Advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness

ABSTRACT

Biofortification aims to improve the micronutrient concentration of staple food crops through the best practices of breeding and modern biotechnology. However, increased zinc and iron concentrations in food crops may not always translate into proportional increases in absorbed zinc (Zn) and iron (Fe). Therefore, assessing iron and zinc bioavailability in biofortified crops is imperative to evaluate the efficacy of breeding programs. This review aimed to investigate the advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness. In vitro, animal and isotopic human studies have shown high iron and zinc bioavailability in biofortified staple food crops. Human studies provide direct knowledge regarding the effectiveness of biofortification, however, human studies are time consuming and are more expensive than in vitro and animal studies. Moreover, in vitro studies may be a useful preliminary screening method to identify promising plant cultivars, however, these studies cannot provide data that are directly applicable to humans. None of these methods provides complete information regarding mineral bioavailability, thus, a combination of these methods should be the most appropriate strategy to investigate the effectiveness of zinc and iron biofortification programs.     

Genetic variability in Musa fruit provitamin A carotenoids,lutein and mineral micronutrient contents

Bananas and plantains (Musa spp.) are a staple food for millions of impoverished people and as such are an important source of vitamins and micronutrients. To evaluate the potential of Musa spp. to meet dietary micronutrients requirements, we have screened 171 different genotypes for fruit provitamin A carotenoids (pVACs) contents, and a subset of 47 genotypes for macro- and micro-mineral (iron and zinc) contents using standardised sampling and analytical protocols. The results indicate that there is substantial variability in mean fruit pulp pVACs contents between cultivars, and that cultivars with a high fruit pVACs content are widely distributed across the different genome groups but only at a low frequency. The introduction of such high pVACs cultivars has much potential for improving the vitamin A nutritional status of Musa-dependent populations at modest and realistic fruit-consumption levels. In contrast, fruit pulp mineral micronutrient contents (iron and zinc), were low and showed limited inter-cultivar variability, even for genotypes grown under widely-differing environments and soil types. Results are discussed within the framework of the development of strategies to improve the nutritional health and alleviation of micronutrient deficiencies within Musa-consuming population groups.     

Bioaccessibility of provitamin A carotenoids in bananas (Musa spp.) and derived dishes in African countries

Bananas and plantains (Musa spp.) constitute an important component of the diet in Africa. Substantial levels of provitamin A carotenoids (pVACs) in Musa fruit have been reported, but the bioaccessibility of these pVACs remains unknown. In this study, we used an in vitro digestion model to assess the bioaccessibility (i.e. the transfer into micelles) of pVACs from boiled bananas and derived dishes using the Eastern Democratic Republic of Congo as a study context. In particular, the effect of different food ingredients added to boiled bananas on pVAC’s bioaccessibility was studied. The bioaccessibility of all-trans β-carotene ranged from 10% to 32%, depending on the food recipes, and was modified, particularly when pVACs-rich ingredients (palm oil/amaranth) were added. Efficiency of micellarization of all-trans β-carotene was similar to that of all-trans α-carotene and depended on the cultivar (Musilongo, plantain type, 16%; Vulambya, East African cooking type, 28%), while that of the 13-cis isomer was higher (21–33.5%). Taking into account bioaccessibility, the estimated vitamin A activity was significantly different across the different Musa-based dishes tested. Results are discussed in terms of recommendations to help reduce vitamin A deficiency in Musa-dependent African communities.     

Biofortification of mungbean (Vigna radiata) as a whole food to enhance human health

Mungbean (Vigna radiata (L.) R. Wilczek var. radiata) is one of the most important pulse crops grown in South, East and Southeast Asia. It provides significant amounts of protein (240 g kg^?1) and carbohydrate (630 g kg^?1) and a range of micronutrients in diets. Mungbean protein and carbohydrate are easily digestible and create less flatulence than proteins derived from other legumes. In addition, mungbean is lower in phytic acid (72% of total phosphorus content) than pigeonpea (Cajanus cajan L. Millsp.), soybean (Glycine max L.) and cereals; phytic acid is commonly found in cereal and legume crops and has a negative impact on iron and zinc bioavailability in plant‐based diets. Owing to its palatable taste and nutritional quality, mungbean has been used as an iron‐rich whole food source for baby food. The wide genetic variability of mineral concentrations (e.g. 0.03–0.06 g Fe kg^?1, 0.02–0.04 g Zn kg^?1) in mungbean indicates possibilities to improve its micronutrient content through biofortification. Therefore biofortification of existing mungbean varieties has great potential for enhancing the nutritional quality of diets in South and Southeast Asia, where protein and micronutrient malnutrition are among the highest in the world. This review paper discusses the importance of mungbean in agricultural production and traditional diets and the potential of enhancing the nutritional quality of mungbean through breeding and other means, including agronomic practices. © 2013 Society of Chemical Industry     

Retention of Provitamin A Carotenoids in Staple Crops Targeted for Biofortification in Africa: Cassava,Maize and Sweet Potato

HarvestPlus, part of the Consultative Group on Internation Agriculture research (CGIAR) Program on Agriculture for Nutrition and Health (A4NH) uses conventional plant breeding techniques to develop staple food crops that are rich in micronutrients, a food-based approach to reduce micronutrient malnutrition known as biofortification. The nutritional breeding targets are established based on the food intake of target populations, nutrient losses during storage and processing and bioavailability. This review collates the evidence on the retention of provitamin A carotenoid (pVAC) after processing, cooking, and storing of the staple crops targeted for pVAC biofortification: cassava, maize, and sweet potato. Sun drying was more detrimental to the pVAC levels (27–56% retention) in cassava than shade (59%) or oven (55–91%) drying, while the pVAC retention levels (66–96%) in sweet potato were not significantly different among the various drying methods. Overall, boiling and steaming had higher pVAC retention (80–98%) compared to baking (30–70%) and frying (18–54%). Gari, the most frequently consumed form of cassava in West Africa had the lowest pVAC retention (10–30%). The pVAC retention of maize grain and cassava and sweet potato flour reached levels as low as 20% after 1–4 months of storage and was highly dependent on genotype. Therefore, we recommend that an evaluation of the pVAC degradation rate among different genotypes be performed before a high pVAC crop is promoted.     

The microstructure and tannin content of banana fruit and their likely influence on juice extraction

Extraction of banana juice using the traditional physical method is limited to Mbidde banana cultivars. Most other banana cultivars (including Matooke cultivars) do not produce juice by this method. A study of the microstructure and tannin content of banana fruit (Mbidde and Matooke cultivars) was carried out in order to understand the underlying factors in the juice extraction process and develop a working hypothesis to explain the mechanism of juice separation. Microscopic examination of pulp sections of Mbidde bananas revealed that their microstructure contained many more intensely stained and larger laticifer cells than pulp tissues of Matooke cultivars. On ripening, the intensity of staining of laticifer cells in Mbidde fruit appeared to increase, while there was limited or no staining in fruit of Matooke cultivars. There was also higher tannin content in Mbidde than in Matooke bananas at both unripe and ripe stages. The high tannin concentration corresponding to the unique presence of high numbers of laticifer cells in fruit of Mbidde cultivars suggests that the ability of the bananas to release juice is linked to tannins. During juice extraction the physical working of the banana pulp ruptures the laticifer cells, resulting in the release of tannins that interact with celluloses, hemicelluloses, proteins and, most importantly, pectins to form insoluble complexes, thus facilitating juice release. Copyright © 2006 Society of Chemical Industry     

Profiles of carotenoids during post-climacteric ripening of some important cultivars of banana and development of a dry product from a high carotenoid yielding variety

Since vitamin A deficiency is prevalent in many developing countries, we sought to focus research on local, affordable and well-accepted sources of provitamin A carotenoids. As dessert bananas are consumed fresh round the year and processed as products, this study investigated whether post-climacteric biochemical changes are linked to carotenoid degradation in four Indian varieties, one commercial (Cavendish, AAA), one Red banana (genome AAA) and two locally-important ones (genome AAB). Despite large differences in their ripening characteristics, textural loss was lesser in AABs than AAAs. High levels of carotenoids (21.0 μg/g FW), β-carotene (9.14 μg/g FW) and α-carotene (9.32 μg/g FW) were found in Red banana accounting for retinol activity equivalent of 114 μg/100 g FW. The carotenoid levels were lower in two local varieties and lowest in Cavendish, with no post-climacteric loss. Dry grits, prepared using Red banana pulp, milk powder and sugar, retained about 70% carotenoids and appeared useful in confectionaries.     

基于成熟度研究不同品种香蕉多酚含量及抗氧化活性的差异

为评价新品种GC30加工蕉的抗氧化功效,开发其相关产品,拓宽香蕉产业链,本文以GC30加工蕉和4个主栽品种GC02天宝高蕉、GC07鸡蕉、GC09粉蕉、GC25大蕉为对象,研究不同成熟度（1级和7级,1级全果呈暗绿色,7级全果呈黄色）下香蕉皮、肉及果的多酚含量和抗氧化活性,并基于主成分分析法,对不同品种及成熟度香蕉抗氧化活性进行综合评价。结果表明,所有品种的香蕉皮多酚含量均最高（P<0.01）,7级香蕉皮、肉的多酚含量与其1级的没有显著性差异（P>0.05）,不同品种的香蕉皮多酚含量具有显著性差异（P<0.05）,其中7级GC30香蕉皮的多酚含量最高;不同品种的香蕉果、肉、皮的DPPH自由基清除率、超氧阴离子自由基清除能力和抑制羟自由基能力没有显著性差异（P>0.05）,所有品种的7级香蕉皮、肉、果的DPPH自由基清除率、超氧阴离子自由基清除能力和抑制羟自由基能力极显著高于其1级香蕉皮、肉、果（P<0.01）;所有品种的香蕉皮金属螯合率极显著大于香蕉果、肉（P<0.01）,而品种和成熟度对香蕉皮、肉、果的金属螯合率没有显著影响（P>0.05）;不同品种熟香蕉果、肉、皮的抗氧化活性优于生香蕉果、肉、皮的抗氧化活性,其中7级GC30香蕉皮抗氧化活性综合评价排名最高。通过对不同品种和成熟度香蕉的功效成分及抗氧化能力的研究,为香蕉品种的选育、分级分类加工与应用提供理论依据,对增加香蕉产业的收益具有重要意义。     

Effect of processing and oil type on carotene bioaccessibility in traditional foods prepared with flour and puree from orange-fleshed sweetpotatoes

Consumption of Orange-Fleshed sweetpotato (OFSP) and products as source of provitamin A is being promoted to tackle vitamin A deficiency (VAD) in sub-Saharan Africa. However, limited information is available on β-carotene retention in foods and delivery after digestion. The study assessed carotene retention and bioaccessibility following in vitro digestion on traditional foods having OFSP among the ingredients. Sunflower oil, margarine and beef fat were evaluated on their effect on β-carotene bioaccessibility. Porridge and chapatis were prepared with either OFSP puree or flours in the formulations. Carotene retention was highest in chapatis (83%) as compared to porridge (65%). Micerallisation efficiency of all-trans β-carotene was comparable between similar products but greater in chapatis (62%) than porridge (11%). Sunflower oil had the highest all-trans β-carotene bioaccessibility compared to margarine and beef fat. The results support the promotion of consumption of OFSP-based products as good source of provitamin A to fight VAD.     

Carotenoid-rich bananas: a potential food source for alleviating vitamin A deficiency

This review article points out that bananas are an important food for many people in the world. Thus, banana cultivars rich in provitamin A carotenoids may offer a potential food source for alleviating vitamin A deficiency, particularly in developing countries. Many factors are associated with the presently known food sources of vitamin A that limit their effectiveness in improving vitamin A status. Acceptable carotenoid-rich banana cultivars have been identified in Micronesia, and some carotenoid-rich bananas have been identified elsewhere. Bananas are an ideal food for young children and families for many regions of the world, because of their sweetness, texture, portion size, familiarity, availability, convenience, versatility, and cost. Foods containing high levels of carotenoids have been shown to protect against chronic disease, including certain cancers, cardiovascular disease, and diabetes. Because the coloration of the edible flesh of the banana appears to be a good indicator of likely carotenoid content, it may be possible to develop a simple method for selecting carotenoid-rich banana cultivars in the community. Research is needed on the identification of carotenoid-rich cultivars, targeting those areas of the world where bananas are a major staple food; investigating factors affecting production, consumption, and acceptability; and determining the impact that carotenoid-rich bananas may have on improving vitamin A status. Based on these results, interventions should be undertaken for initiating or increasing homestead and commercial production.     

基于深度学习的香蕉成熟度自动分级

目的:快速、准确分类香蕉成熟度。方法:采集不同成熟度的香蕉图像并建立图库,利用多种神经网络作为分类器提取香蕉特征,通过迁移学习对香蕉6个成熟度等级进行分类,并对最适合进行香蕉成熟度分类的网络模型进行改进,设计简易香蕉成熟度实时检测界面,最后验证模型的可行性和实用性。结果:AlexNet模型最适合用于香蕉成熟度分类,准确率最高,可达到95.56%;通过修改其全连接层结构改进AlexNet模型,模型准确率再提升1.11%。结论:AlexNet模型可快速准确识别并分类不同成熟度的香蕉。     

Effects of variety and stage of fruit ripeness on the physicochemical and sensory characteristics of deep‐fat‐fried banana chips

The quality of banana chips prepared from two different varieties of banana, Pisang Abu and Pisang Nangka, at the ‘green’ and ‘trace of yellow’ stages of ripeness was studied. The fruits were peeled, sliced to a thickness of 2 mm and deep‐fat fried in refined, bleached and deodorised (RBD) palm olein at 180 ± 5 °C for 3 min. The quality parameters determined for fresh bananas were total soluble solids, pH, acidity, carbohydrate, sugar content, fat, protein, moisture content, ash, fibre, colour and fruit firmness. The results showed that Abu had a higher carbohydrate content than Nangka at both stages of ripeness before frying. No sucrose was detected in Nangka. The quality parameters determined after deep‐fat frying were moisture content, water activity, oil absorption, crispness and sensory evaluation. The moisture content and water activity of Abu chips were lower than those of Nangka chips. The texture of chips prepared from Abu at stage ‘green’ showed more crispness than the other three samples. Sensory evaluation showed that chips prepared from Abu at both stages of ripeness presented better colour, flavour, odour, texture and overall acceptability than those prepared from Nangka. Based on the matrix of correlation coefficients, fresh bananas with higher fruit firmness and carbohydrate content gave banana chips with higher crispness and oil absorption. © 2001 Society of Chemical Industry     

Banana: cultivars,biotechnological approaches and genetic transformation

Genetic modification of banana has been considered as a path towards increasing the value of this crop according to health and nutrition in developing countries. Banana as a crop is one of the most important and widely consumed fruits as a weaning food by children and as a starchy staple for all other consumers. As well as providing a low cost and easily produced source of energy, bananas are also rich in certain minerals and in vitamins A, C and B6. Growing urbanisation in many developing countries upgraded the crop importance as a source of revenue, occasionally providing the main source of income for rural communities. Genetically modified organism bananas have been advocated as carrier for vaccines and as a source of carotenoids that can counteract debilitating vitamin A deficiency. The rather high vulnerability of banana to pests and diseases triggered biotechnological applications in an attempt to produce new, more resistant banana cultivars. However, the potential biosafety of genetically modified banana and its applications should be taken into account prior to its extensive usage. The current survey summarises the most important biotechnological techniques (in vitro culture, DNA fingerprinting, somatic emrbyogenesis, DNA flow cytometry, etc.) and applications (micropropagation, in vitro selection, somaclonal variation, protoplast fusion, haploid production, etc.) in banana and emphasises on genetic transformation in conjunction with the expressed gene and modified trait aiming at a further improvement of this crop.     

Insights into the role of bacteria in vitamin A biosynthesis: Future research opportunities

Abstract

Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iodine, and vitamin A since the beginning of the 21st century. Prioritizing the vitamin A deficiency (VAD) disorders, many countries are looking for viable alternative strategies such as biofortification. One of the leading causes of VAD is the poor bioconversion of β-carotene into retinoids. This review is focused on the opportunities of bacterial biosynthesis of retinoids, in particular, through the gut microbiota. The proposed hypothesis starts with the premise that an animal can able to store and timely convert carotenoids into retinoids in the liver and intestinal tissues. This theory is experimental with many scientific insights. The syntrophic metabolism, potential crosstalk of bile acids, lipocalins and lipopolysaccharides of gut microbiota are reported to contribute significantly to the retinoid biosynthesis. The gut bacteria respond to these kinds of factors by genetic restructuring driven mainly by events like horizontal gene transfer. A phylogenetic analysis of β-carotene 15, 15′-mono (di) oxygenase enzymes among a selected group of prokaryotes and eukaryotes was carried out to validate the hypotheses. Shedding light on the probiotic strategies through non-genetically modified organism such as gut bacteria capable of synthesizing vitamin A would address the VAD disorders.     

Physical properties and carotenoid content of maize kernels and its nixtamalized snacks

Vitamin A and protein deficiencies afflict hundreds of millions of people, and because maize is a staple food providing a large portion of energy and nutrients for many, its genetic fortification or biofortification could significantly contribute to alleviating malnutrition. Therefore, we measured carotenoid and tryptophan contents for grain, nixtamalized (lime-cooked) maize, and processed snacks of 13 maize genotypes including landraces, quality protein maize (QPM) and non-QPM hybrids. An average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying. The correlations for physical properties of grain and maize flour with provitamin A were calculated to investigate whether secondary traits may be useful as indicators of provitamin A content. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), but was not significant for whole maize kernels.Industrial relevanceYellow maize is used as food and feed. Possible methodologies for rapid carotenoid estimation for industrial purposes like corn flakes or for the poultry industry will be of importance. One of the objectives of this work was to establish correlation between physical parameters and carotenoid concentration in maize. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), which could be explored as a methodology for rapid and inexpensive estimation of provitamin A and total carotenoids in maize. Lime-cooking is the traditional method for maize preparation in Mexico and Central America. The estimation of carotenoid losses during this process and the bioavailability studies are important to measure the impact of biofortified maize in the populations with provitamin A deficiencies. During this work we have determined that an average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying.     

Analysis of carotenoids in ripe jackfruit (Artocarpus heterophyllus) kernel and study of their bioconversion in rats

Vitamin A deficiency is of public health importance in Sri Lanka. Carotenoids are a significant source of provitamin A. The objective of this study was to analyse the carotenoid composition of jackfruit (Artocarpus heterophyllus sinhala: Waraka) kernel using MPLC and visible spectrophotometry and to determine the bioavailability and bioconversion of carotenoids present in jackfruit kernel by monitoring (i) the growth and (ii) levels of retinol and carotenoids in the liver and serum of Wistar rats provided with jackfruit incorporated into a standard daily diet. Carotenoid pigments were extracted using petroleum ether/methanol and saponified using 10% methanolic potassium hydroxide. Six carotenoids were detected in jackfruit kernel. The carotenes β‐carotene, α‐carotene, β‐zeacarotene, α‐zeacarotene and β‐carotene‐5,6‐epoxide and a dicarboxylic carotenoid, crocetin, were identified, corresponding theoretically to 141.6 retinol equivalents (RE) per 100 g. Our study indicated that jackfruit is a good source of provitamin A carotenoids, though not as good as papaya. Serum retinol concentrations in rats supplemented with jackfruit carotenoids were significantly higher (p = 0.008) compared with the control group. The same was true for liver retinol (p = 0.006). Quantification was carried out by RP‐HPLC. These results show that the biological conversion of provitamin A in jackfruit kernel appears satisfactory. Thus increased consumption of ripe jackfruit could be advocated as part of a strategy to prevent and control vitamin A deficiency in Sri Lanka. Copyright © 2004 Society of Chemical Industry     

The development and release of maize fortified with provitamin A carotenoids in developing countries

Micronutrient deficiencies have been identified as major public health problems affecting a large part of the world's population. Biofortification of staple crops like maize has been proposed as one of the most cost effective and feasible approaches to combat micronutrient deficiencies. Studies have shown that provitamin A from biofortified crops is highly bioavailable and has the capacity to improve vitamin A status of vulnerable groups. Most people in sub-Saharan Africa subsist on maize and many people may benefit from consumption of provitamin A carotenoid biofortified maize, especially women and children. With the exception of transgenic golden rice, biofortified crops have received considerable acceptance by most communities. Negative perceptions associated with yellow maize do not affect orange maize, which is, for example, well-liked in rural Zambia. With proper policy frameworks and full commercialization, provitamin A maize can address the problem of vitamin A deficiencies among poor nations with maize-based diets.     

Proximate composition,provitamin A retention,and shelf life of extruded orange‐fleshed sweet potato and bambara groundnut‐based snacks

Evaluating the effect of processing on nutrient content and shelf life is important when developing new products. Six formulations of orange‐fleshed sweet potato (OFSP) and bambara groundnut were extruded at a feed rate of 10.15 kg/hr, screw speed of 30 rpm and at 100 and 130 °C in first and second zones respectively. Proximate composition was determined using standard methods. Provitamin A was determined using high‐performance liquid chromatography. An untrained panel (n = 73) was used to determine consumer acceptability. Shelf life was predicted by using peroxide values. Concentration of OFSP or bambara groundnut significantly (p < .05) affected proximate composition of the snacks. Moisture (4.79–8.34 g/100 g), carbohydrates (55.53–78.99 g/100 g) and provitamin (0.54–17.33 mg/100 g) contents increased with increase in proportion of OFSP. Protein (4.08–15.03 g/100 g), fat (4.20–12.74 g/100 g), fiber (5.29–6.46 g/100 g), ash (0.09–4.80 g/100 g), and energy (366.13–396.9 kcal/100 g) increased with increasing proportion of bambara groundnut in the formulation. Extrusion significantly (p < .05) reduced provitamin A content from 0.90–20.73 to 0.54–17.33 mg/100 g. Presence of OFSP improved provitamin A retention and consumer acceptability. Predicted shelf life (ranged from 118 to 150 days at room temperature) was inversely proportional to the concentration of bambara groundnut.

Practical applications

Vitamin A deficiency (VAD) is the leading cause of preventable blindness affecting many children and women of reproductive age globally. Provitamin A enriched foods can be developed from locally available provitamin A‐rich foods and their consumption promoted to help prevent VAD. In this study, recipes incorporating orange‐fleshed sweet potatoes and bambara groundnut were used to develop acceptable and shelf stable vitamin A enriched extruded snacks. The formulations and process used in this study can be adopted at commercial level to produce affordable snacks that can contribute towards reducing the burden of VAD. The results from this study can also be used in similar studies to develop nutrient enhanced extruded snacks.     

Bioavailability of iron and zinc from multiple micronutrient fortified beverage premixes in Caco-2 cell model

Abstract: Iron and zinc deficiencies are the most prevalent nutrient deficiencies worldwide. They often coexist as the dietary factors, especially phytate, which impairs iron absorption also affects zinc absorption. Therefore, suitable strategies are required to control multiple micronutrient deficiencies in populations that subsist on high‐phytate foods such as the whole wheat flour based Indian bread (chapatti). The objective of the study, therefore, was to test the bioavailability of iron and zinc in 2 multiple micronutrient beverage premixes in the absence and presence of chapatti. The premix‐1 contained iron, zinc, and vitamin A while premix‐2 contained all micronutrients in premix‐1, plus folic acid and ascorbic acid. Ferritin induction and ⁶⁵Zn uptake were assessed using coupled in vitro digestion/Caco‐2 cell line model as the surrogate markers of iron and zinc bioavailability, respectively. The results show that iron bioavailability from premixes‐1 and 2 was similar in the absence of chapatti. However, premix‐2 showed significantly higher iron bioavailability compared to premix‐1 in the presence of chapatti. In contrast, the zinc uptake was similar from both premixes‐1 and 2 in the absence or presence of chapatti. These results suggest that both the premixes provide bioavailable minerals, but premix‐2 appears to be promising in the presence of foods that have high phytate.