Promoting food security and enhancing Nigeria's small farmers' income through value-added processing of lesser-known and under-utilized indigenous fruits and vegetables

In Nigeria and other African countries, there are hundreds of lesser-known indigenous crops as well as other food plants gathered from the wild that contribute to food security and play vital roles in the nutrition of the people particularly the rural populace. These native crops and wild food plants that have received little research attention or extension activities and have been largely neglected by the mainstream of international science include a wide variety of wild indigenous fruits and vegetables that enrich the diet of the rural populace and could thrive with little care and without the use of costly agricultural inputs such as fertilizers, herbicides and pesticides. Among them are numerous fruits of Nigerian trees that grow wild in the rain forest and the woodland savanna zones or are cultivated on small, compound farms. These fruits that are consumed fresh are rich sources of nutrients including ascorbic acid, provitamin A carotenoids, minerals and nutraceuticals with health-promoting benefits. There is the need to promote the cultivation and utilization of many of these indigenous fruit trees including African star apple (Chrysophyllum albidum), African mango (Irvingia gabonensis), African or native pear (Dacryodes edulis) and hog plum (Spondias mombin) that are also of considerable environmental significance and protect them from uncontrolled wood felling activities that result in deforestation. Laboratory studies have shown that good quality fruit leathers, jams, juices and other drinks can be produced from several lesser-known and under-utilized Nigerian fruits and vegetables including African star apple (C. albidum), African mango (I. gabonensis), hog plum (S. mombin), tamarind (Tamarindus indica) and roselle (Hibiscus sabdariffa) using simple procedures suitable for small-scale commercial production including osmotic dehydration, open-kettle jam-making process and mechanical juice extraction followed by hot water pasteurization. Removing the constraints to the development of small-scale food industries which include inadequate electricity supply, use of inappropriate technology, inadequate working capital, high interest rates, and limited access to banks and other financial institutions would facilitate commercial production of these value-added foods in rural communities thereby reducing post-harvest losses, promoting food security, enhancing small farmers' income and contributing to sustainable rural development.     

Exploring new potential health‐promoting vegetables: glucosinolates and sensory attributes of rocket salads and related Diplotaxis and Eruca species

BACKGROUND: Rocket salads (Diplotaxis tenuifolia and Eruca vesicaria) are presently highly appreciated salad vegetables. Related species are consumed as food plants in several regions, and may contribute to differentiation in the fresh food supply chain. Glucosinolates are well‐known healthy phytochemicals and responsible for positive and negative sensory properties of edible Brassicaceae. To investigate the potential for exploitation of new crops, Diplotaxis and Eruca germplasm was subject to sensory evaluation and glucosinolate analysis. RESULTS: Typical rocket salad flavour and pungency were perceived as positive sensory traits. Bitter, and especially herbaceous notes, characterised the groups of less accepted accessions. The groups classified as significantly unpleasant were characterised by high glucosinolate content, with either sinigrin (strong perceived pungency, flavour and several other additional sensory notes), or sinalbin/gluconapin (strong herbaceous note, low flavour perceived), as the dominant components. CONCLUSIONS: Low glucosinolate content, and a composition rich in recognised health‐promoting components (glucoerucin, glucoraphanin) were associated with higher acceptance. In relation to food uses, moderate glucosinolate content and high acceptance may be a better option to enhance the intake of healthy phytochemicals than high glucosinolates and potential rejection. High glucosinolate types may find better perspectives in the field of food integrators. Copyright © 2009 Society of Chemical Industry     

Hydrolyzable tannin analysis in food

The discovery of plant polyphenols in food is perhaps one of the biggest breakthroughs in modern food science. Plant polyphenols are known for their role in food quality and safety, since they contribute significantly to taste, flavour, colour, stability etc., while they are increasingly recognised as important factors in long-term health, contributing towards reducing the risk of chronic disease. Almost 200years ago, hydrolyzable tannins (HTs) were the first group of plant polyphenols subjected to analytical chemical research. Despite the lack of commercially available standards, food analysis research offers a wealth of papers dealing with extraction optimisation, identification and quantification of HTs. The object of this review is to summarise analytical chemistry applications and the tools currently used for the analysis of HTs in food.     

Wild edible fruit diversity and its significance in the livelihood of indigenous tribals: Evidence from eastern India

A number of wild plants, used by rural and tribal populations and contributing significantly to their livelihood and food security have escaped recognition and scientific inquiry. Their distribution, conservation, mode of harvest by locals and optimal use require region-specific assessment in order to integrate them into developmental interventions. This study analyzed the collection, consumption, sale and income from edible forest fruits in 49 tribal villages spread over five districts of Orissa State in eastern India. Density, dominance and diversity of species yielding wild fruit were measured by studying ecological parameters in the sample plots. We estimated an average of 48 fruit plants per hectare of deciduous forests. Fifty-six wild edible fruit species belonging to 40 genera in 26 families were recorded in the study region, many of which have multiple uses. Indigenous fruits formed part of the family diet with average annual consumption of 73 kg per household. Sale of wild fruits contributed 15 % of income for tribal households. Despite their good knowledge of indigenous fruits, the tribal populations have not adopted fruit tree farming which would enhance their nutrition and income.     

Influence of health and taste attitudes on consumption of low- and high-fat foods

The present study investigated the relationship between health and taste attitudes and the total dietary behaviour as measured by a validated 104-item food frequency questionnaire. The study population consisted of 132 adults (mean 53 years of age, range 18–76 years; 82 women and 50 men). Health and taste attitudes were assessed by a validated questionnaire which consisted of three health sub-scales (general health interest, light product interest and natural product interest) and three taste sub-scales (craving for sweet foods, using food as a reward and pleasure). Dietary behaviour was expressed as nutrient intake and in terms of the intake of various types of foods (low-fat vs. high-fat foods). The health sub-scales general health interest and light product interest were good and useful predictors of dietary behaviour. General health interest was associated with a lower intake of fat, a lower consumption of high-fat savoury snacks and high-fat oils and fats, and an increased consumption of vegetables and fruit. Light product interest was associated with a higher consumption of low-fat dairy products and vegetables and fruit. The taste attitudes were not related to any type of dietary behaviour; only the taste sub-scale craving for sweet foods predicted food consumption of high-fat sweet snacks. In conclusion, general health interest was related to a more healthy food consumption pattern. Healthier food choices were made in line with nutrition education messages, but only with respect to those foods where the fat content was clearly visible.     

Rocket salad (Diplotaxis and Eruca spp.) sensory analysis and relation with glucosinolate and phenolic content

BACKGROUND: Salad crops of the Brassicaceae family, such as Diplotaxis tenuifolia and Eruca vesicaria, commonly referred to as ‘rocket salads’, have attracted considerable interest as culinary vegetables because of their strong flavour and their content of putative health‐promoting compounds. Among such compounds, glucosinolates and phenolics are well‐known phytochemicals with an important role also in determining the characteristic flavour of these species. In this study, to identify potentially high‐value rocket salads, 37 cultivated types were examined for sensory characters and their relations with glucosinolate and phenolic contents, which ranged from 0.76 to 3.03 g kg^?1 dry weight (DW) and from 4.68 to 31.39 g kg^?1 DW, respectively. RESULTS: The perception of bitter taste was significantly affected by specific glucosinolates, namely progoitrin/epiprogoitrin and dimeric glucosativin. Aroma intensity was negatively related to glucoalyssin content, whereas pungency was significantly related to total glucosinolate content. Kaempferol‐3‐(2‐sinapoyl‐glucoside)‐4′‐glucoside was positively and significantly related to all flavour trait perceptions. Aroma intensity, pungency, crunchiness and juiciness were positively related to typical rocket salad flavour perception through a prominent direct effect. CONCLUSION: Aroma intensity, pungency, crunchiness and juiciness were strong determinants of overall rocket salad flavour perception. Visual traits also characterised sensory components. Bitterness, usually considered a negative flavour trait, was moderately perceived in the examined material, without negatively affecting typical flavour perception. In the range of the examined material, glucosinolate content did not contrast with typical flavour, demonstrating that good taste and putative health‐promoting properties may coexist. Copyright © 2011 Society of Chemical Industry     

Odour–taste interactions: A way to enhance saltiness in low-salt content solutions

This study investigated odour–saltiness interactions in aqueous solutions. In a first experiment, 81 consumers indicated expected taste attributes for 86 labels of flavour related to common food items. Panellists were able to rate expected saltiness of food flavour evoked by food written items. Differences in expected saltiness were observed in relation to actual salt content of food. In experiment 2, we selected commercially available aromas corresponding to 14 of the salt-associated flavour labels found in experiment 1. Odour-induced saltiness enhancement was investigated for odours evoked by these aroma water solutions containing or not sodium chloride. Fifty-nine consumers rated odour and taste (bitterness, sourness, saltiness, and sweetness) intensity orthonasally and retronasally. Results showed that expected flavours could induce saltiness and enhance saltiness in solutions containing a low level of sodium chloride through odour-induced changes in taste perception. These results suggest that well selected odours could be used to compensate sodium chloride reduction in food.     

Assessment of phenolic content and free radical-scavenging capacity of some Thai indigenous plants

Ethanolic extracts from various parts of 26 Thai indigenous plants were examined for phenolic constituents and free radical scavenging capacity, to determine their potential as a source of natural antioxidants. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. The results showed that total phenolic compounds and flavonoid content were higher in seed extracts of berries used in wine production, while the levels in extracts obtained from herbs and vegetables were lower. Chewing plants which have an astringent taste gave a significantly higher total phenolic content and flavonoid content. Antiradical activity determined from 1/EC₅₀ by the DPPH radical-scavenging method was highest in wine production seeds and chewing plants. The correlation coefficient from regression analysis showed a positive relationship between total phenolic and total flavonoid content (r = 0.9). The results suggest that ethanolic extracts of some Thai indigenous plants exhibit a potential for use as natural antioxidants.     

From lesser‐known to super vegetables: the growing profile of African traditional leafy vegetables in promoting food security and wellness

There are hundreds of traditional leafy vegetables and wild food plants of horticultural and nutritional significance in Africa. These lesser‐known crops and wild food plants that are highly adapted to harsh growing conditions thrive with little care and are available when other sources of food fail or are out of season. They are rich in micronutrients and are often the cheapest sources of many essential vitamins and minerals in many localities. Many of them are very important functional foods in African traditional diets and are rich in nutraceuticals, including polyphenols, tannins, flavonoids and flavonols, that exert demonstrable antioxidant, free radical scavenging and enzyme inhibition activities and have antimicrobial properties that provide scientific justification and possible mechanisms for their use in the management of a wide range of ailments, including diet‐related, non‐communicable diseases such as diabetes, hypertension and cardiovascular diseases. African traditional leafy vegetables are invaluable in promoting food security and wellness in Africa on account of their availability and affordability, their great nutritional value, chemotherapeutic and health‐promoting properties and other unique qualities. Long recognised by the rural populace as quality food items, they are becoming more popular even with the more affluent urban elites. There is the need to develop improved management practices for these super vegetables to promote their cultivation and boost their exploitation for food security and wellness in Africa. © 2018 Society of Chemical Industry     

白菜-胡萝卜汁复合饮料的研制

白菜和胡萝卜都是营养价值很高的蔬菜,白菜富含纤维素,胡萝卜富含β-胡萝卜索。白菜和胡萝卜的混合蔬菜汁虽然营养丰富,但其口味令一些消费者不愉快,为了获得更多消费者的青睐,添加柠檬香精、苹果香精、西瓜香精,使白菜一胡萝卜汁复合饮料不仅具有白菜和胡萝卜特有香气,而且稍带果味,呈淡橙黄色,口感爽滑,不仅味道醇美而且营养丰富,还具有保健的功效,适合各类人群食用,是一类蔬菜保健型饮料。     

Juice blends--a way of utilization of under-utilized fruits, vegetables, and spices: a review

The post-harvest shelf life of maximum of fruits and vegetables is very limited due to their perishable nature. In India more then 20-25 percent of fruits and vegetables are spoiled before utilization. Despite being the world's second largest producer of fruits and vegetables, in India only 1.5 percent of the total fruits and vegetables produced are processed. Maximum amounts of fruit and vegetable juices turn bitter after extraction due to conversion of chemical compounds. In spite of being under utilized, the utilization of highly nutritive fruits and vegetables is very limited due to high acidity, astringency, bitterness, and some other factors. While improving flavor, palatability, and nutritive and medicinal value of various fruit juices such as aonla, mango, papaya, pineapple, citrus, ber, pear, apple, watermelon, and vegetables including bottle gourd, carrot, beet root, bitter gourd, medicinal plants like aloe vera and spices can also be used for juice blending. All these natural products are valued very highly for their refreshing juice, nutritional value, pleasant flavor, and medicinal properties. Fruits and vegetables are also a rich source of sugars, vitamins, and minerals. However, some fruits and vegetables have an off flavor and bitterness although they are an excellent source of vitamins, enzymes, and minerals. Therefore, blending of two or more fruit and vegetable juices with spices extract for the preparation of nutritive ready-to-serve (RTS), beverages is thought to be a convenient and economic alternative for utilization of these fruits and vegetables. Moreover, one could think of a new product development through blending in the form of a natural health drink, which may also serve as an appetizer. The present review focuses on the blending of fruits, under-utilized fruits, vegetables, medicinal plants, and spices in appropriate proportions for the preparation of natural fruit and vegetable based nutritive beverages.     

Influence of sulphate nutrition on the flavour components of garlic (Allium sativum) and wild onion (A. vineale)

Investigation of the relationship between the sulphate nutrition of garlic (Allium sativum) and wild onion(A. vineale) and their flavour strength is now reported. The plants were grown in a glasshouse in sand culture at two concentrations of sulphate in the nutrient medium and their flavour strength determined by sensory, biochemical and gas chromatographic methods. These observations have furnished further examples of environmental control of flavour components. The garlic plants in the two groups differed significantly in their fresh weights per plant. Their sulphur contents also showed that deficiency of this nutrient had been established in spite of the relatively large amount of sulphur introduced in the original cloves. The ratios of total sulphur content in the two groups of plants and of their flavour strengths as determined by total pyruvate values and taste threshold concentrations, respectively, were approximately constant (about 5). Total peak areas in the gas chromatograms increased with increasing (sensory) flavour strength. The garlic plants grown in sand culture were morphologically atypical, possibly because of the high moisture content of the growth medium, but their odour, taste and gas chromatograms were qualitatively indistinguishable from those of field-grown garlic which grew normally. Similar but more pronounced differences of flavour strengths were obtained with A. vineale and in this case the difference in flavour strengths between the deficient and normal plants was about 13-fold. The gas chromatograms of the deficient plants were almost completely lacking in the peaks which are characteristic of Allium sp. The discrepancies between initial and final sulphur contents of the deficient plants are discussed.     

香辛料在果蔬保鲜中的应用及研究进展

香辛料通常是指生长在热带地区的芳香植物的种子或者果实、根、树皮,常作为调料使用。香辛料在我国的使用已有悠久的历史。我国土地辽阔,植物资源种类繁多,香辛料植物作为植物的一部分,来源也十分丰富。香辛料不仅具有强烈的呈味、呈香作用,还有较强的抑菌防腐作用。从香辛料中提取的物质能够有效地抑制微生物的生长繁殖,延长果蔬的贮藏时间,保持果蔬原有的品质。果蔬采后保鲜与农业的发展有着密切关系,采用安全高效的天然植物源防腐剂运用于果蔬贮藏保鲜是将是今后研究的重点内容。本文介绍了香辛料的抑菌活性成分和保鲜机制,以及香辛料在水果和蔬菜贮藏保鲜中的应用及其研究进展。最后,对香辛料在果蔬保鲜中的应用提出了展望,为天然食品防腐剂的研究提供参考。     

Changes in functional properties of vegetables induced by high pressure treatment

Ultrahigh-pressure (UHP) hydrostatic exposure in excess of 100 MPa is being used to inactivate micro-organisms as well as to induce texture changes to foods without thermal degradation. The UHP process is said not only to preserve flavour and food product taste but also natural properties of biological products. The influence of high pressure on functional properties of a choice of vegetables was evaluated. The treatments were at pressures around 600 MPa and also in combination with elevated temperatures and in comparison with thermal treatment. Carrots, tomatoes and broccoli were investigated (crushed or liquid extracts). The following characteristics were assessed: content of health promoting substances (e.g. vitamins, antioxidants, antimutagens), effects on water retention, glucose retardation, changes in extractability, in-vitro bioavailability. In most cases high pressure did not induce loss of beneficial substances in the vegetable matrices but induced changes in the structure of the products which resulted in altered physico-chemical properties such as higher glucose retardation index and water retention or reduced extractability.     

Influence of sulphate nutrition on flavour components of three cruciferous plants: Radish (Raphanus sativus), cabbage (Brassica oleracea capitata) and white mustard (Sinapis alba)

The effect of sulphate nutrition on the flavour components of three members of the family Cruciferae (radish, cabbage and white mustard) has been investigated. The plants were grown in a glasshouse in sand culture at six concentrations of sulphate in the nutrient medium and their flavour characteristics determined by sensory and gas-chromatographic methods. The latter were based on (a) headspace samples from the raw and cooked vegetables and (b) solvent extracts chromatographed at 200°C. Sensory tests showed that the flavour strengths of the vegetables increased from low values at extreme sulphur deficiency to maxima with increase of the sulphate available to the plant. For radish and mustrad, there was no correlation between total volatile componets (determined by the headspace method) and sulphur content but a highly significant corelation was demonstrated between the latter and less volatile flavour components present in solvent extracts. In the case of mustrad seed. p-hydroxybenzyl isothiocyanate was determined colorimetrically and shown to be correlated with sulphur nutrition. With cabbage, allyl isothiocyanate and total volaile content were determined by a headspace method and each was found to be significantly correlated with sulphate nutrition. It is suggested that the flavour of these plants consists of at least two types of componnts: (a) compounds which impart a bland, generalised “vegetable” flavour to the food and (b) a specific component or components which are perceived as a burning sensation on the tongue sometimes accompanied by a characteristic odour. The former are independent of sulphur nutrition whilst the concentrations of the latter are highly correlated with sulphur nutrition. The effect of sulphate nutrition on growth response, visual deficiency symptoms and mineral composition has been reported.     

Plant carotenoids evolution during cultivation,postharvest storage,and food processing: A review

Carotenoids in nature are predominantly C40 hydrocarbons that may contain oxygenated functional groups. Although they are well‐recognized to exhibit key human health benefits, they cannot be synthesized in the human body and must be obtained from the diet. Fruit and vegetables are the primary dietary sources of carotenoids because plants automatically synthesize these compounds to protect cells from oxidative damage that may occur upon photosynthesis due to light. Biosynthesis and accumulation of carotenoids in plants begin during cultivation through postharvest storage. However, these compounds naturally degrade upon plant senescence and also during food processing (e.g., blanching, pasteurization, and drying). In this article, evolution of carotenoids during cultivation, postharvest storage, and food processing is comprehensively reviewed. Appropriate conditions and methods to cultivate, store, and process fruit and vegetables to help retard carotenoid degradation and enhance carotenoid biosynthesis are also reviewed and identified.     

Industry-Relevant Approaches for Minimising the Bitterness of Bioactive Compounds in Functional Foods: A Review

Functional foods, with their synergistic health benefits that go beyond just being a source of individual nutrients, present challenges to the traditional ‘nutrition’ view of foods. Consumers demand proven health benefits without compromising flavour, taste and colour. A successful functional food must offer nutrients, specific health-promoting functionality and desirable sensory attributes. Attempts to increase the intake of desirable bioactive compounds are driven by the need to deliver optimal bioactivity to consumers for disease prevention and health enhancement. Increasing the bioactive concentration in foods often leads to bitterness, particularly when incorporating bioactive phytochemicals. This article provides an overview of the strategies which can be used for food bitterness reduction, with an emphasis on those approaches which are industrially relevant and economically feasible, i.e. tailored food formulation, processing and delivery technology approaches. Solutions for reducing bitterness from phytochemicals in food are proposed, including blocking, inhibiting, suppressing, minimising and masking mechanisms. The potential of encapsulation and non-encapsulation approaches for functional food applications is highlighted, and their effect in improving stability, bioactivity, bioaccessibility and bioavailability is addressed.     

速冻蔬菜热烫处理的优化和节能

大多数速冻蔬菜必须经过热汤处理以保证其在冻藏期间质量的稳定性。但是热烫易引起蔬菜的色、香、味和质地的变化。目前蔬菜的热烫终点以过氧化物酶作为指示剂来确定。有关研究表明，以过氧化物酶的指示剂会导致某些蔬菜热烫过度，因此必须寻找对这蔬菜更合适的酶作为指示剂，以便优化热烫处理。在速冻蔬菜的热烫过程中要消耗大量的能量 和水，有一种热烫－冷却组合器可较好地解决蔬菜热烫过程的节能、节水问题。