Wet-milled Flour Research Articles

Preliminary Study of Hanjeli (Coix lacryma-jobi L) Flour for Food Uses

Job’s tears (Coix lacryma-jobi L) is one of staple crop has a potential in improving food security by substituting rice. It is rich of nutrition and essential chemicals compounds, either as food or herbal. Product yield of job’s tear and quality need to be increased for obtaining flour for various food. This study aimed to investigate the physical and chemical properties of Job’s tear flour was subjected by wet milling and dry milling techniques. The result showed that wet-milled flour had higher value of moisture content compare to the dry-milled flour. Thermal properties of wet- and dry-mill were different each other. Conclusion temperature (Tc) - onset temperature (To) of dry-milled flour was statistically higher than wet-mill flour. The gelatinization enthalpy of wet-milled flour (11.2085 J/g) was higher than dry-milled flour samples (7.8542J/g). Dry milling technique caused more damaged and had more various cracks, fissures and holes on the starch surface than wet.

Effects of Dry-Milling and Wet-Milling on Chemical, Physical and Gelatinization Properties of Rice Flour

Rice flour from nine varieties, subjected to dry- and wet-milling processes, was determined for its physical and chemical properties. The results revealed that milling method had an effect on properties of flour. Wet-milling process resulted in flour with significantly lower protein and ash contents and higher carbohydrate content. Wet-milled flour also tended to have lower lipid content and higher amylose content. In addition, wet-milled rice flour contained granules with smaller average size compared to dry-milled samples. Swelling power at 90°C of wet-milled samples was higher while solubility was significantly lower than those of dry-milled flour. Dry milling process caused the destruction of the crystalline structure and yielded flour with lower crystallinity compared to wet-milling process, which resulted in significantly lower gelatinization enthalpy.

Steeping time and dough fermentation affect the milling behaviour and quality of white kenkey(nsiho), a sour stiff dumpling prepared from dehulled maize grains

White Kenley is a traditional stiff dumpling produced from fermented dehulled maize grains in Ghana. The physico-chemical modifications which occur during combination of various steeping (12, 30 and 48 h) and fermentation (0 h, 12 h and 24 h) times were assessed to study the impact of these unit operations on the quality of white kenkey. Water uptake by soaked grains and the release of metabolites were followed during grains steeping and particle size distribution after milling was determined. Steeping time exceeding 24 h was required to produce a fine wet milled flour while water uptake was completed after 8–10 h. This was parallel to hydrolysis of proteins and/or hemicelluloses which occurred after 16 h. Changes in acidity and glucose content were determined in the grain after steeping and in the dough after fermentation. The texture of the kenkey was determined using a texture analyzer. Increases in acidity were higher during dough fermentation than in steeping. Stickiness of the white kenkey decreased consistently with steeping time. Principal Component Analysis showed that a combination of long steeping and short fermentation times gives white kenkey with low stickiness (and high fineness), low acidic taste and low fermented odour.

건식 및 습식제분 흑미 쌀가루의 물리화학적 특성

The physicochemical properties of black rice flours produced from dry and wet milling were carried out to investigate their applications in food processing industry. The dry milled black rice flours showed lower fat, protein, ash, and anthocyanin contents than those of wet milled black rice flours with no effect due to number of millings. Average particle sizes (379～288 ㎛) of dry milled flours were bigger than those (336～253 ㎛) of wet milled flours. Particles with 60 mesh or more increased with increasing milling times. Wet milled flours had higher damaged starch, water solubility index (WSI), and water absorption index (WAI) compared to dry milled flours. Pasting properties measured by rapid visco analyzer (RVA) resulted in higher pasting temperatures in dry milled flours (62.5～69.4℃) than wet milled flours (46.1～46.4℃). As the number of milling times increased, pasting temperature of wet milled flours were not effected. Dry and wet milling resulted in reduced trough, final viscosity, and consistency with increasing milling times.

Retention of Provitamin A Carotenoids in High β-Carotene Maize (Zea mays) During Traditional African Household Processing

High beta-carotene maize, biofortified with beta-carotene through plant breeding, is being developed as a cost-effective, sustainable agronomic approach to alleviating the problem of vitamin A deficiency in Africa. We used high beta-carotene maize (10.49+/-0.16 microg beta-carotene/g) to prepare traditional maize porridges and compared the carotenoid contents in the following: (1) whole kernels; (2) wet milled flour; (3) wet milled flour, fermented; (4) wet milled flour, cooked; (5) wet milled flour, fermented and cooked. The cumulative losses of beta-carotene in the final, cooked products were 24.5% (95% CI 22.8-26.2%) and 24.8% (95% CI 23.1-26.5%), for the fermented and unfermented porridges, respectively. Thus, fermentation, a traditional technology with documented nutritional and other health benefits, does not adversely affect the retention of beta-carotene in porridges prepared with high beta-carotene maize. The relatively good retention of beta-carotene during traditional maize processing provides additional experimental support for the feasibility of maize biofortification as a means to alleviate vitamin A deficiency.

β‐Carotene retention during African home‐based processing of biofortified maize

More than any other continent, Africa depends on maize as a food source. The HarvestPlus program is developing maize biofortified with beta-carotene as a cost-effective, sustainable agronomic approach to alleviating the problem of vitamin A deficiency in Africa. We used biofortified maize (10.5 ± 0.2 μg β-carotene/g) to prepare traditional maize porridges and compared the carotenoid contents in the following: whole kernels; wet milled flour; wet milled flour – fermented; wet milled flour – cooked; wet milled flour – fermented and cooked. β-Carotene losses were expressed as a percentage of the initial βcarotene content in the raw whole kernels. The cumulative loss of βcarotene in the final fermented, cooked product was 24.5% (95% CI 22.8–26.2%); a 7.3% (95% CI 5.6–9.0%) loss occurred during the preparation of wet milled flour; a 10.2% (95% CI 8.5–11.9%) loss during fermentation, and a 6.9% (95% CI 5.2–8.6%) loss during cooking. When the fermentation step was omitted, the loss during the cooking step increased to 17.5% (95% CI 15.8–19.2%). Thus the β-carotene contents in the final products, fermented and unfermented porridges, were not significantly different. This study provides initial information regarding cooking retention of provitamin A carotenoids as a basis for predicting the bioefficacy of biofortified maize in combating vitamin A deficiency. Supported by USAID/CIAT.

Morphology and physicochemical changes in rice flour during rice paper production

Rice flour samples from four steps of rice paper processing were prepared from rice grain, Chainart 1 variety: wet-milled flour (WMF), 24 hour soak-milled flour (24SF), 48 hour soak-milled (48SF), and dried rice paper (DRP). Decrease in protein, fat and amylose content occurred during prolonged fermentation but increase of ash content due to addition of salt occurred. Because of lactic acid bacteria activity, increases occurred in titratable acidity as lactic acid in soaking water during fermentation. Scanning electron microscopy revealed that starch granule surfaces wilted and showed corrosion channels with longer fermentation. Pasting and thermal properties of the four samples were significantly different; 24SF and 48SF showed lower peak viscosity, breakdown and final viscosity. Increasing fermentation time increased gelatinization temperature, endothermic energy and relative crystallinity. The results suggest that lactic acid and enzyme hydrolysis during fermentation in rice paper processing caused significant decrease in amorphous structure and increase in crystallinity in rice starch.

Effect of Raw Material Preparation on Rice Vermicelli Quality

The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated. The effect of flour particle size on rice vermicelli quality was also determined. The milling method affected chemical compositions and all physicochemical properties of the flour. A higher degree of starch damage occurred in drymilled flour. Rice vermicelli made from dry-milled flour had higher cooking losses and softer texture than that made from wet-milled flour and the commercial reference products. Flour particle size influenced both cooking and textural quality of rice vermicelli but did not influence the water absorption index. Flours with larger particle sizes gave vermicelli with higher cooking loss and less desirable texture than flours with smaller particle sizes. Flour with particle sizes less than 200 mesh produced acceptable vermicelli in terms of cooking and textural quality.

The Effect of Heating at Subgelatinization Temperatures on Enzymatic Digestibility of Corn Starch

The effect of heating at 50 and 55°C on enzymatic digestibility of corn starch was investigated using flours from two corn hybrids (Furio and CMS 8806) prepared by dry- and wet-milling processes. Results obtained show that the enzyme-digestible starch percentage, in all cases, increases with heating time due to changes in the internal structure of the starch granules. The flours from dry milling have an enzyme-digestible starch percentage higher than that observed in wet milled flours with high moisture content.