Effect of natural fermentation on phytate and polyphenolic content and in-vitro digestibility of starch and protein of pearl millet (Pennisetum typhoideum)

Natural fermentation at 20, 25 and 30°C for 72 h brought about a significant reduction in phytic acid content of pearl millet (Pennisetum typhoideum Rich) flour. The phytate content was almost eliminted in the flour fermented at 30°C. An increase in polyphenol content of fermented flour was noticed, the higher the temperature of fermentation the greater was the increase in polyphenol content of pearl millet. An improvement in starch as well as protein digestibility (in vitro) was noticed at all the temperatures of natural fermentation, the highest being at 30°C.     

Effect of malting and fermentation on antinutrients,and total and extractable minerals of high and low phytate corn genotypes

Two corn genotypes, Var‐113 (high phytate) and TL‐98B‐6225‐9 × TL617 (low phytate), were germinated for 6 days. The germinated grains were dried and milled. A mixture of 5% malt and 95% corn flour was fermented for 14 days. Phytic acid and polyphenol contents and hydrochloric acid (HCl) extractability of minerals from the fermented flours were determined at the intervals of 2 days during fermentation. Phytic acid and polyphenol contents decreased significantly (P ≤ 0.05) with an increase in fermentation time, with a concomitant increase in HCl‐extractable minerals. For both genotypes, the major mineral content was increased, while that of trace minerals was increased but at slow rate with fermentation time. When the grains were fermented for 14 days, TL‐98B‐6225‐9 × TL617 genotype had higher extractable calcium and Var‐113 had higher extractable phosphorus, whereas iron and manganese recorded high extractability levels in Var‐113. There was good correlation between phytate and polyphenol level reduction and the increment in extractable minerals with fermentation time.     

Lactic Fermentation of Non-Tannin and High-Tannin Cereals: Effects on In Vitro Estimation of Iron Availability and Phytate Hydrolysis

The effect on iron availability estimated in vitro and phytate hydrolysis was investigated in non-tannin and high-tannin cereals, lactic fermented as flour/water slurries or gruels. A natural starter culture initiated fermentation and addition of germinated flour and phytase in the fermentation process was tested. Lactic fermentation of nontannin cereals with added flour germinated sorghum seeds or wheat phytase increased iron solubility from about 4% up to 9 and 50%, respectively. Soaking flour in water before adding starter culture had a similar effect. The increase in soluble iron was strongly related to enzymatic deeradation of phytate (p<0.001). The reduction of inositol hexa- and pentaphosphates was about 50% with added germinated flour. Reduction was > 90% after soaking the flour prior to fermentation and almost complete with 50 mg phytase added. High-tannin cereals showed a minor increase in soluble iron after fermentation, ascribed to the inhibitory effect of tannins (both on iron solubility and on enzymatic hydrolysis of phytate). Lactic-fermented cereal foods have a potential in developing countries to improve iron nutrition.     

Effect of germination and probiotic fermentation on nutrient composition of barley based food mixtures

Food mixtures formulated from non-germinated and germinated barley flour, whey powder and tomato pulp (2:1:1w/w) were autoclaved, cooled and fermented with 5% Lactobacillus acidophilus curd (10⁶ cells/ml) at 37 °C for 12 h. The cell count was found significantly higher (8.88 cfu/g) in the fermented food mixture formulated from germinated flour as compared to the non-germinated barley based food mixture. A significant drop in pH with corresponding increase in titratable acidity was found in the germinated barley flour based food mixture. Processing treatments like germination, autoclaving and probiotic fermentation did not bring about any significant change in ash and fat contents, but significant decrease was noticed in crude protein, crude fibre, starch, total and insoluble dietary fibre contents. The combined processing caused significant improvement in reducing sugar, thiamine, niacin, lysine and soluble dietary fibre contents of barley based food mixtures. In conclusion, a combination of germination and fermentation is a potential process for enhancing the nutritional quality of food mixtures based on coarse cereals.     

Physicochemical property changes in germinated brown rice flour from different storage periods of paddy rice

This study revealed that the storage duration (2, 4, 6, 8, 10 and 12 months) of paddy rice and pH (3 and 6.8) of steeping water during germination were significantly influenced the physicochemical properties of germinated brown rice flour (GBRF). GBRF obtained at pH 3 vs. 6.8 provided the highest both reducing sugar content and free gamma‐aminobutyric acid (GABA) content (99.8 vs. 54.2 mg per 100 g flour respectively) as the paddy rice was stored for 8 months. The peak viscosity of GBRF obtained at pH 3 and 6.8 exhibited the lower values than that of non‐GBRF throughout the storage. From the principal component analysis, reducing sugar had a positive correlation with α‐amylase activity whereas a negative correlation was found with peak viscosity. GBRF from paddy rice stored for 8 months and germinated at pH 3 possessed the highest free GABA content, 50 times of the non‐GBRF, which can be further utilised in functional and healthy foods.     

Seed treatments affect functional and antinutritional properties of amaranth flours

The effects of seed treatments, including cooking, popping germination and flour air classification, on the functional properties and antinutritional factors of Amaranthus caudatus and Amaranthus cruentus seeds were studied. Thermal treatments increased the water absorption with a maximum value of 5.1 and 6.3 g g⁻¹ in flour of popped seeds of both species. Generally, fat absorption increased after the treatments. Air classification and germination followed by drying at low temperature increased the foam stability of the flours, while thermal treatment and germination followed by drying at higher temperatures reduced the foam stability. All treatments except air classification decreased the emulsion stability. Also, all treatments except germination followed by drying at 30 °C increased the flour dispersibility, whereas the soluble nitrogen index was increased in the germinated seed flours and decreased in thermal treated seeds and air‐classified flours. Air classification increased the contents of phenolic compounds and phytate and decreased the contents of enzyme inhibitors, whereas the thermal treatments reduced the contents of phenolic compounds, phytate and enzyme inhibitors to a greater extent for cooking than for popping. Germination followed by drying reduced the level of phenolic compounds, phytate and enzyme inhibitors. Copyright © 2006 Society of Chemical Industry     

富铬发芽糙米粉性质分析及其在馒头中的应用研究

目的 探究富铬发芽对糙米粉性质的影响及其应用特性研究。方法 通过单因素实验明确发芽糙米中有机铬最佳富集工艺, 对普通糙米粉、普通发芽糙米粉、富铬发芽糙米粉的热力学性质、结晶结构、短程有序结构、水解氨基酸总含量及表面微观结构进行比较。将富铬发芽糙米粉应用于馒头制作, 并对糙米馒头的质构分析、感官评分进行研究。结果 糙米在浸泡时间12 h、发芽温度30℃、三氯化铬溶液质量浓度为80 mg/L时, 有机铬含量达到最高0.266mg/kg, 此时有机铬转化率为50.7%。富铬发芽糙米粉与普通糙米粉相比, 糊化焓值升高14.49%。水解氨基酸总含量升高3.37%。在小麦粉中添加20%比例富铬发芽糙米粉使馒头的硬度升高52.30%, 胶黏性升高30.64%, 咀嚼性升高32.21%, 弹性降低32.30%。此时糙米馒头的感官评分最高, 为87.7分, 最易被人们接受。结论 富铬发芽过程并未改变糙米粉的理化性质, 20%糙米粉添加比例接受度最高, 这可为富铬发芽糙米粉的应用提供参考依据。     

Natural fermentation of lentils

Lentil (Lens culinaris var. vulgaris) flour was naturally fermented for 4 days at different temperatures (28°C, 35°C and 42°C) and concentrations (79 g/1, 150 g/1 and 221 g/1). Samples were analysed to establish the changes of total protein content and in vitro protein digestibility, trypsin inhibitor activity (TIA) and phenolic compound content during natural fermentation of lentils. The preparation of lentil flour suspensions to be fermented caused a slight increase in total protein and in vitro protein digestibility content, a decrease of TIA and a sharp decrease the tannin/catechin ratio. During the whole fermentation procedure, the minimum initial lentil concentration and temperature used (79 g/1, 28°C) achieved the maximum protein content and the lowest tannin/catechin ratio. The TIA was more affected by temperature than by concentration, and a 62.5% reduction was observed at 42°C and 79 g/1.     

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

Effect of malt pretreatment on phytate and tannin level of two sorghum (Sorghum bicolor) cultivars

The seeds of two cultivars of Sudanese sorghum (Sorghum bicolor), namely Wad Ahmed and Tabat, were germinated for 4 days to obtain 1‐, 2‐ and 4‐day‐old malts. Sorghum malt (5% and 10%) was added to sorghum flour. The mixtures were incubated at 30 °C with shaking for 30, 60, 90 and 120 min. Malting loss was very slight for both cultivars and for all incubation periods. Phytic acid and tannin contents were assayed for all treatments. The results revealed that phytate and tannin contents were significantly (P ≤ 0.05) reduced when sorghum flour was pretreated with malt. When a mixture containing 10%, 4‐day‐old malt and sorghum flour was incubated for 120 min, it significantly (P ≤ 0.05) reduced phytate and tannin contents by 92% and 98%, respectively, for Wad Ahmed cultivar, while for Tabat they were reduced by 93% and 96%, respectively. The rate of reduction of phytate and tannin content increased with incubation time and malt age and concentration.     

Natural fermentation of lentils Influence of time, temperature and flour concentration on the kinetics of thiamin, riboflavin and niacin

Lentils (Lens culinaris, var. vulgaris cultivar Magda-20) were naturally fermented for 96 h at different lentil flour concentrations (79, 150 and 221 g/l) and temperatures (28, 35 and 42°C). During fermentation, samples were taken at 24-h intervals and the changes in thiamin (vitamin B₁), riboflavin (vitamin B₂) and total and available niacin (vitamin B₃) were investigated. Preparation of the lentil flour suspension to be fermented (i.e. the process of mixing the flour and sterilized tap water) caused an increase of the available niacin content in all batches, while changes in thiamin and riboflavin content were related to the conditions in which the preparation of the suspensions was carried out. The whole natural fermentation process (from the raw state to after 96 h of fermentation), either did not affect or produced a slight decrease in the thiamin content of lentils. In contrast, riboflavin, available niacin and total niacin contents increased throughout the 96 h period, which ended with a 35?–?82% increase of riboflavin, a 24?–?91% increase of available niacin and a 20?–?58% increase of total niacin. The temperature during the fermentation procedure had significant effect on the levels of thiamin and riboflavin in fermented lentils. To obtain lentil flours with an improved amount of riboflavin and available niacin with a minimum loss of thiamin, the natural fermentation of lentils should be carried out for 96 h at 42°C and with a lentil flour concentration of 221 g/l.     

Effect of fermentation on HCl extractability of minerals in Rabadi-an indigenous fermented food of India

Pearl millet flour/buttermilk mixture was fermented at 35, 40, 45 and 50°C for 3, 6 or 9 h to prepare rabadi. Fermentation at all temperatures decreased phytate P, increased non-phytate P and increased HCl extractability of P, Ca, Fe, Zn and Cu; the extractability increased with an increase in the period of fermentation. The largest improvement was seen in extractability of Fe, followed by that of P, Zn, Ca and Cu. Mn extractability did not change as a result of fermentation.     

Tempeh Prepared from Germinated Soybeans

The oligosaccharide (sucrose, raffinose and stachyose) and phytate contents of soybeans were reduced by 12–24 hr germination. The tempeh fermentation of the germinated soybeans caused a further decrease in oligosaccharide, phytate and fat contents. As a result of these decreases, the proportion of protein (% N × 6.25) in the tempeh solids rose. The soybean lectins were not affected by the germination process but were inactivated during the preparation of tempeh. The adjusted protein efficiency ratio for regular tempeh was 2.19 vs 2.26 for tempeh prepared from germinated soybeans. The difference, however, was not statistically significant (n = 10 rats).     

Biological activities of fermented soybean paste (Doenjang) prepared using germinated soybeans and germinated black soybeans during fermentation

To produce doenjang with enhanced biological activities, doenjang was prepared by fermenting regular soybeans (RS), germinated soybeans (GS), and germinated black soybeans (GBS) for 90 days. The isoflavone contents in GS and GBS-doenjang were slightly higher than in RS-doenjang in the early stage of fermentation. The DPPH radical scavenging activity of GBS-doenjang was highest at 70.00% after 30 days of fermentation. The angiotensin-converting enzyme (ACE) inhibiting effects increased as the fermentation period progressed, and were significantly (p<0.05) higher in GBS-doenjang (58.69%) than in other preparations after 75 days of fermentation. The greatest fibrinolytic activities were 127.59 and 100.00% in nontreated GBS-doenjang and GBS-doenjang treated for 30 min at 55°C, respectively. There were significant (p<0.05) correlations between the total isoflavone content and the antioxidant activity (0.779) and between the isoflavone content and the ACE activity-inhibiting effects (0.669). GBS-doenjang exhibited greater antioxidant activities, ACE-inhibition, and fibrinolytic activities than RS and GS-doenjang.     

Content of phytic acid and HCl-extractability of calcium,phosphorus and iron as affected by various domestic processing and cooking methods

ICPL-87, the high yielding cultivar of pigeon pea (Cajanus cajan) released by ICRISAT (International Crop Research Institute for Semi-Arid Tropics), India was subjected to various domestic processing and cooking methods, i.e. soaking (6, 12, 18 h, 30°C), soaking (12 h) and dehulling, ordinary as well as pressure cooking and germination (24, 36 and 48 h, 30°C). The unprocessed seeds of this variety contained considerable amounts of phytic acid, (857 mg per 100 g). This was reduced significantly (P<0.05) by 6–28%, 30%, 4–32%, 4–36%, 35–45% in soaked, soaked-dehulled, ordinary as well as pressure cooked and germinated seeds, respectively. Except for soaking and dehulling, the remaining processing and cooking methods did not lower the contents of total calcium, phosphorus and iron. HCl-extractability of these dietary essential minerals, an index of their bioavailability, was enhanced significantly when the pigeon pea seeds were processed and cooked, possibly due to reduction in phytate content, which is known to chelate the minerals. A significant and negative correlation between the phytic acid and HCl-extractability of minerals further strengthens these findings.     

Effect of germination time on alpha-amylase production and viscosity of maize porridge

Maize grain was steeped, germinated (0 to 7 days), dried and milled. Porridge (15% dry matter) was made by adding 1:5, 1:2 or 1:1 germinated flour to ungerminated flour. A smooth batter was made prior to heating in a boiling water bath for 1 h. A second batch was left for a respite period of 1 h at 40 °C, before boiling. The viscosity was measured after cooling. Correlation was found between germination time, alpha-amylase content and porridge viscosity. Increasing germination time led to increased production of alpha-amylase, and corresponded to reduced viscosity. Germination longer than 2 days caused a significant reduction in the viscosity (P<0.05). It was not possible to state any significant differences in viscosity between porridge produced with or without a respite period. However, porridge produced by including a respite period contained a significant higher amount of glucose and maltose, compared with porridge made without this processing step (P<0.05).     

Effect of fermentation on HCl-extractability of minerals from rice-defatted soy flour blend

Buttermilk fermentation at 25, 30 and 35°C for 12, 18 and 24 h brought about a significant increase in non-phytate and HCl-extractable phosphorus with a corresponding decline in phytate phosphorus of a rice-defatted soy flour blend mixed in a 50 : 50 proportion. The HCl-extractabilities of calcium, iron, zinc, copper and manganese from the rice-defatted soy flour blend also improved. Higher HCl-extractability of minerals may be partly ascribed to the decreased content of phytic acid, as a significant negative correlation between the phytic acid and HCl-extractability of dietary essential minerals was obtained.     

Paddy rice stored under hermetic conditions: The effect of relative humidity,temperature and storage time in suppressing Sitophilus zeamais and impact on rice quality

The aim of this study was to analyse the effect of relative humidity in suppressing Sitophilus zeamais, in paddy rice stored under hermetic conditions, during four and seven months, at different average temperatures, as well as the impact on rice quality.Hermetic bags, GrainPro^® SuperGrainbag^® Farm™, were used to store two rice varieties under three different relative humidities: 67%, 75% and 85% RH, and average temperatures of 14 °C, 17 °C and 24 °C, both monitored by Hobo^® Data loggers, with the probe placed inside the bags. CheckpointII Portable O₂ and CO₂ Gas Analyzer was used to assess gas contents on the top and bottom of each bag. At the end of the trials, paddy samples were collected to estimate water activity (a_w). The rheology behaviour of rice pastes prepared with race flour obtained from the different treatments was also evaluated, using a controlled stress rheometer.The results showed that the response of the stored-product insects changes with environmental conditions, O₂ and CO₂ contents. Other parameters were considered; a_w increased with relative humidity and temperature, but decreased with storage time. The relative humidity played an important role, together with the increase of temperature, in suppressing insect populations. A modified atmosphere was naturally produced inside the hermetic bag, under 85% RH, with low O₂ and high CO₂ contents, at different average temperatures, 14 °C and 17 °C. These results demonstrated that S. zeamais can survive, but has no progeny. Under the same conditions, but at the higher average temperature of 24 °C, S. zeamais attained 100% mortality before producing progeny.The increase on respiration rate, registered by CO₂ increase and O₂ decrease, for higher RH values, reduced the viscoelastic functions and changed the starch gelatinization point of Indica and Japonica rice.The results obtained showed that storing paddy hermetically, at low relative humidity, did not change atmospheric content and maintained the viscoelastic functions of the rice pastes.     

The influence of germination conditions on beta-glucan, dietary fibre and phytate during the germination of oats and barley

This study aimed to quantify the changes caused by varying germination conditions on the contents of some bioactive compounds in barley and oats. Samples of the two grains were germinated at temperatures between 10 and 20 °C for a period of 2–6 days, using a two-dimensional central composite design. The germination temperature had only minor effect in comparison with the germination time. Slight changes in the mineral content of the malts were observed, mainly caused by steeping. Phytate has been seen as an anti-nutritional compound, as it complexes minerals and lowers their bioavailability. The phytate content in barley malts was considerably lower than in the native kernels. Variations in the germination conditions did not have a significant effect on phytate content. In oats, degradation of phytate was significantly enhanced by prolonging the germination period. It was possible to retain the amounts of soluble dietary fibre, when short germination periods were applied. However, long germination periods caused an extensive breakdown of soluble dietary fibre, especially beta-glucan. The content of insoluble fibre, however, was increased by applying long germination periods for oat malts.     

Effects of reducing phytate content in sorghum through genetic modification and fermentation on in vitro iron availability in whole grain porridges

Improved iron availability from sorghum porridges will benefit many malnourished communities in rural Africa, where there is a high prevalence of iron deficiency. This research compared the efficacy of reducing sorghum phytate content by genetic modification (GM) and natural lactic acid fermentation on in vitro iron availability in porridges. GM low phytate, non-tannin (38% phytate reduction) and tannin (36% phytate reduction) sorghums and their null controls were processed into thick unfermented and fermented porridges. The inhibitory effect of the tannins seemed to prevent any increase in in vitro iron availability, regardless of the level of phytate reduction. Only the additive effect of GM in combination with fermentation in reducing the phytate content appeared to cause a substantial increase in in vitro iron availability in the GM fermented porridge (30%) made from the non-tannin line, compared to the GM unfermented porridge (8.9%) or the fermented porridge (17.6%) of the control sorghum. This could be of nutritional significance.