.