Effects of husk and harvest time on carotenoid content and acceptability of roasted fresh cobs of orange maize hybrids

Variations in micronutrient concentrations and retentions in fufu made from yellow-fleshed cassava as a function of genotype and processing methods

Introduction

The biofortification of staple foods such as cassava is one of the technological breakthroughs in the nutritional improvement of foods. Fufu is one of the fermented cassava products produced and consumed in major West African countries, including Sierra Leone, and the majority of the processes involved in its production have direct and indirect effects on its properties. This study looked at how the concentration and retention of micronutrients in yellow-fleshed cassava fufu varied depending on genotype and processing method.

Methods

Six yellow-fleshed cassava root genotypes (TMS-070557, TMS-011371, TMS-011412, TMS-011663, TMS-083724, TMS-083774) and one white (TME 419 as a control) were processed into fufu using both conventional (oven and sun-dried) and traditional (bowl and river) methods. The Statistical Analysis System (SAS) version 9.4 was used to analyze data using means, percentages, analysis of variance and means separated by least significant differences (LSD).

Results and Discussion

In the modified traditional river method, raw and cooked fufu samples had significantly higher β-carotene concentrations and true retention (TR) percentages (11.06  g/g (46.77%) and 4.54 g/g (16.94%), respectively) than other genotypes (p  <  0.0001). Modified traditional fufu processing methods increased total β-carotene concentrations, while raw roots showed a significant decrease in total carotenoid and β-carotene concentrations, regardless of genotype or processing method. Sun-drying was the most effective method, with significantly higher concentrations and TR percentages of iron (10.01  mg/kg, 18.02%) and zinc (11.49  mg/kg, 40.64%) in raw and cooked fufu samples. Genotype TMS-083724 outperformed both conventional fufu processing methods, displaying a significant total carotenoid concentration and true retention percentage. Finally, this study found that the concentrations and percentages of TR of micronutrients varied depending on the processing method and genotype. It is recommended that a modified traditional river fufu processing method be further developed and improved in order to maximize provitamin A carotenoids, concentrations, and percentage TR.

A combination of QTL mapping and genome-wide association study revealed the key gene for husk number in maize

KEY MESSAGE

Two key genes Zm00001d021232 and Zm00001d048138 were identified by QTL mapping and GWAS. Additionally, they were verified to be significantly associated with maize husk number (HN) using gene-based association study. As a by-product of maize production, maize husk is an important industrial raw material. Husk layer number (HN) is an important trait that affects the yield of maize husk. However, the genetic mechanism underlying HN remains unclear. Herein, a total of 13 quantitative trait loci (QTL) controlling HN were identified in an IBM Syn 10 DH population across different locations. Among these, three QTL were individually repeatedly detected in at least two environments. Meanwhile, 26 unique single nucleotide polymorphisms (SNPs) were detected to be significantly (p < 2.15 × 10-6) associated with HN in an association pool. Of these SNPs, three were simultaneously detected across multiple environments or environments and best linear unbiased prediction (BLUP). We focused on these environment-stable and population-common genetic loci for excavating the candidate genes responsible for maize HN. Finally, 173 initial candidate genes were identified, of which 22 were involved in both multicellular organism development and single-multicellular organism process and thus confirmed as the candidate genes for HN. Gene-based association analyses revealed that the variants in four genes were significantly (p < 0.01/N) correlated with HN, of which Zm00001d021232 and Zm00001d048138 were highly expressed in husks and early developing ears among different maize tissues. Our study contributes to the understanding of genetic and molecular mechanisms of maize husk yield and industrial development in the future.

Assessment of Functional and Pasting Properties of Fresh Orange Maize Hybrids and Open-Pollinated Varieties as Influenced by Genotype, Harvesting Time, and Growing Location

The study evaluates the effects of genotype, maturity, and growing location on the functional and pasting properties of freshly harvested orange maize hybrids and open-pollinated varieties (OPVs). Eight fresh orange maize hybrid and eight fresh maize OPV, including the control, were harvested at three stages: 20, 27, and 34 days after planting (DAP). The freshly harvested maize samples were lyophilized and characterized for the pasting and functional properties using standard laboratory methods. The peak viscosity, final viscosity, and swelling power of the OPVs increased between 20 and 27 DAP. Additionally, the water absorption capacity increased between 20 and 27 DAP for the maize hybrids, with a decreasing trend between 27 and 34 DAP. However, genotypes 2, from the orange maize hybrid, and 5, amongst the OPV, were outstanding with the highest peak viscosities, indicating good final product quality. The combined ANOVA for the fresh orange maize hybrid and OPV showed a highly significant effect (p ≤ 0.01 and p ≤ 0.001) for the maturity and location on the pasting and functional properties except for the pasting temperature, final viscosity, and pasting time which showed no significant effect. In contrast, the location by genotypes by maturity interactions had no significant effects on the pasting and functional properties of the fresh maize hybrid and the orange OPV except only for the setback, which was highly significant at p ≤ 0.001. Nutritionists, food scientists, and maize breeders could use the information from this study to select the best maize genotypes at the appropriate harvesting period suitable for the production of the preferred maize-based products of consumers.

Nutritional Properties of Ogi Powder and Sensory Perception of Ogi Porridge Made From Synthetic Provitamin: A Maize Genotype

Provitamin-A maize (PVA) with increased carotenoid content obtained through conventional breeding techniques has been largely successful in sub-Saharan Africa. This resulted in a need to evaluate their susceptibility, retention, and nutritional content during processing into local foods. This study evaluated the chemical, carotenoid composition, and retention of PVA, the phytic acid content in ogi powder, and the sensory perception of ogi porridge produced traditionally from the three novel PVA maize genotypes (PVA SYN HGAC0 Maize 1; PVA SYN HGBC0 Maize 2; and PVA SYN HGBC1 Maize 3) and one yellow maize variety (control). Chemical composition analyses showed significant differences (p < 0.05) in all parameters. The PVA ranged from 5.96 to 8.43 μg/g in Maize 2 and 3 before processing while the true percentage retention after processing into ogi powder ranged from 20.25 to 37.54% in Maize 1 and 2, respectively. In addition, there was a reduction in the phytate content of ogi powder, and Maize 2 contained the lowest (2.78 mg/g from 4.09 mg/g). Maize 2 genotype had the highest vitamin A contribution; it can meet 18.3% of the vitamin A requirements in children while in adult males and females (>19 years), 6.2 and 7.7%, respectively. Sensory evaluation showed that the ogi 3 porridge (Maize 3) was the most acceptable, followed by Maize 2. In conclusion, Maize 2 had the highest PVA, true retention of carotenoid, vitamin A contributions, and the second most acceptable ogi porridge with the lowest phytate content.

Bioactive Composition and Free Radical Scavenging Activity of Fresh Orange Maize Hybrids: Impacts of Genotype, Maturity Stages, and Processing Methods

Bioactive compounds in foods are responsible for their biological activities, but biotic and abiotic factors may influence their levels. This study evaluated the impact of three genotypes (designated 4, 5, and 7), maturity stages (20, 27, and 34 days after pollination) and processing methods (hydrothermal and dry-heating) on the bioactive constituents (carotenoids, phytate, tannins, vitamin C) and 2,2-diphenyl-2-picrylhydrazyl radical (DPPH^*) scavenging activity of fresh orange maize hybrids. Freshly harvested maize cobs of each genotype were subjected to hydrothermal processing at 100°C and dry-heating with husks and without husks. Carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and total β-carotene) contents of fresh and processed samples were analyzed using HPLC; other bioactive constituents and DPPH^* scavenging ability were determined using spectrophotometric methods. Genotype had a significant effect on the levels of carotenoids (p < 0.001) and vitamin C (p < 0.05), while genotype (p < 0.001), and processing methods (p < 0.001) had significant effects on DPPH^* SC₅₀. Maturity stages, processing methods and their interaction also had significant effects (p < 0.001) on the levels of all the bioactive constituents. A positive moderate to strong correlation was observed between (p < 0.001) α-carotene and the following: lutein (r = 0.57), β-cryptoxanthin (r = 0.69), total β-carotene (r = 0.62). However, the relationship between α-carotene and zeaxanthin was positive but weak (r = 0.39). A positive moderate correlation (p < 0.001) was observed between lutein and the following: β-cryptoxanthin (r = 0.57), total β-carotene (r = 0.58), and zeaxanthin (r = 0.52). A positive strong correlation (p < 0.001) was observed between β-cryptoxanthin and each of total β-carotene (r = 0.92) and zeaxanthin (r = 0.63); total β-carotene and zeaxanthin (r = 0.65); while the association between vitamin C and DPPH^* SC₅₀ was negative and weak (r = −0.38). Generally, genotype 4 and harvesting at 34 days after pollination had the best combination of bioactive constituents and DPPH^* scavenging ability.

Harvesting time and roasting effects on colour properties, xanthophylls, phytates, tannins and vitamin C contents of orange maize hybrid

Biofortified maize varieties form an essential part of a nutritious diet; available evidence suggests that different processing methods may affect the final food products. The study aimed to evaluate the effects of processing (roasting) and harvesting time on the bioactive components (lutein, zeaxanthin, β-cryptoxanthin, phytate, tannin and vitamin C) and colour properties (L*, a*, b*), of biofortified orange maize. The orange maize hybrids used for the study were obtained from the International Institute of Tropical Agriculture (IITA) diverse lines with high provitamin A (PVA) content. The results showed that harvesting time and roasting methods significantly (P ≤ 0.001) affected the colour properties. The positive values of ∆b* 30.7, 36.0 and 38.1 at 20 days after pollination (DAP), 27DAP and 34DAP, respectively showed that the intensity of orange colour increased with delay in harvesting time. In unprocessed freshly harvested orange hybrid maize; lutein, zeaxanthin, β-cryptoxanthin, tannin and vitamin C increased with an increase in harvesting time. For roasted hybrid, the mean concentrations of all the bioactive components increased with increases in harvesting time except for tannin and vitamin C that showed a decrease at 20DAP and 27DAP. The results revealed that processing and time of harvest affect the levels of non-provitamin A carotenoids, tannins, phytic acid, Vitamin C and the colour properties of biofortified maize genotypes.

Evaluation of Quality and Acceptability of Snack (Kokoro) Produced From Synthetic Provitamin A Maize (Zea mays) Genotypes

Kokoro from provitamin A (PVA) maize genotypes, produced through conventional breeding, was studied to improve the indigenous white maize-based snack deficient in provitamin A carotenoid commonly consumed in South-western Nigeria. The chemical composition, carotenoid retention, and acceptability of Kokoro from three PVA maize genotypes and one landrace yellow maize variety (control) were estimated. Chemical composition showed significant differences (p &lt; 0.05) in parameters with high crude fat content (23.21–32.11%). The sensory evaluation result revealed that Kokoro from DT STR SYN2-Y (control) was the most acceptable, while among the PVA Kokoro, PVA SYN HGBC1 was acceptable. The pre-processing for the estimated carotenoids (μg g−1); lutein, zeaxanthin, total β-carotene, and PVA in maize genotypes ranged from 10.38 to 12.87, 6.03 to 10.97, 3.83 to 6.18, and 5.96 to 8.43, while after processing to Kokoro, total β-carotene ranged from 1.47 to 3.10 μg g−1 and total PVA content 2.43–4.00 μg g−1. The carotenoid retention in Kokoro from PVA maize genotypes ranged from zeaxanthin 5.89–8.39%; lutein 2.74–4.45%; total β-carotene 38.24–66.14%, and total PVA 37.98–67.05%. Degradation of carotenoid was observed due to the unit operations in the processing method that led to the exposure of the food matrix to direct sunlight, heat, light, metals, and oxygen resulting in the formation of cis-isomers and loss of provitamin A quantity. The maize genotype PVASYNHGBC0 had the highest PVA value and carotenoid retention after processing. The study observed that PVA retention of Kokoro was genotype-dependent, and genotype PVASYNHGBC0 (Provitamin A maize HGA cycle zero) retained the highest carotenoid content. Also, PVASYNHGBC0 (for all the servings' size; 100 and 150 g) in all age groups had the highest percentage contribution of vitamin A to the recommended daily allowance. However, further improvement in the carotenoid content of maize genotypes is needed to enable the production of nutritious Kokoro with higher vitamin A percentage contribution and retinol equivalent.

Mining maize diversity and improving its nutritional aspects within agro-food systems

Agro-food systems are undergoing rapid innovation in the world and the system's continuum is promoted at different scales with one of the main outcomes to improve nutrition of consumers. Consumer knowledge through educational outreach is important to food and nutrition security and consumer demands guide breeding efforts. Maize is an important part of food systems. It is a staple food and together with rice and wheat, they provide 60% of the world's caloric intake. In addition to being a major contributor to global food and nutrition security, maize forms an important part of the culinary culture in many areas of Africa, the Americas, and Asia. Maize genetics are being exploited to improve human nutrition with the ultimate outcome of improving overall health. By impacting the health of maize consumers, market opportunities will be opened for maize producers with unique genotypes. Although maize is a great source of macronutrients, it is also a source of many micronutrients and phytochemicals purported to confer health benefits. The process of biofortification through traditional plant breeding has increased the protein, provitamin A carotenoid, and zinc contents of maize. The objective of this paper is to review the innovations developed and promoted to improve the nutritional profiles of maize and outcomes of the maize agro-food system.

Retention of Pro-Vitamin A Content in Products from New Biofortified Cassava Varieties

Plant breeding efforts in sub-Saharan Africa (SSA) have produced biofortified cassava with high carotenoid content to address vitamin A deficiencies (VAD). Since carotenoids in foods are easily depleted during processing, the retention of β-carotene in some newly released cassava varieties is under query. From four of these new varieties, two commonly consumed products (gari and its dough) were processed according to standard methods. Retention of β-carotene was then probed after applying fermentation periods of a day and three days. The possible contribution of the products to Vitamin A intake in children, adolescents, and women was also assessed. The concentration of β-carotene in fresh Cassava roots ranged from 5.32 to 7.81 µg/g. The percentage retention ranged from 14.4 to 29.3% and 10 to 21.7% in gari fermented for one and three days respectively. The impact of varietal difference and length of fermentation was significant on retention in the intermediate and final products (p < 0.001). When compared with dietary intake data, cooking biofortified gari into its dough reduced Vitamin A intake in most varieties. We conclude that processing Cassava into gari (especially its dough) could hinder the retention of β-carotene however some varieties have retention advantage over others irrespective of the initial concentration in their fresh roots.

Differentiation of maize breeding samples by β-carotene content

Plant carotenoids are important micronutrients in the diet of humans and animals, since they act as precursors for the synthesis of vitamin A in animal cells. The most effective precursor to the vitamin A biosynthesis is β-carotene. Increasing the β-carotene content in maize grain as an important feed and food crop is an urgent task for plant selection. The purpose of this work was to differentiate maize breeding samples from the Dnipro breeding program by the β-carotene content in mature grain. Maize grain of 18 inbreds harvested in 2015 and 5 inbreds harvested in 2016 was researched. Determination of β-carotene content in matured dry grain was carried out after petroleum ether extraction and ultra performance liquid chromatography (UPLC) in the mobile phase of methanol/acetonitrile. The β-carotene content in the grain of genotypes from the Dnipro breeding program was on average 1.020 mg/kg for inbreds grown in 2015, and 0.672 mg/kg for inbreds grown in 2016. These values correspond to the β-carotene content in the grain of the majority of genotypes from world breeding programs selected by methods of classical selection. The inbred DKV3262 with white grain had the smallest content of β-carotene (0.076 mg/kg), while the yellow-coloured line DKD9066 had the highest one (2.146 mg/kg). The variation in the grain β-carotene content in different years of maize cultivation was noted. Inbreds of flint and semident maize showed the general tendency to increase the β-carotene content in grain compared with dent ones. The distribution of the studied inbreds on germplasm types showed the significant variation of β-carotene content in grain and the incidence of relatively high values in all germplasms analyzed. Inbreds containing more than 1.5 mg of β-carotene per 1 kg of grain, DK239, DK206A, DK212, DKD9066 and DKE-1, are emphasized as promising for the selection to increase the content of valuable micronutrients.

Effect of soybean (Glycine max (L.) Merr.) flour inclusion on the nutritional properties and consumer preference of fritters for improved household nutrition

Diets in populations of most developing countries are often deficient in protein, carbohydrates, and fat, leading to protein-energy malnutrition (PEM). Diet-based strategies are the most promising approach for a sustainable control of PEM. This study aimed to investigate the effects of soy flour inclusion on the nutritional properties, consumer preference, purchase intent, and willingness to pay for wheat-based fritters. The proximate composition of both types of fritters was determined using standard methods, Consumer preference survey on organoleptic properties was carried out among 291 participants (93 men, 198 women) in Chipata, Katete, and Lundazi districts of Eastern Zambia. The soy-fortified fritters had significantly higher (p < 0.05) levels of ash, fat, amylose, crude fiber, and protein than the unfortified fritters. Protein, crude fiber, amylose, and ash contents of soy-fortified fritters were considerably increased by 55.5%, 18.9%, 98%, and 30.6%, respectively. The overall preference showed no significant difference (p > 0.05) between unfortified and soy-fortified fritters. A larger percentage of participants in Katete (38%) and Chipata (41%) preferred the soy-fortified fritters to the nonfortified one. In addition, no significant difference (p > 0.05) was also observed for intention to purchase between both types of fritters across the three locations. In conclusion, incorporating 20% soybean flour into fritters, which showed better nutrients quality, could be used to alleviate PEM among fritters consuming populations of developing countries, particularly in Sub-Saharan Africa.

Carotenoid and Tocochromanol Profiles during Kernel Development Make Consumption of Biofortified "Fresh" Maize an Option to Improve Micronutrient Nutrition

Biofortification is a strategy to reduce micronutrient malnutrition. The aim of this study was to investigate whether consumption of biofortified fresh maize can supply nutritionally meaningful amounts of provitamin A carotenoids (PVA), zinc, lysine, and tryptophan. The accumulation patterns for PVA and tocochromanol compounds in developing grain of 23 PVA hybrids was studied, and nutritionally meaningful amounts of those compounds were found in grain by milk stage, when fresh maize is eaten. The highest PVA and tocochromanol accumulation occurred by physiological maturity. The percent apparent retention in boiled fresh maize was 92%, 117%, 99%, and 66% for PVA, zinc, lysine, and tryptophan, respectively. Consumption of 0.5 to 2 ears of fresh maize daily could supply 33-62.2%, 11-24% and more than 85% of the estimated average requirement of PVA, tryptophan, and zinc, respectively. The results indicate that eating biofortified fresh maize can contribute to improved micronutrient nutrition.