Soluble and insoluble fiber contents of some Cameroonian foodstuffs

As a result of the lack of reliable data on the fiber content of African foodstuffs, a study to determine the dietary fiber contents (soluble, insoluble and total) on a dry weight basis of a selected variety of major Cameroonian foods was conducted. The influence of processing and preparation methods on the fiber content was also assessed. Vegetables were found to be the richest source of total dietary fiber (57%), followed by legumes and seeds (30%) and fruits (16.5%). Okro (Hibiscus esculenta), plantain (Musa paradisiaca) and beans (Phaseolus spp) showed varietal differences in their soluble and insoluble fiber content, while methods of processing and preparation significantly influenced the fiber content of cassava (Manihot esculenta), corn (Zea mays) and beans.     

The contribution of different groups of foodstuffs to the intake of dietary fibre

The intake of Dietary Fibre (which is defined as the sum of lignin and the polysaccharides not hydrolysed by the endogenous secretions of the human digestive tract) is derived from the plant cell walls in the diet and other non-structural polysaccharides either present naturally in foods, or derived from polysaccharide food additives such as gums or algal polysaccharides. The composition of this complex mixture, its chemical and physical properties, and therefore, the physiological effects associated with its ingestion, will vary according to the foods making up in the diet. While techniques for the measurement and characterisation of dietary fibre still call for a considerable amount of methodological development it is possible to obtain reliable estimates for the major components and the overall composition of these components. These show that in fruits and vegetables the total dietary fibre content (on a fresh weight basis) lies between 2 and 5 g/100 g with peas and beans being an exception in having higher contents. The dietary fibre in cereals varies with the cereal and the reate of extraction used; for example, wholemeal wheat flours contain between 12 and 15 g/100 g whereas white wheat flour (72% extraction) contains between 3 and 4 g/100 g. Wheat bran and related products have much higher contents. The proportion of the dietary fibre present as cellulose does not show great variablility but lignin is extremely variable. Fruits and vegetables contain very small amounts of lignin unless they have lignified seeds or special lignified tissues. The non-cellulosic polysaccharides of fruits and vegetables are characteristically rich in uronic acids (from pectic substances) and arabino-galactans. In cereals β-glucans and arabino-xylans predominate and wheat bran and wholemeal wheat and rye flours are particularly rich in arabino-xylans. The amounds and composition of the dietary fibre in foods commonly forming the diet eaten in the United Kingdom will be reviewed and their contribution to the diet as a whole will be discussed. Changes in the pattern of food consumption in the United Kingdom in the past century will be discussed in relation to the effects that these have had on the consumption of dietary fibre.     

Resistant starch content of Indian foods

Resistant starch (RS) was determined in a few selected cereals, legumes and vegetables after processing. Higher RS contents were observed in foods subjected to dry heat treatment compared to wet processed ones. Among the foods studied, sorghum, green gram dhal, and green plantain showed relatively higher RS content. Based on the RS content thus determined in individual foods and the known composition of the Indian diet, RS content of Indian diets were computed.     

Health effects of wheat lectins: A review

Lectins are carbohydrate-binding proteins present in most plants. They play a role in protecting plants against external pathogens, like fungi, and other organisms. Some common dietary staples, such as cereal grains and legumes, have relatively high concentrations of a variety of lectins. A part of the proteins present in wheat germ is characterized as wheat germ agglutinin (WGA), in this respect. Authors of popular nutritional plans propose adverse health effects of this wheat lectin. With the use of different arguments, the consumption of foods high in lectins is discouraged. In this context, we discuss the effects of lectins from wheat on human health. Up-to-date research findings on mechanisms that wheat lectins have effects on health factors, such as obesity, autoimmune disease, and celiac disease, are critically reviewed. We conclude that there are many unsubstantiated assumptions made. Current data about health effects of dietary lectins, as consumed in cooked, baked, or extruded foods do not support negative health effects in humans. In contrast, consumption of WGA containing foods, such as cereals and whole grain products, has been shown to be associated with significantly reduced risks of type 2 diabetes, cardiovascular disease, some types of cancer, as well as a more favourable long-term weight management. Research is recommended to define actual active lectin contents in wheat-based foods after heat preparation for human consumption.     

Effect of a natural high fibre diet on blood lipids and intestinal transit time in man

In two experiments with young healthy volunteers the effects of a high in take of dietary fibre on blood lipids and intestinal transit time were investigated. In the first experiment the effects were studied of a high-fibre diet, in which half of the dietary fibre was provided by vegetables and fruits and the rest came from bread and other cereal products. In the second trial the effects of dietary fibre derived from vegetables and fruits were compared with those of isolated citrus pectin and wheat bran. It is concluded that—at least in short-term controlled experiments—fibre-rich food-stuffs have only a small (vegetables and fruits) or no (bran) favourable effect on the level of serum cholesterol. However, in uncontrolled circumstances, a ‘natural’ high fibre diet may through its low fat and cholesterol content indirectly reduce the concentration of serum cholesterol. A high-fibre diet with vegetables and fruits as well as a diet with bran shorten the intestinal transit time and enhance faeces production.     

Sorghum and millet phenols and antioxidants

Sorghum is a good source of phenolic compounds with a variety of genetically dependent types and levels including phenolic acids, flavonoids, and condensed tannins. Most sorghums do not contain condensed tannins, but all contain phenolic acids. Pigmented sorghums contain unique anthocyanins that could be potential food colorants. Some sorghums have a prominent pigmented testa that contains condensed tannins composed of flavan-3-ols with variable length. Flavan-3-ols of up to 8–10 units have been separated and quantitatively analyzed. These tannin sorghums are excellent antioxidants, which slow hydrolysis in foods, produce naturally dark-colored products and increase the dietary fiber levels of food products. Sorghums have high concentration of 3-deoxyanthocyanins (i.e. luteolinidin and apigenidin) that give stable pigments at high pH. Pigmented and tannin sorghum varieties have high antioxidant levels that are comparable to fruits and vegetables. Finger millet has tannins in some varieties that contain a red testa. There are limited data on the phenolic compounds in millets; only phenolic acids and flavones have been identified.     

Sorghum and millet phenols and antioxidants

Sorghum is a good source of phenolic compounds with a variety of genetically dependent types and levels including phenolic acids, flavonoids, and condensed tannins. Most sorghums do not contain condensed tannins, but all contain phenolic acids. Pigmented sorghums contain unique anthocyanins that could be potential food colorants. Some sorghums have a prominent pigmented testa that contains condensed tannins composed of flavan-3-ols with variable length. Flavan-3-ols of up to 8–10 units have been separated and quantitatively analyzed. These tannin sorghums are excellent antioxidants, which slow hydrolysis in foods, produce naturally dark-colored products and increase the dietary fiber levels of food products. Sorghums have high concentration of 3-deoxyanthocyanins (i.e. luteolinidin and apigenidin) that give stable pigments at high pH. Pigmented and tannin sorghum varieties have high antioxidant levels that are comparable to fruits and vegetables. Finger millet has tannins in some varieties that contain a red testa. There are limited data on the phenolic compounds in millets; only phenolic acids and flavones have been identified.     

可食用野生蔬菜中纤维类物质的检测方法

依据GB/T 5009.88-2003食品中不溶性膳食纤维的测定(Determination of insoluble dietary fiber in foods)和GB/T 5009.10-2003植物类食品中粗纤维的测定(Determination of crude fiber in vegetable foods),并简化其操作步骤,对海南8种可食用野生蔬菜中的粗纤维和不溶性膳食纤维进行测定.结果表明,不同用量石油醚和α-淀粉酶对蔬菜中脂肪和淀粉进行前处理的作用不大.对测定结果几乎无影响;8种野生蔬菜中不溶性膳食纤维含量为1.5%～4.9%.粗纤维含量为0.7%～1.8%.     

Starchy legumes in human nutrition,health and culture

Starchy legumes have been consumed by humans since the earliest practice of agriculture and have been ascribed medicinal and cultural as well as nutritional roles. They are an important component of the diet in the developing countries in Africa, Latin America, and Asia where they are especially valuable as a source of dietary protein to complement cereals, starchy roots and tubers. Legumes contain 20–30% protein which is generally rich in lysine and limiting in sulfur amino acids. The nutritional quality of legume protein is limited by the presence of both heat labile and heat stable antinutrients as well as an inherent resistance to digestion of the major globulins. In addition to its nutritional impact, legume protein has been shown to reduce plasma low density lipoprotein when consumed. Legume starch is more slowly digested than starch from cereals and tubers and produces less abrupt changes in plasma glucose and insulin upon ingestion. Starchy legumes are also valuable sources of dietary fiber as well as thiamin and riboflavin. Starchy legumes are a valuable component of a prudent diet, but their consumption is constrained by low yields, the lack of convenient food applications, and flatulence.     

Commercial Breakfast Cereals Available in Mexican Markets and their Contribution in Dietary Fiber, β-Glucans and Protein Quality by Rat Bioassays

The beneficial effect of dietary fiber (DF) consumption has long been recognized. The global economy and open market trade policies have increased the availability of food products in Mexican markets, resulting in a wide variety of ready-to-eat commercial breakfast cereals classified as ‘high fiber’. This research was aimed to evaluate the total dietary fiber contents, its fractions (soluble and insoluble) and β-glucan in 13 commercial ‘high-fiber’ breakfast cereals, as well as to evaluate their protein quality by rat bioassays. Commercial ‘high-fiber’ breakfast cereals had 7.42–39.82 % insoluble dietary fiber, 2.53–12.85 % soluble dietary fiber, and 0.45–4.96 % β-glucan. These ready-to-eat commercial ‘high-fiber’ breakfast cereals differed significantly in their total dietary fiber, their soluble and insoluble DF fractions, and also in their β-glucan contents. When supplied as experimental diets, in 14-day rat feeding trials, the ‘high-fiber’ breakfast cereals showed an adverse effect on the % N digestibility but protein utilization, as measured as net protein ratio (NPR), was not significantly affected. The consumption of these commercial breakfast cereals, especially those made of oats as the basic ingredient, is highly recommended, since these products, being a concentrated source of dietary fiber, do not affect their protein quality.     

Evaluation of the selenium and chromium content of plant foods

In the present study the selenium and chromium content of different plant foods such as fruits, greens, flowers, vegetables, dried fruits, spices, condiments, cereals and pulses were analysed. The selenium values for cereals indehiscent vegetables, root vegetables, stem vegetables, pulses, fleshy vegetables, greens, fleshy fruits, condiment seeds, spices and dried fruits ranged between 24.2–32.16, 2.4–18.9, 2.8–21.5, 3.0–32, 48.7–92.5, 1.25–9.5, 3.0–8.2, 2.0–9.4, 6.2–66.2, 6.2–17.5 and 3.5–16.8 g/100 g respectively. The chromium values for the same ranged between 48.2–52.6, 31.0–45, 21.2–25.7, 23.7–62.8, 15.0–43.5, 20.4–65, 14.2–42.1, 14.25–46.7, 58.4–150 and 96–168 g/100 g respectively. Thus dried fruits have the highest chromium content and pulses the highest selenium content.     

Improving the Nutritional Value of Cool Season Food Legumes

Abstract

Cool season food legumes such as pea, lentil, chickpea, faba bean, grasspea and lupin have been consumed in animal and human diets since domestication and have been cultivated for over 9000 years. Due to their nutritional value they continue to make up a substantial portion of diets in developing countries worldwide. Seeds are composed of protein, starch, fiber, lipids, vitamins and minerals as well as several antinutritional compounds. Protein and starch combined account for 50-75% of seed mass. Similar amounts of protein and starch are present in each species and range from 15-40% and 35-53%, respectively. Fiber accounts for 1-22% of the seed mass. Chickpea is quite variable for fiber content, but faba bean, grasspea and lupin all contain approximately 15% fiber while pea and lentil have substantially lower levels, 4-8%. Protein composition is deficient in the sulfur amino acids, methionine and cysteine, but contains adequate levels of lysine making the legumes an excellent dietary complement to cereals. As a result these crops have been produced and consumed together for centuries. Despite the high nutritional value of these crops, they contain several antinutritional factors (ANF) such as phytic acid, protease inhibitors, heamagglutinins, tannins, alkaloids, raffinose oligosaccharides and antigenicity factors at relatively low levels. These compounds serve important roles in pest resistance or plant survival, but reduce digestibility and palatability when consumed. Genetic analysis of the antinutritional factors has shown that many of the ANFs are controlled by single genes and has allowed geneticists to reduce accumulation of the ANFs, thereby improving nutritional value. Legumes will continue to serve as the primary source of protein in areas of the world where meat is not readily available. Continued research toward a better understanding of the genetic control of legume quality will give geneticists the opportunity to improve the dietary value of these crops.     

By-Products of Opuntia ficus-indica as a Source of Antioxidant Dietary Fiber

Dietary fiber and bioactive compounds are widely used as functional ingredients in processed foods. The market in this field is competitive and the development of new types of quality ingredients for the food industry is on the rise. Opuntia ficus-indica (cactus pear) produces edible tender stems (cladodes) and fruits with a high nutritional value in terms of minerals, protein, dietary fiber and phytochemicals; however, around 20% of fresh weight of cladodes and 45% of fresh weight of fruits are by-products. The objective of this study was therefore to determine the nutritional value of by-products obtained from cladodes and fruits from two varieties of Opuntia ficus-indica, examining their dietary fiber and natural antioxidant compound contents in order to obtain quality ingredients for functional foods and increase the added value of these by-products.     

Enhancement of Bioactivity of Natural Extracts by Non-Thermal High Hydrostatic Pressure Extraction

Natural extracts, like those obtained from medicinal herbs, dietary plants and fruits are being recognized as important sources of bioactive compounds with several functionalities including antioxidant, anticancer, and antimicrobial activities. Plant extracts rich in phenolic antioxidants are currently being successfully used for several pharmaceutical applications and in the development of new foods (i.e., functional foods), in order to enhance the bioactivity of the products and to replace synthetic antioxidants. The extraction method applied in the recovery of the bioactive compounds from natural materials is a key factor to enhance the bioactivity of the extracts. However, most of the extraction techniques have to employ heat, which can easily lead to heat-sensitive compounds losing their biological activity, due to changes caused by temperature. Presently, high hydrostatic pressure (HHP) is being increasingly explored as a cold extraction method of bioactive compounds from natural sources. This non-thermal high hydrostatic pressure extraction (HHPE) technique allows one to reduce the extraction time and increase the extraction of natural beneficial ingredients, in terms of nutritional value and biological activities and thus enhance the bioactivity of the extracts. This review provides an updated and comprehensive overview on the extraction efficiency of HHPE for the production of natural extracts with enhanced bioactivity, based on the extraction yield, total content and individual composition of bioactive compounds, extraction selectivity, and biological activities of the different plant extracts, so far studied by extraction with this technique.     

Acceptability of supplementary foods based on popped cereals and legumes suitable for rural mothers and children

Eight types of supplementary foods based on popped cereals (wheat, ragi, bajra and sorghum) blended with legumes (soy and bengalgram) and fortified with essential vitamins and minerals were developed on a pilot plant scale. Four of the supplements were prepared with cereals, soy flour (SF) and bengal gram (BG) dhal and the other four were prepared with combinations of cereals and SF. These blends were mixed with jaggery (obtained by boiling juice out of sugarcane) syrup and pressed into compact form. One hundred gram portions of these foods provided 370 ± 20 kilocalories and 11 ± 1 g protein. Moisture, crude protein, total carbohydrates, total lipids, ash, dietary fiber and energy contents, of all the developed supplements were within the ranges prescribed by the Indian Standards Institute for processed weaning foods and could satisfactorily meet one-third of the Recommended Dietary Allowance (RDA) of these nutrients per day for preschool children. Organoleptic evaluation and feeding trials revealed that the foods were well accepted by rural mothers and children.     

海南15种野生蔬菜膳食纤维含量的测定

以国家标准GB 5009.88-2014《食品中膳食纤维的测定》为基础,研究了4种蛋白酶、2种酶解辅助处理方法对膳食纤维测定值的影响。以调整后的方法测定了15种野生蔬菜总的、可溶性及不溶性膳食纤维的含量,分析了不同产地和采摘时期野生蔬菜总膳食纤维含量的差异。结果表明:木瓜蛋白酶处理后的树仔菜总膳食纤维测定值最高;超声波振荡辅助酶解处理的除杂效果较好;15种野生蔬菜膳食纤维含量和组成差异较大,产地对树仔菜、马齿苋总膳食纤维含量的影响分别为极显著、显著,但是对枸杞菜和雷公菜总膳食纤维含量的影响不显著;采摘时期对树仔菜、马齿苋、枸杞菜和雷公菜总膳食纤维含量均有极显著影响。     

中国农作物生产及其贸易现状分析

运用中国2007~2017年FAO编码的农作物产量数据以及对应HS编码的农作物贸易数据,基于净进口依存度分析了谷类、豆类、薯类、纤维、油料、果类、蔬菜、其他等8类农作物的生产、贸易状况以及进出口安全状态,以期为我国从宏观上把握农作物的进出口及其生产安全提供参考。结果表明:(1)除了纤维、油料,其余农作物的产量均保持增长,其中粮食和果蔬的产量平均占整个农作物产量的87.47%;(2)大多年份,蔬菜和水果的进口量小于出口量,而其余农作物则相反;(3)纤维、油料类农作物的净进口依存度较大,处于危机状态,其余农作物的净进口依存度较小,处于安全状态。显然,我国在保持粮食类、果蔬类等大多数农作物产量增长的同时,需要关注油料类和纤维类作物的生产,至少应该保证一定的国内产量,在一定程度上避免过高的进口依赖。     

Relationship between dietary fiber levels and protein digestibility in selected foods as determined in rats

Samples of 15 food products and feces obtained by feeding them to rats were analysed for dietary fiber fractions. The food products were added as the sole source of protein in 8% protein diets, making up 8.8–51.6% of the diets. Diets were supplemented with 0.54–5.00% purified cellulose to make them more comparable in total fiber. Fiber analyses of food products revealed that the protein sources provided 0.06–7.27% total dietary fiber. The true protein digestibility in rats was negatively correlated with the total food fiber level (r=–0.69,P<0.01) or with the food cellulose level (r=–0.82,P<0.01) but it was positively correlated (r=+0.81,P<0.01) with the purified cellulose level. No relationship was found between protein digestibility and fiber fermentability. Results indicate that several food fiber fractions and possibly associated substances influenced protein digestibility. Purified cellulose did not have the same physiological behavior as food cellulose from the viewpoint of protein digestibility and fiber fermentability.     

Fibre constituents of some foods

Some plant foods viz. bottlegourd, carrot, cauliflower, cabbage, green bengalgram, pea, apple, plum, guava, karonda, blackgram husk and lentil husk were analysed for their dietary fibre components. The total dietary fibre contents of these foods varied from 14.68 to 78.21 percent on dry matter basis. As compared to fruits and vegetables, the husks had higher amount of total dietary fibre. Cellulose represented as the major fibre constituent in most of the foods whereas, husks were observed to be good sources of hemicellulose. All foods were low in pectin and lignin contents except guava.     

Effect of proccesing on dietary fiber content of cereals and pulses

Total dietary fiber (TDF), insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) content of rice, wheat, sorghum, maize, ragi, bajra, whole grains of pigeonpea, chickpea, green gram and lentil as well as their dehusked split dhals were analyzed. Cereals except rice flours were made into chapati (unleavened bread), while rice and dhals were cooked in a pressure cooker. After the processing, IDF and SDF contents of these foods were also analyzed. Among the cereals, rice had the lowest TDF (4.1%) and wheat had the highest (12.5%). TDF content of whole pulses ranged from 15.8% in lentil to 28.3% in chickpea. IDF as % of TDF constituted 85 to 89% in whole pulses. Dehusking of pulses into dhals decreased the TDF and IDF contents significantly. Among the dhals, green gram dhal had the lowest (8.2%, 6.5%) and chickpea dhal (15.3%, 12.7%) had the highest TDF and IDF contents, respectively. Processing of cereals had no effect on their TDF and IDF contents, rith the exception of ragi, where a significant increase in TDF and IDF was observed. Cooking of dhals brought about a significant increase in their TDF and IDF contents.