The availability of soluble oxalates in stir‐fried silver beet (Beta vulgaris var. cicla) leaves eaten with yoghurt

Silver beet (Beta vulgaris var. cicla) leaves contain oxalates, and the addition of yoghurt, a food rich in calcium, to stir‐fried leaves was investigated as a way of reducing the soluble oxalate content. Fourteen participants ingested 115 g stir‐fried silver beet leaves with or without standard yoghurt and low‐fat yoghurt, respectively. Stir‐fried silver beet leaves contained 209.1 ± 0.1 mg of total oxalates per meal fresh weight (FW) and 109.2 ± 0.1 mg of soluble oxalates per meal FW. The proportion of soluble oxalates was reduced from 52% to a mean of 30% of the total oxalates when standard yoghurt or low‐fat yoghurt was added. The mean absorption of oxalate was determined by measuring the output of oxalate in the urine over a 6‐h period following ingestion of the meals. The mean absorption of oxalate from stir‐fried silver beet leaves was 2.41%, which reduced to 1.10% and 0.89% when consumed with standard yoghurt and low‐fat yoghurt, respectively.     

Total and soluble oxalate content in legume vegetables used in the preparation of frozen products for consumption

The aim of the investigation was to compare oxalate retention in two types of frozen product prepared for consumption after frozen storage: one obtained using the traditional method (blanching‐freezing‐frozen storage‐cooking) and a convenience food involving cooking‐freezing‐frozen storage‐defrosting and heating in microwave oven. The investigation included three species of legume vegetables: immature (wax‐stage maturity) seeds of broad bean and green pea, and French bean. Fresh broad bean seeds contained 53 mg total oxalates in 100 g fresh matter; pea 38 mg; and French bean 88 mg. Soluble oxalates comprised 53, 58 and 72% of total oxalates. The treatments applied resulted in reduction of the level of total and soluble oxalates, and oxalate to calcium ratio (broad bean and French bean); there was no influence on the level of calcium bound as calcium oxalate; true retention of oxalates was lower than apparent retention (green pea and French bean).     

Oxalate content of some leafy vegetables and dry legumes consumed widely in Egypt

Oxalic acid and total oxalate contents were determined in four leafy vegetables and six dry legumes consumed widely in Egypt. The four vegetables, normally eaten raw, can be arranged according to their oxalate content, in descending order, as follows: green onion (leaves), green onion (bulbs), leek, radish (leaves), radish (roots) and roquette. Oxalic acid represented 76–86% of the total oxalates.Dry faba beans had the highest oxalic acid content, followed, in descending order, by fenugreek, lentils, peas, chickpeas and lupin. The ratio of oxalic acid to total oxalates differs according to the total oxalate content of the legume variety. Decortication, steeping, sprouting, stewing, boiling and baking reduced the oxalate content of seeds in different ways. Sprouting and steeping, followed by decortication, resulted in the most pronounced decrease in oxalates, especially in faba beans and lupin.     

Composition and bioavailability of oxalates in baked taro (Colocasia esculenta var. Schott) leaves eaten with cows milk and cows milk and coconut milk

Taro leaves are an important food in the Pacific Islands but the overall oxalate composition and its nutritional effect has not been investigated. The oxalate contents of taro leaves were determined using chemical and in vitro extraction methods. Maori‐type taro leaves contained 524.2 ± 21.3 mg total oxalates 100 g^?1 fresh weight (FW) and 241.1 ± 20.9 mg soluble oxalates 100 g^?1 FW while the Japanese‐type leaves contained 525.6 ± 19.9 mg total oxalates 100 g^?1 FW and 330.4 ± 28.3 mg soluble oxalates 100 g^?1 FW. Maori‐type taro leaves contained 416.4 ± 1.5 mg gastric soluble oxalates 100 g^?1 FW and 212.4 ± 34.8 mg intestinal soluble oxalates 100 g^?1 FW while the Japanese‐type leaves contained 433.3 ± 9.7 mg gastric soluble oxalates 100 g^?1 FW and 224.2 ± 38.7 mg intestinal soluble oxalates 100 g^?1 FW). Human feeding experiments were conducted to determine the availability of the oxalates in the baked leaves following additions of cows milk and coconut milk. The consumption of a test meal of baked taro leaves resulted in a significant increase (P < 0.001) in the output of urinary oxalate in the following 6 h when compared to the output of oxalate during a reference collection. When the leaves were baked with cows milk or cows milk and coconut milk combined and consumed there was a small non‐significant reduction in urinary oxalate output which suggests that less soluble oxalate was absorbed from these mixtures.     

Determination of oxalates in Japanese taro corms using an in vitro digestion assay

An in vitro assay was used to extract gastric soluble and intestinal soluble oxalates from the corms of four different Japanese taro (Colocasia esculenta (L.) var. Schott) cultivars (Akame, Ishikawa-wase, Yamato-wase and an unnamed cultivar). The oxalate contents were measured in the raw tissue and after boiling and baking the corms.     

NUTRIENT QUALITY OF SELECTED VEGETABLES PREPARED BY CONVENTIONAL AND COOK-FREEZE METHODS

Selected vegetables (spinach, broccoli, sweet potatoes, and collard greens) prepared in 2.27 kg (5 lb) quantities by boiling, were frozen and stored for six months at ?18°C. Zinc, iron, β-carotene, and ascorbic acid were determined on the raw vegetable immediately after cooking and after reheating in a microwave oven subsequent to 6 months frozen storage. The greatest nutrient loss occurred for water soluble nutrients during boiling. Nutrient comparison between cooked samples (conventional method) and samples microwaved after 6 months frozen storage (cook-freeze method) indicated that differences existed only in ascorbic acid content of spinach. Data indicated that vegetables prepared by cook-freeze, a method used by health care institutions, were generally equal in nutrient quality to conventionally prepared vegetables.     

Effect of different cooking methods on the content of vitamins and true retention in selected vegetables

This study evaluated the effect of different cooking methods including blanching, boiling, microwaving and steaming on the content of vitamins in vegetables. True retention was estimated using the yield expressed as a ratio of the weight of the cooked sample to the weight of the raw sample. The retention of vitamin C ranged from 0.0 to 91.1% for all cooked samples. Generally, higher retention of vitamin C was observed after microwaving with the lowest retention recorded after boiling. Cooked vegetables were occasionally higher contents of fat-soluble vitamins, including α-tocopherol and β-carotene, than that of their fresh counterparts, but it depends on the type of vegetables. Microwave cooking caused the greatest loss of vitamin K in crown daisy and mallow; in contrast, it caused the least loss of vitamin K in spinach and chard. Cooking may cause changes to the contents of vitamins, but it depends on vegetables and cooking processes.     

The antioxidant capacity and polyphenol content of organic and conventional retail vegetables after domestic cooking

Vegetable consumption is associated with health benefits. Organic foods are thought to have higher contents of antioxidant substances. The objective of this work is to quantify soluble and hydrolyzable polyphenols, ascorbic acid, and the antioxidant capacity of fresh conventional and organic retail vegetables (potato, carrot, onion, broccoli, and white cabbage) while evaluating the effect of boiling, microwaving, and steaming on these parameters. The recovery rate for soluble and hydrolyzable polyphenols was variable according to the vegetable analyzed. However, soluble polyphenols resulted in lower recovery rates than did hydrolyzable phenolics after cooking. Organic vegetables showed higher sensitivity to heat processing than did conventionally grown vegetables. In general, cooking was found to lead to reductions in the antioxidant capacity for most vegetables, with small differences between the cooking methods applied. Even with the alterations in their content, polyphenols showed a positive correlation with antioxidant capacity in raw and cooked vegetables from both types of agriculture.     

Chemical composition and in vitro starch bioavailability of Phaseolus vulgaris (L) cv Mayocoba

Common beans of the Mayocoba variety were cooked (178 min) and evaluated regarding their chemical composition and starch digestibility in vitro. Mean physical characteristics of the Mayocoba grain were: thousand‐kernel weight, 443.0 (±0.98)g; length, 12.45 mm; width 7.84 mm and thickness, 6.44 mm. Total starch content in Mayocoba bean was 40.24% (dmb). The available starch was 22.87%, whereas resistant starch accounted for 6.4% and retrograded resistant starch represented 3.3% of the cooked seed weight. None of these values changed with storage time. The Mayocoba variety presented values of soluble indigestible fraction of approximately 8.0% and insoluble indigestible fraction of 36%, which did not change with storage. Both simple enzymatic hydrolysis rate and hydrolysis index (HI = 36%) indicated a slow hydrolysis of Mayocoba starch. HI‐based predicted glycemic index was 39%, all of which suggested a ‘slow carbohydrate’ feature for this bean. Copyright © 2004 Society of Chemical Industry     

Vitamin C losses in some frozen vegetables due to various cooking methods

Frozen spinach, peas, green beans and okra were commercially cooked in three different stewpans (double based stainless steel, teflon, pyrex) with and without thawing. The vitamin C levels were effected both by cooking methods and stewpans. Frozen peas were found to be the least (3.5% loss), and frozen green beans were found to be the most (19.6% loss) effected vegetables by thawing. In all of the stewpans, double based stainless steel pan retained more vitamin C than the others. While boiling spinach, peas, green beans, and okra without thawing resulted 46.5, 25.2, 18.2, and 21.6% vitamin C loss in double based stainless steel pan, boiling them in pyrex pan resulted 58.5, 36.0, 42.1, and 28.2% vitamin C loss, respectively. Besides, the losses in cooking processes were accelerated in thawed vegetables with the same tendency; that is more destruction occurred in samples boiled in pyrex pan (60.3% loss in spinach, 40.8% loss in peas, 48.4% loss in green beans, and 41.6% loss in okra). According to the results, it was found that thawing before cooking is useless and causes more vitamin C loss. Therefore, frozen vegetables must not be thawed before cooking. In order to prevent vitamin C from destruction, using double based stainless steel pan, minimum amount of water and cooking of frozen vegetables are recommended.     

Hypolipidemic and hypoglycemic potential of raw,boiled, and sprouted mung beans (Vigna radiata L. Wilczek) in rats

This study was carried out to investigate the hypolipidemic and hypoglycemic potential of raw, boiled, and sprouted mung beans in rats. Oven dried mung bean powders; raw, sprouted, and boiled were included at 30% level in the diet of seven weeks old male Wistar rats maintained for 5 weeks on high (0.5%) cholesterol diet in comparison with control diet. Low serum glucose and triglyceride concentrations (p < .05) in raw and processed mung bean diets fed rats were supported by low serum insulin level in both raw mung bean diet and boiled mung bean diet fed rats. Hypoglycemic effect in sprouted mung bean fed rats was supported by higher α‐amylase inhibitory activity and α‐glucosidase inhibitory activity of sprouted mung beans. Increase in serum non‐HDL cholesterol concentration and decrease in HDL cholesterol concentration caused by high cholesterol diet were modulated (p < .05) by both boiled and sprouted mung bean diets.

Practical applications

Mung bean is a green legume rich in protein, fiber, antioxidants, and phytonutrients. Hypocholesterolemic and hypoglycemic potential of raw mung beans have been shown previously. It is well known that cooking and processing modulate nutritional and biochemical parameters of foods. However, very limited information is available on the effect of processing on functional properties of legumes. Results of this study showed that boiling and sprouting improved the soluble fiber content and hypocholesterolemic potential of mung beans. Thus, the processed mung beans may be more suitable for developing food supplements for patients with hypercholesterolemia.     

Physicochemical and Sensory Properties of Dehydrated Bean Paste Products as Related to Bean Varieties

The objective was to compare physicochemical properties of bean paste products from six bean varieties to determine whether there were significant differences in the resulting product. Crude protein in the dried bean pastes ranged from 23% to 29% and ash 1.1% to 1.8%. Fiber ranged from 16% to 6.3% soluble. 10.6% to 22.7% insoluble. and 12.3% to 28.3% total dietary fiber. Nonstarch polysaccharide contents varied from 12% to 32%. Only 7.5% to 13.8% of total raflinose and stachyose were retained in the paste products. Trypsin inhibitor activity in the bean pastes was 1% to 2% of that detected in raw beans. Mung bean paste had lowest overall sensory quality. Navy and pinto bean pastes had good smoothness, aroma, and acceptance and could be used as substitutes for preparing traditional bean paste products.     

广东部分地区食品中环己基氨基磺酸钠的含量调查

目的了解广东部分地区食品中环己基氨基磺酸钠添加情况。方法采用气相色谱法对458个随机在大型商场和小型超市售卖的包装食品进行环己基氨基磺酸钠含量的检测。结果本次测试共458个,14大类食品,其中19.2%食品添加了环己基氨基磺酸钠,且大部分食品中的添加量在GB 2760—2014《食品安全国家标准食品添加剂使用标准》内,属于可放心食用的食品,不过其中有2.8%的食品超出了标准范围。14大类中饮料类、腌渍的蔬菜、脱壳熟制坚果与籽类、熟制豆类、凉果类、冷冻饮品、果冻糕点、复合调味料、腐乳、带壳熟制坚果与籽类、饼干类食品的风险较低,方便食品(调味面制品)、蜜饯凉果食品的风险较高。结论食品监管部门仍需要继续保持在食品生产消费中对环己基磺胺酸钠的安全风险管理。     

The effect of cooking on Brassica vegetables

Assessing antioxidant intake requires a food antioxidant database. However, cooking may affect antioxidant content due to antioxidant release, destruction or creation of redox-active metabolites. Here, effects of boiling, steaming and microwaving of broccoli, cauliflower, cabbage and choy-sum (Chinese cabbage) were explored by measuring antioxidant contents of raw and cooked vegetables. Cooking water was also tested. For all cooked vegetables, antioxidant content was highest in steamed > boiled > microwaved, and decreased with longer cooking time, regardless of method. All steamed vegetables had higher antioxidant contents than had matching raw vegetables. Effects were variable for boiling and microwaving. Microwaving caused greater antioxidant loss into cooking water than did boiling. Marked losses of anitoxidants occurred in microwaved cabbage and spinach. To assess food antioxidant content/intake accurately, cooking effects need detailed study. Steaming may be the cooking method of choice to release/conserve antioxidants. The cooking water is a potentially rich source of dietary antioxidants.     

The comparative evaluation of the nutrient composition and sensory attributes of four vegetables cooked by different methods

The following four vegetables; beans (Phaseolus vulgaris var. vulgaris), brinjal (Solanum melongena var. esculentum), knol‐khol (Brassica oleracea var. caulorapa) and radish (Raphanus raphanistrum satvius) were processed either by conventional, pressure or microwave cooking methods and were analysed for their nutritional and sensory profile. Raw samples were used as controls. Microwave cooking resulted in greater moisture loss when compared with vegetables cooked by other methods. The protein, fat, total ash, calcium, phosphorus, iron, and dietary fibre contents of the vegetables did not differ significantly in raw or cooked vegetables. Ascorbic acid was destroyed to the greatest extent by pressure cooking followed by microwave and conventional method. The sensory attributes of cooked vegetables, as evaluated by a paired preference test, revealed that there were no significant differences between cooked radish and knol‐khol but, in the case of beans and brinjal, microwave and conventionally cooked samples were preferred over pressure cooked ones.     

Processing and fermentation of the african locust bean (Parkia filicoidea Welw.) to produce dawadawa

African locust beans (Parkia filicoidea Welw.) were processed and fermented to the traditional West African condiment dawadawa. The beans were transformed to ‘processed substrate’ by boiling and dehulling, and then fermented at 37°C in static fermenter units. The overall mass balance and the mass balances of several bean components (moisture, fat, protein, ash and carbohydrate) were studied. It was found that 1.0 kg of raw beans (6.4% moisture) yielded 1.3 kg of processed substrate (63% moisture) which in turn was converted to 1.2 kg of dawadawa (65% moisture). The loss of bean solids during processing was due to the removal of adhering pulp and testa as well as to solids extraction during boiling and washing. Overall, 57% of the bean dry weight, 85% of the carbohydrate, 48% of the ash, 40% of the protein and 1% of the fat were lost in the conversion of raw beans to dawadawa. The dawadawa had considerably higher fat and protein contents than the raw beans and was a pleasant tasting food whereas the raw beans were inedible. Some microbiological aspects of the fermentation were also investigated. Normally prepared fermentation substrate was compared with both sterilised and radappertised beans in terms of conversion to dawadawa, number of colony forming units present, and the development of pH and titratable acidity. The presence of microorganisms was found to be obligatory for the conversion to proceed. Simultaneous increases in both pH and titratable acidity were observed during the fermentation.     

Nitrate and nitrite content in organically cultivated vegetables

The nitrate and nitrite content of leaf vegetables (Swiss chard, sea beet, spinach and cabbage), “inflorescence” vegetables (cauliflower) and fruit vegetables (eggplant and vegetable marrow) grown with organic fertilizers have been determined by a modified cadmium–Griess method. Samples were purchased from organic food stores as well as collected directly from an organic farm in Madrid (Spain). Nitrate levels were much higher in the leaf vegetables (especially Swiss chard species; average over the different samples and species of 2778.6 ± 1474.7 mg kg^{? 1}) than in inflorescence or fruit products (mean values between 50.2 ± 52.6 and 183.9 ± 233.6 mg kg^{? 1}). Following Swiss chard species, spinach (1349.8 ± 1045.5 mg kg^{? 1}) showed the highest nitrate content, and nitrite was found above the limit of detection in some samples only (spinach, 4.6 ± 1.0 mg kg^{? 1}; sea beet, 4.2 ± 0.7 mg kg^{? 1} and Swiss chard, 1.2 ± 0.4 mg kg^{? 1}). Some vegetables (spinach, cabbage and eggplant) had lower nitrate content in the samples harvested in summer, showing the influence of climatic conditions on the nitrate levels in a plant. The samples taken directly from the organic farm, with the exception of eggplant, had higher or slightly higher average nitrate values than samples purchased in the organic food stores, ranging from 117 to 1077%.     

不同加工工艺的青豆粉营养品质及风味变化分析

与鲜青豆进行比较,研究煮制青豆、烤制青豆、冻干青豆对青豆粉的基本成分、抗氧化性能和香气成分的影响。结果表明：不同加工工艺的青豆粉的淀粉、粗蛋白、总黄酮和总酚含量差异显著（p<0.05）,冷冻干燥青豆粉中总黄酮和总酚含量分别为0.40 g/g和0.96 mg/g;煮制青豆中总黄酮和总酚含量分别为0.30 g/g和0.71 mg/g;冷冻干燥、煮制后的青豆所得青豆粉的自由基清除力、还原力能力较高,而炒制所得青豆粉的抗氧化能力最低。运用固相微萃取-气相色谱-质谱联用对鲜青豆和3种加工工艺的青豆粉的香气物质进行分析,鲜青豆、煮制后热风干燥的青豆粉、烤制干燥青豆粉和冷冻干燥青豆粉各自鉴定出17、20、41种和21种挥发性香气成分。综合分析,冷冻干燥和煮制后干燥的青豆粉抗氧化能力较高,能够较好的保存青豆的营养价值,对于青豆的香气也有较好的保留和增加。众所周知冷冻干燥会能耗较大,因此,可选择煮制后热风干燥制作青豆粉。     

High Performance Liquid Chromatographic Determination of Carbohydrates in Raw and Cooked Vegetables

The soluble sugar contents of 17 raw and cooked vegetables were determined by TLC and HPLC. In general, the soluble carbohydrate content of vegetables is low. For raw materials the highest content was found in carrot, red cabbage, egg plant, green bean and leek. Upon cooking the glucose, fructose and total sugar contents decrease and this diminution is more drastic in the case of frying. The amount of sucrose, except in the case of carrot, egg plant and green bean, increases with cooking. The maltose content of the broad bean increases in the culinary process.     

Effect of different technological and culinary treatments on iron retention,nutritional density and recommended dietary intake in fourteen vegetable species

The present work determined iron content in fourteen species of vegetable prepared for consumption. The experimental material consisted of raw and boiled raw vegetables and two types of frozen product: one traditionally produced (blanching before freezing); the other obtained using the modified method (boiling before freezing), having the characteristics of a ready‐to‐eat convenience product. Nutrient density (ND) and recommended dietary intake (RDI) were established on the basis of iron content. The highest iron content was found in pea seeds (2.03 mg per 100 g fresh weight) and the lowest in root vegetables (0.38–0.60 mg). Iron retention was similar in all pea, broad bean, New Zealand spinach, kale, white cauliflower, celery and red beet products. In the remaining products, the significantly lowest retention was found in the traditionally frozen product (Sample C) and the highest in the ‘convenience’ frozen product (Sample D). The above‐mentioned order also applied to ND and RDI values. Only in the ND of parsnip calculated for women did any value fall below 100%.