Assessment of home-based processing methods to reduce the phytate content and phytate/zinc molar ratio of white maize (Zea mays)

Various methods of processing maize suitable for household use in rural Malawi, Central Africa, were investigated for their ability to reduce its phytate content and phytate/zinc molar ratio. These methods included fermentation, germination, and soaking. Penta- and hexainositol phosphates were measured by HPLC, and zinc was measured by atomic absorption spectrophotometry. Natural lactic fermentation of maize flour slurries resulted in 88% phytate retention compared to unprocessed, unrefined maize flour porridges, whereas lower phytate retention was observed when a starter culture (61%) or germinated flour (71%) was also used. Fermentation of cooked maize flour porridges with germinated flour added resulted in 54-85% retention of phytate compared to controls. Soaking maize flour or pounded maize and decanting excess water resulted in 43 and 49% retention of phytate, respectively. The latter soaking procedures were simple and effective and were suitable for household use in rural Malawian communities.     

Retention and bioaccessibility of β-carotene in blended foods containing orange-fleshed sweet potato flour

The retention and bioaccessibility of β-carotene (BC) in blended foods made with part orange-fleshed sweet potato (OFSP) flour (30%) were examined. Chapatis and porridges were prepared by local processors under field conditions (FC) in Uganda (n=10). While the retention of all-trans-BC in porridges (69 to 93%) and chapatis (70 to 97%) varied between the processors, there was no overall difference between the two products and this was probably because of the variability in FC. BC retention in mandazis was similar to that of chapatis and porridges. Processing in FC significantly increased the amount of cis-isomers, in particular 13-cis-BC. The bioaccessibility of the BC as measured by their transfer into micelles was evaluated using an in vitro digestion procedure in various OFSP-derived products. After in vitro digestion, the percentage of micellarized all-trans-BC was greater in products cooked with oil, chapati (73%) and mandazi (49%), as compared with the boiled ones, porridge (16%) and pure?ed from boiled root (10%). In all the products, the incorporation into micelles for 13-cis-BC was significantly higher to that of all-trans-BC. When taking into account the bioaccessibility of all-trans-BC and 13-cis-BC isomer, an edible portion of porridge (one mug), boiled root (half a root), mandazis (two), or chapati (one) could provide a significant part of the daily vitamin A requirements of a child under 6 years (respectively 20, 46, 75, or 100%). These data support the promotion/consumption of locally cooked OFSP food products to tackle vitamin A deficiency in sub-Saharan Africa.     

Carotenoid bioaccessibility from whole grain and degermed maize meal products

Although yellow maize (Zea mays) fractions and products are a source of dietary carotenoids, only limited information is available on the bioavailability of these pigments from maize-based foods. To better understand the distribution and bioavailability of carotenoid pigments from yellow maize (Z. mays) products, commercial milled maize fractions were screened for carotenoid content as were model foods including extruded puff, bread, and wet cooked porridge. Carotenoid content of maize fractions ranged from a low of 1.77-6.50 mg/kg in yellow maize bran (YCB) to 12.04-17.94 mg/kg in yellow corn meal (YCM). Lutein and zeaxanthin were major carotenoid species in maize milled fractions, accounting for approximately 70% of total carotenoid content. Following screening, carotenoid bioaccessibility was assessed from model foods using a simulated three-stage in vitro digestion process designed to measure transfer of carotenoids from the food matrix to bile salt lipid micelles (micellarization). Micellarization efficiency of xanthophylls was similar from YCM extruded puff and bread (63 and 69%), but lower from YCM porridge (48%). Xanthophyll micellarization from whole yellow corn meal (WYCM) products was highest in bread (85%) and similar in extruded puff and porridge (46 and 47%). For extruded puffs and breads, beta-carotene micellarization was 10-23%, but higher in porridge (40-63%), indicating that wet cooking may positively influence bioaccessibility of apolar carotenes. The results suggest that maize-based food products are good dietary sources of bioaccessible carotenoids and that specific food preparation methods may influence the relative bioaccessibility of individual carotenoid species.     

Condensed Tannins in Traditional Wet‐Cooked and Modern Extrusion‐Cooked Sorghum Porridges

The profile and quantities of condensed tannins (CT) in foods are affected by processing due to their highly reactive nature, which may affect their antioxidant activity and the nutritional value of the foods. The objective was to compare the quantity and profile of condensed tannins in traditional wet‐cooked and modern ready‐to‐eat extrusion‐cooked sorghum porridges. CT were analyzed using normal‐phase HPLC with fluorescence detection and their content was compared to CT and total phenols determined with standard colorimetric assays. Both the traditionally prepared and instant porridges had significantly reduced CT polymers (DP > 8), with retentions of 38 and 9%, respectively, of the CT present in the whole grain. Oligomer (DP 2–8) and monomer (DP 1) contents in traditional porridges were not significantly different from those of grain. In extruded porridges, the oligomers were reduced and the monomer content was increased. The extractable CT oligomers and monomers in the extrusion‐cooked sorghum porridges may be more biologically available because extrusion appears to increase their availability.     

Anaemia, iron status and vitamin A deficiency among adolescent refugees in Kenya and Nepal

OBJECTIVE: To investigate the prevalence of anaemia (haemoglobin<11.0 to 13.0 g dl(-1) depending on age and sex group), iron deficiency (transferrin receptor concentration>8.3 microg ml(-1)) and vitamin A deficiency (serum retinol <0.7 micromol l(-1)) in adolescent refugees. DESIGN: Cross-sectional surveys. SETTING: Kakuma refugee camp in Kenya and seven refugee camps in Nepal. SUBJECTS: Adolescent refugee residents in these camps. RESULTS: Anaemia was present in 46% (95% confidence interval (CI): 42-51) of adolescents in Kenya and in 24% (95% CI: 20-28) of adolescents in Nepal. The sensitivity of palmar pallor in detecting anaemia was 21%. In addition, 43% (95% CI: 36-50) and 53% (95% CI: 46-61) of adolescents in Kenya and Nepal, respectively, had iron deficiency. In both surveys, anaemia occurred more commonly among adolescents with iron deficiency. Vitamin A deficiency was found in 15% (95% CI: 10-20) of adolescents in Kenya and 30% (95% CI: 24-37) of adolescents in Nepal. Night blindness was not more common in adolescents with vitamin A deficiency than in those without vitamin A deficiency. In Kenya, one of the seven adolescents with Bitot's spots had vitamin A deficiency. CONCLUSIONS: Anaemia, iron deficiency and vitamin A deficiency are common among adolescents in refugee populations. Such adolescents need to increase intakes of these nutrients; however, the lack of routine access makes programmes targeting adolescents difficult. Adolescent refugees should be considered for assessment along with other at-risk groups in displaced populations.     

Stability of Vitamin E in Wheat Flour and Whole Wheat Flour During Storage

The stability of vitamin E during 297 days of storage of wheat flour and whole wheat flour ground on a stone mill or a roller mill, respectively, were studied. One day after milling, the total content of vitamin E, expressed in vitamin E equivalents (α‐TE), was 18.7 α‐TE and 10.8 α‐TE for stone‐milled and roller‐milled wheat flour, respectively. The difference in total vitamin E content was primarily due to the absence of the germ and bran fractions in the roller‐milled flour. The total loss of vitamin E during storage was 24% for stone‐milled wheat flour but 50% for roller‐milled wheat flour. These results indicate that vitamin E, which is present in high amounts in wheat germ, functions as an antioxidant in the stone‐milled wheat flour. Hexanal formation showed that lipid oxidation in roller‐milled flour occurred just after milling, whereas the formation of hexanal in the germ fraction displayed a lack period of 22 days, confirming that vitamin E functions as an effective antioxidant in the wheat germ. Results showed no significant difference in total loss of vitamin E for stone‐milled and roller‐milled whole wheat flour. Total loss after 297 days of storage for both milling methods was ≈32%.     

Quality and Fortificant Retention of Rice Noodles as Affected by Flour Particle Size

Rice noodles, which are widely consumed noodles in Southeast Asia, were evaluated as a potential carrier for fortificants such as vitamin A, folic acid, and iron. Because flour particle size was found to affect the noodle properties, this study was conducted to investigate the effect of five different particle sizes (≤63, 80, 100, 125, and 140 µm) of dry‐milled rice flour on the cooking quality, microstructure, texture, and sensory characteristics of the rice noodles. The retention of fortificant in the noodles at every stage of processing as affected by the flour particle size was also determined. It was found that the rice noodles produced from flour with the smallest particle size studied (≤63 µm) had the best quality and were the most liked by the consumers. In addition, the noodles had the most compact and regular structure, which could be attributed to having the most severely gelatinized starch. This starch would have caused the least leaching of the fortificant into the surrounding water during the boiling stage of the rice noodle processing. Retention of iron in the cooked fortified rice noodles prepared from flour with the smallest particle size was high at around 87%, whereas that of vitamin A and folic acid were below 15%. Because the losses of the fortificant from the rice noodles were mostly owing to the boiling process, further improvements of the rice noodle processing conditions are required for reduction of the vitamin losses.     

The xanthophyll composition of biofortified maize (Zea mays Sp.) does not influence the bioefficacy of provitamin a carotenoids in Mongolian gerbils (Meriones unguiculatus)

Maize has been targeted for biofortification with provitamin A carotenoids through traditional breeding. Two studies were conducted in gerbils to evaluate factors that may affect provitamin A activity. Maize diets had equal theoretical concentrations of vitamin A (VA) assuming 100% bioefficacy. Study 1 ( n = 57) varied the ratio of beta-cryptoxanthin and beta-carotene but maintained the same theoretical VA. Study 2 ( n = 67) varied lutein and zeaxanthin. Other treatments were oil, VA, or beta-carotene doses. Serum and livers were analyzed for VA and carotenoids. In study 1, total liver VA did not differ among the maize groups. In study 2, total liver VA of the VA and maize groups were higher than controls ( P < 0.05). Conversion factors were 2.1-3.3 mug beta-carotene equivalents to 1 mug retinol. Twice the molar amount of beta-cryptoxanthin was as efficacious as beta-carotene and the proportion of beta-cryptoxanthin or xanthophylls did not appreciably change the VA value of biofortified maize.     

Low α-Amylase Starch Digestibility of Cooked Sorghum Flours and the Effect of Protein

The comparably low starch digestibility of cooked sorghum flours was studied with reference to normal maize. Four sorghum cultivars that represent different types of endosperm were used. Starch digestibilities of 4% cooked sorghum flour suspensions, measured as reducing sugars liberated following α-amylase digestion, were 15–25% lower than for cooked maize flour, but there were no differences among the cooked pure starches. After the flours were predigested with pepsin to remove some proteins, the starch digestibility of cooked sorghum flours increased 7–14%, while there was only 2% increase in normal maize; however, there was no effect of pepsin treatment on starch digestibility if the flours were first cooked and then digested. After cooking with reducing agent, 100 mM sodium metabisulfite, starch digestibility of sorghum flours increased significantly while no significant effect was observed for maize. Also, starch solubility of sorghum flours at 85 and 100°C was lower than in maize, and sodium metabisulfite increased solubility much more in sorghum than in maize. Differential scanning calorimetry results of the flour residue after α-amylase digestion did not show any peaks over a temperature range of 20–120°C, indicating that sorghum starches had all undergone gelatinization. These findings indicate that the protein in cooked sorghum flour pastes plays an important role in making a slowly digesting starch.     

Sequential in vitro pepsin digestion of uncooked and cooked sorghum and maize samples

An in vitro protein digestion study, using pepsin, was carried out in uncooked and cooked sorghum and maize flour samples. The digestibility values from the uncooked samples showed that sorghum presents digestibility values similar to those of maize. In the case of the cooked samples, it was found that a wet cooking procedure promotes a decrease in sorghum protein digestibility when compared to maize. Electrophoresis was used to follow the in vitro pepsin sequential digestion procedure, and infrared spectroscopy was applied to establish its efficiency. SDS-PAGE results showed that both uncooked samples (sorghum and maize) behave in a similar way. The wet cooking procedure increases the amount of high molecular weight aggregates and promotes the appearance of two nonreducible and nondigestible 45 and 47 kDa proteins. These two protein fractions are directly related to the loss of digestibility. It was also shown that in cooked sorghum the monomers (gamma-, alpha-, and beta-) are more resistant to digestion than the corresponding uncooked samples.     

Maternal micronutrient status and decreased growth of Zambian infants born during and after the maize price increases resulting from the southern African drought of 2001-2002

OBJECTIVE: To investigate the effects on maternal micronutrient status and infant growth of the increased maize prices that resulted from the southern African drought of 2001-2002. DESIGN: Longitudinal cohort study. SETTING: A maternal and child health clinic in Lusaka, Zambia. SUBJECTS: Maternal and infant health and nutrition data and maternal plasma were being collected for a study of breast-feeding and postpartum health. Samples and data were analysed according to whether they were collected before (June to December 2001), during (January 2002 to April 2003) or after (May 2003 to January 2004) the period of increased maize price. Season and maternal HIV status were controlled for in analyses. RESULTS: Maize price increases were associated with decreased maternal plasma vitamin A during pregnancy (P = 0.028) and vitamin E postpartum (P = 0.042), with the lowest values among samples collected after May 2003 (vitamin A: 0.96 micromol l(-1), 95% confidence interval (CI) 0.84-1.09, n = 38; vitamin E: 30.8 micromol mmol(-1) triglycerides, 95% CI 27.2-34.8, n = 64) compared with before January 2002 (vitamin A: 1.03 micromol l(-1), 95% CI 0.93-1.12, n = 104; vitamin E: 38.9 micromol mmol(-1) triglycerides, 95% CI 34.5-43.8, n = 47). There were no significant effects of sampling date on maternal weight, haemoglobin or acute-phase proteins and only marginal effects on infant weight. Infant length at 6 and 16 weeks of age decreased progressively throughout the study (P-values for time of data collection were 0.51 at birth, 0.051 at 6 weeks and 0.026 at 16 weeks). CONCLUSIONS: The results show modest effects of the maize price increases on maternal micronutrient status. The most serious consequence of the price increases is likely to be the increased stunting among infants whose mothers experienced high maize prices while pregnant. During periods of food shortages it might be advisable to provide micronutrient supplements even to those who are less food-insecure.     

Effect of beta-carotene and vitamin E on oxidative stability in leg meat of broilers fed different supplemental fats

The objectives of this study were to investigate the effects of dietary fat (6% lard and sunflower and olive oil) and supplementation of alpha-tocopheryl acetate or beta-carotene on vitamin E content and lipid oxidation in raw, cooked, and chilled-stored broiler leg meat. Vitamin E increased its tissue level, reducing lipid oxidation. The oxidative stability of leg meat tended to decrease with dietary sunflower oil. Effects of beta-carotene on vitamin E levels and oxidation depended on dietary fat and its concentration in feed, decreasing vitamin E, mainly at 50 ppm. beta-Carotene at 15 ppm acted as antioxidant in fresh and cooked meat in the sunflower and olive oil diets. However, in stored meat, beta-carotene at 50 ppm increased TBARS, probably due to a decrease in vitamin E content and direct prooxidant effects per se. It is suggested that the antioxidant effect of beta-carotene requires the presence of vitamin E in tissues.     

Pearling of hull-less barley: product composition and gel color of pearled barley flours as affected by the degree of pearling

Barley grains from two hull-less varieties, Phoenix and Candle, were pearled to various degrees (10-80%). The composition (starch, protein, beta-glucan, lipid, and ash) of pearled grain (PG) and pearling flour (PF) was determined. Effect of pearling on Hunter L, a, and b color parameters of uncooked and cooked (gel) barley flour (milled from PG) was investigated over a 3 day storage at 4 degrees C.     

调质大米半干法磨粉制备鲜米粉及其品质测定

为考察半干法磨粉对鲜米粉品质的影响,该研究选用旋风磨和布勒磨对调质后含水率为28%和30%的大米进行磨粉,分析大米粉的白度、凝胶特性及糊化特性,对加工鲜米粉的质构特性、蒸煮特性和感官品质进行了分析。结果显示:调质大米可以减小磨粉仪器机械力和热能对大米粉品质的破坏,其中调质大米经布勒磨粉碎后的白度显著高于湿磨粉白度(P0.05);旋风磨含水率为30%调质粉的凝胶硬度最大为3.45 N/cm2,与湿磨粉的无显著差异(P0.05);2种调质粉相比于湿磨粉其崩解值较小,其中布勒磨含水率为30%调质粉回生程度较低,与湿磨粉无显著差异(P0.05)。对于鲜米粉的品质,筛选得到的旋风磨含水率为30%鲜米粉的硬度为35.10 N/cm2,弹性为0.97,较湿磨米粉更柔软弹滑,感官评价总分和蒸煮特性与湿磨米粉无显著差异。以上结果表明,含水率为30%的大米经旋风磨粉碎后能够制得与湿法磨浆相媲美的鲜米粉,可为解决湿磨法废水量大、产品得率低等问题提供参考。     

Cooking,Roasting, and Fermentation of Chickpeas,Lentils, Peas,and Soybeans for Fortification of Leavened Bread

The effects of cooking, roasting, and fermentation on the composition and protein properties of grain legumes and the characteristics of dough and bread incorporated with legume flours were determined to identify an appropriate pretreatment. Oligosaccharide content of legumes was reduced by 76.2–96.9% by fermentation, 44.0–64.0% by roasting, and 28.4–70.1% by cooking. Cooking and roasting decreased protein solubility but improved in vitro protein digestibility. Mixograph absorption of wheat and legume flour blends increased from 50–52% for raw legumes to 68–76, 62–64, and 74–80% for cooked, roasted, and fermented ones, respectively. Bread dough with cooked or roasted legume flour was less sticky than that with raw or fermented legume flour. Loaf volume of bread baked from wheat and raw or roasted legume flour blends with or without gluten addition was consistently highest for chickpeas, less for peas and lentils, and lowest for soybeans. Roasted legume flour exhibited more appealing aroma and greater loaf volume of bread than cooked legume flour, and it appears to be the most appropriate preprocessing method for incorporation into bread.     

Fermented pigeon pea (Cajanus cajan) ingredients in pasta products

Pigeon pea (Cajanus cajan var. aroíto) seeds were fermented in order to remove antinutritional factors and to obtain functional legume flour to be used as pasta ingredients. Fermentation brought about a drastic reduction of alpha-galactosides (82%), phytic acid (48%), and trypsin inhibitor activity (39%). Fermented legume flours presented a notable increase of fat and total soluble available carbohydrates, a slight decrease of protein, dietary fiber, calcium, vitamin B2, vitamin E, and total antioxidant capacity, and a decrease of soluble dietary fiber, Na, K, Mg, and Zn contents. No changes were observed in the level of starch and tannins as a consequence of fermentation. The fermented flour was used as an ingredient to make pasta products in a proportion of 5, 10, and 12%. The supplemented pasta products obtained had longer cooking times, higher cooking water absorptions, higher cooking loss, and higher protein loss in water than control pasta (100% semolina). From sensory evaluations, fortified pasta with 5 and 10% fermented pigeon pea flour had an acceptability score similar to control pasta. Pasta supplemented with 10% fermented pigeon pea flour presented higher levels of protein, fat, dietary fiber, mineral, vitamin E, and Trolox equivalent antioxidant capacity than 100% semolina pasta and similar vitamins B1 and B2 contents. Protein efficiency ratios and true protein digestibility improved (73 and 6%, respectively) after supplementation with 10% fermented pigeon pea flour; therefore, the nutritional value was enhanced.     

Lipid-soluble antioxidants status and some of its socio-economic determinants among pregnant Ethiopians at the third trimester

OBJECTIVE: To determine the serum levels of three lipid-soluble antioxidants (retinol, beta-carotene and alpha-tocopherol) in pregnant women attending an antenatal clinic (ANC) in Gondar, Ethiopia. DESIGN: A cross-sectional study involving laboratory determination of serum levels of retinol, alpha-tocopherol and beta-carotene using high-performance liquid chromatography and questionnaire-based assessment of socio-economic status. SETTING: ANC of a university teaching hospital. SUBJECTS: Three hundred and twenty-two healthy pregnant women in their third trimester, who attended the ANC. RESULTS: Mean serum levels of retinol, alpha-tocopherol and beta-carotene were found to be 1.23+/-0.5, 25.5+/-0.9 and 0.21+/-0.09 micromol l(-1), respectively. The prevalence of vitamin A deficiency (<1.05 micromol l(-1)) among pregnant women was 38.5%. Women having low retinol (vitamin A) levels were highly likely to live in earth-floored and mud-walled houses, and less likely to own a house and to have a latrine. CONCLUSION: The study shows that serum levels of lipid-soluble antioxidants were low among ANC attendees in northern Ethiopia. It also indicates that some socio-economic factors (such as poor housing standard) are associated with vitamin A deficiency.     

Alkaline‐Carbonate Noodles from Hard Winter Wheat Flours Varying in Protein,Swelling Power,and Polyphenol Oxidase Activity

The effects of wheat protein and starch on yellow‐alkaline noodles have not been fully clarified. Twenty‐four hard winter wheats with varying protein, hot‐water swelling power (SP₉₅), and polyphenol oxidase (PPO) activity were milled into long‐patent and short‐patent flours. Protein, SP₉₅, and PPO activity in the 48 flours were 8.2–12.9%, 16.2–24.1 g/g, and 80–157 ΔA₄₈₀/mg of protein/min, respectively. Lightness of raw noodles declined with increasing protein and PPO levels but yellowness decreased and then increased. Tensile force to break the cooked noodles was positively correlated with SP₉₅ and protein. Compression (50%) force of noodles made from flour with high SP₉₅ ≈21 g/g, averaged ≈20% below those made from low SP₉₅ ≈17 g/g of flour. Compression force was measured in the long dimension of a single noodle strand using a rectangular probe. The instrumental measurements suggest that alkaline noodles made from a single‐null partial‐waxy wheat with medium SP₉₅ ≈19.9 g/g will have a tender bite and a cohesive texture compared with those from a low SP₉₅ wheat with a hard bite and fracturable texture. Furthermore, alkaline noodles from a double‐null partial‐waxy wheat with high SP₉₅ will have an extra soft bite unless flour protein is above ≈12.5%. Hard‐white, dual‐purpose wheat should have a low level of PPO and, depending on the preferred noodle‐eating texture, a low to medium SP₉₅ level. Such wheats with medium protein levels (11–12%) are well suited for alkaline noodles because of improved color and surface smoothness, whereas the same wheats with 12–13% protein are well suited for bread. Wheats with medium SP₉₅ also reduce cooking loss and increase cooked yield.     

Study on furundu, a traditional Sudanese fermented roselle (Hibiscus sabdariffa L.) seed: effect on in vitro protein digestibility, chemical composition, and functional properties of the total proteins

Furundu, a meat substitute, is traditionally prepared by cooking the karkade (Hibiscus sabdariffa L.) seed and then fermenting it for 9 days. Physicochemical and functional properties of raw and cooked seed and of furundu ferments were analyzed. Furundu preparation resulted in significant changes in karkade seed major nutrients. Total polyphenols and phytic acid were also reduced. The increase in total acidity and fat acidity coupled with a decrease in pH indicates microbial hydrolysis of the major nutrients; proteins, carbohydrates, and fats. In vitro digestibility of the seed proteins reached the maximum value (82.7%) at the sixth day of fermentation, but thereafter it significantly decreased. The effect of furundu preparation on N solubility profiles and functional properties, such as emulsification and foaming properties and other related parameters, is investigated in water and in 1 M NaCl extracts from defatted flour samples. The results show that cooking followed by fermentation affects proteins solubility in water and 1 M NaCl. The foaming capacity (FC) from the flour of raw seed decreased as a result of cooking. Fermentation for 9 days significantly increased the FC of the cooked seed, restoring the inherent value. Foam from fermented samples collapsed more rapidly during a period of 120 min as compared to the foam from raw and cooked karkade seeds; stability in 1 M NaCl was lower as compared to those in water. In water, the emulsion stability (ES) from the fermented samples was significantly higher than that of the raw seed flour. Addition of 1 M NaCl significantly decreased the ES of the fermented samples.