Effects of Processing on Phytonutrient and Nutritional Composition of Finger Millet (Eleusine coracana): The Neglected Crop of Africa

Millets are termed as nutricereals since they are nutritionally superior to major cereals with respect to protein, energy, vitamins and minerals. The aim of  this research was to investigate the effects of processing techniques on the proximate composition and reduction of phytonutrients in finger millet  grains. Germination (72hrs) and natural fermentation (24hrs) process of finger millet seeds improved crude protein. A significant (p<0.05) variation was  noticed within 72hrs of germination in the total amount of calcium, iron and phosphorous due to the transfer of nutrients from the seed material to the  growing embryo. The flour was extruded at a temperature of 110 ºC and 130ºC, a screw speed of 200 and 250 rpm, and 17 and 21 feed moisture content.  The highest expansion ratio and lowest bulk density was obtained at temperature of 130 ºC, screw speed of 250 rpm and 17% moisture content. A  significance difference was observed during extrusion processing on elimination of phytate as compared to germination and fermentation. Fermentation  (48 hrs) and extrusion (130 ºC) were found to be the best process methods for the reduction of the phytate and tannins, respectively. The  improved physical properties of extrudates and level of reduction of phytonutreints indicate the possibility of diversifying utilization of finger millet in the  form different indigenous community based added value products and novel commercial value added products at manufacturing industry level.&nbsp

Chemical Composition of local and Improved finger Millet [Eleusine Corocana (L.) Gaetrtin] varieties grown in Ethiopia

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Microwave Processing of Food and Biological Materials: Principles and Various Processing Applications

Microwave processing is one of the novel food processing technologies that use electromagnetic radiation in the wavelength and frequency between 1 mm to 1 m and 300 MHz to 300 GHz, respectively. In this review, principles and various applications of microwave technology for food processing are addressed. A systematic literature search was conducted by using, Google Scholar and, Web of Science, Open access theses and dissertations on the principles and application of microwave processing of food were summarized. Additionally, references of each selected publication were examined to get more relevant articles. In microwave processing, the food material absorbs microwave energy directly, and internally, and converts it to heat. The technology is applicable for different unit operations in food industries such as cooking, heating, drying, pasteurization, sterilization, thawing, tempering, baking, blanching, and the extraction of important food biomaterials. Microwave processing is highly advantageous over conventional food processing techniques, in terms of retaining the nutritional content of the food and reducing processing time. Consequently, the breakthrough of the technology in food processing industry has been predicted before. However, the potential of microwave technology is not widely exhausted in Africa. It is associated with a lack of awareness, a priority setting on the application of emerging technologies for safe and high quality value added products; moreover, its high initial investment and operational power cost may become a bottleneck for food processing companies in Africa. Therefore, food innovation centres in Africa should drive high performance standards from technology adoption to improve the application of microwave technology in food industries

Effects of Pre-treatments and Drying Methods on Chemical Composition, Microbial and Sensory Quality of Orange-Fleshed Sweet Potato Flour and Porridge

Abstract This study was aimed to evaluate the effect of pre-treatments and drying methods on the chemical composition (proximate composition, β-carotene content and phytochemicals), functional properties, microbial and sensory of orange-fleshed sweet potato flour and porridge. Physical (blanching) and chemical (1% salt, 0.5% citric acid solution soaked for 20 min) of the sliced OFSP followed by drying (sun, solar and fluidized bed dried) with complete randomized design for chemical composition, functional properties, and microbial load analysis and randomized complete block design was used for sensory analysis. The moisture (4 -8%), protein (4 -8%), fat (0.9 -2.5), ash (4 -8%), fiber (3.5 -7%), total carbohydrates (80 -84%) measured as a function of treatment and drying. The energy contribution of OFSP was determined by difference of the proximate excluding the fiber (352.9-365.6kcal/100g). The salt treated and FB dried had significantly lowest moisture content and highest ash content, citric acid treated and FB dried had significantly highest protein content and gross energy, control and FB dried had significantly highest fiber content, control and sun dried had significantly highest fat content and blanched and FB dried had significantly highest total carbohydrates. The β-carotene (82 -127μg/g), tannin (74 -108mg/100g) and phytate content (51 -98mg/100g) was measured. Blanched and FB dried was observed better in retention of β-carotene and reduction of phytochemicals (tannin and phytate). The salt treated and FB dried was measured increment with WAC, viscosity and lowest LGC, blanched and FB had highest OAC and high bulk density in the control. The microbial analysis showed OFSP porridge within microbiological acceptable limit. The sensory acceptability showed OFSP was accepted in all sensory attributes. In conclusion, the blanching and FB drying techniques were the best approach in retaining the nutrients

Effect of mill type and mechanical kneading conditions on fermentation kinetics of tef dough during injera making and phytate to mineral molar ratio of injera

Producción CientíficaInjera is Ethiopian traditional fermented flatbread which is made mostly from tef flour. Tef grain is milled and the flour kneaded to have batter-like dough which will ferment before injera baking. The influence of mill type: hammer mill (HM), disc mill (DM) and blade mill (BM) and mechanical kneading speed-time combinations (K1, K5, and K9) on fermentation kinetics was investigated. Phytate to mineral molar ratio (Fe, Zn and Ca) of tef injera was also investigated as affected by mill type and different kneading conditions. In both milling and kneading levels, maltose was the highest sugar concentration initially, followed by glucose and fructose. As fermentation continued, a similar trend in maltose breakdown was seen among HM, DM, and BM. However, different patterns of glucose and fructose breakdown were seen on HM than DM and BM. Similarly, HM had a different pattern in increment of lactic acid concentration than DM and BM. Similar trend in maltose concentration was seen between K1, K5, and K9. Again glucose breakdown and the increment of lactic acid in K9 were different than that of K1 and K5. Phytate/mineral molar ratio of BM was significantly different (p<0.05) from HM and DM. There was also a significant difference (p<0.05) in phytate/mineral molar ratio between K1, K5, and K9. Decreased phytate/mineral molar ratio was seen with increasing of kneading speed (rpm) for a longer period of time. The effect of mill type and kneading speed and time combinations on fermentation kinetics and phytate/mineral molar ratio were significant.Ministerio de Economía y Competitividad - FEDER (AGL2015-63849-C2-2-R)Junta de Castilla y León - FEDER (Project VA072P17

Effects of phytase-supplemented fermentation and household processing on the nutritional quality of Lathyrus sativus L. seeds

Grass pea (Lathyrus sativus L.) is commonly consumed in cooked, fermented, and roasted forms in Ethiopia. However, the impacts of household processing practices on its nutrients, antinutrients, and toxic compounds have not been adequately studied. Therefore, the effects of household processing and fermentation in the presence and absence of a phytase on the contents of β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), myo-inositol phosphates, crude protein, minerals and the in vitro bioaccessibility were investigated. Fermentation exhibited a significant decline in β-ODAP (13.0–62.0%) and phytate (7.3–90.5%) irrespective of the presence of phytase. Pressure and pan cooking after discarding the soaking water resulted in a 27.0 and 16.2% reduction in β-ODAP. A 30% reduction in phytate was observed during germination followed by roasting. In addition, germination resulted in a significant (p < 0.05) increase in crude protein. Germination and germination followed by roasting resulted in the highest Fe bioaccessibilities (more than 25 fold higher compared to untreated samples) followed by pressure cooking and soaking. Processing also improved Zn bioaccessibilities by 50.0% (soaked seed without soaking water), 22.5% (soaked seed with soaking water), and 4.3% (germination). Thus, the processing technologies applied were capable of reducing the content of phytate (InsP6) and β-ODAP with a concomitant increase in mineral bioaccessibilities. Processing of grass peas could therefore contribute to their more widespread utilization

The effect of mechanical kneading and absit preparation difference on tef injera quality

Producción CientíficaThe aim of this study was to investigate the effect of mechanical kneading and ‘absit’ preparation difference on the quality of tef injera, the staple food of Ethiopians. Standard methods were adopted to determine the starch fraction, total phenol, flavonoid, phytate and tannins of injera. Sensory injera quality was assessed using 9-point-hedonic scale. Change in kneading conditions (time/speed) did not significantly affect the free sugar (FSG), slowly digestible starch (SDS), resistant starch (RS), total starch(TS) and starch digestion rate index (SDRI). On the other hand, significant variation was observed in rapidly available glucose and rapidly digestible starch (RAG and RDS). Flavonoids, total phenolics and phytate contents varied significantly at different kneading time- speed combinations. Injera sensory quality was also significantly affected due to change in kneading conditions. Kneading condition 5 (3 min at speed 6) has the highest injera overall acceptability while kneading condition 9 (7 min at speed 12) had the lowest. In addition to kneading conditions, absit preparation (water to fermented dough ratio) was also found to affect the quality of tef injera. Absit # 3 made from 100 ml of fermented dough and 900 ml of water had the highest injera overall acceptability while, the lowest was observed on Absit # 4 made from 300 ml of fermented dough and 100 ml of water. In conclusion, both kneading and absit preparation significantly influenced starch hydrolysis, flavonoids, total phenolics and phytate contents as well as sensory quality of injera.Ministerio de Economía y Competitividad - FEDER (AGL2015- 63849-C2-2-R)Junta de Castilla y León) - FEDER (Project VA072P17

Influence of milling type on tef injera quality

Producción CientíficaInjera is an Ethiopian flat bread that is mostly made from tef flour. Injera making on an industrial scale holds a significant economic and social interest but requires a thorough study of how the process variables affect the product quality. The aim of this work was to investigate the effects of mill type (hammer, disc, and blade) on injera sensory quality and starch digestibility. The application of software for the determination of injera quality descriptors and its comparison with visual human eye evaluation was also established. Injera made with disc mill flour had higher overall acceptability (6.6) than that obtained from hammer mill (4.2) and blade mill (4.1) flours. The injera made with blade mill flour obtained the lowest rapidly available glucose and rapidly digestible starch. The outcome of introducing software for the determinations of injera number of eyes was found effective; its difference with human eye determination was insignificant.Ministerio de Economía y Competitividad - FEDER (AGL2015-63849-C2-2-R)Junta de Castilla y León - FEDER (Project VA072P17

Effect of Ultrasound-Assisted Extraction of Moringa stenopetala Leaves on Bioactive Compounds and Their Antioxidant Activity

Moringa stenopetala je višenamjenska biljka s izraženim nutritivnim i terapeutskim svojstvima. Svrha je ovoga rada bila ispitati utjecaj vremena i temperature ekstrakcije potpomognute ultrazvukom na izdvajanje bioaktivnih spojeve i antioksidacijsku aktivnost ekstrakta lista biljke M. stenopetala. Ekstrakcija je provedena pri temperaturama od 30, 40 i 50 °C tijekom 10, 20 i 30 minuta. Ispitan je i međusobni utjecaj vremena i temperature ekstrakcije na ukupne udjele fenola i flavonoida, antioksidacijsku aktivnost (mjerenu pomoću ABTS, DPPH i FRAP metoda) i sposobnost keliranja Fe2+ iona. Nakon 20 min ekstrakcije pri 40 °C dobiven je najveći udjel ukupnih fenola u suhoj tvari, izražen kao ekvivalent galne kiseline, i to 46,6 mg/g, te najveći udjel ukupnih flavonoida u suhoj tvari, izražen kao ekvivalent katehina, i to 20,4 mg/g. Pri istim je uvjetima izmjerena najveća antioksidacijska aktivnost ekstrakata, izražena kao ekvivalent Troloxa u suhoj tvari, i to 336,5 mg/g prema DPPH metodi, 581 ,8 mg/g prema ABTS metodi i 1 33,3 mg/g prema FRAP metodi. Sposobnost keliranja, izražena u ekvivalentima EDTA u suhoj tvari, bila je 28,4 mg/g. Najmanje bioaktivnih spojeva i najmanja antioksidacijska aktivnost opaženi su u ekstraktima dobivenim nakon 30 min pri 50 °C, te nakon toga u ekstraktima dobivenim pri nižoj temperaturi (30 °C) i kraćem vremenu trajanja (10 min). Morfološka je analiza ostataka dobivenih nakon ekstrakcije pomoću pretražnog elektronskog mikroskopa pokazala veća oštećenja strukture uzorka pri duljem vremenu ekstrakcije. Stoga je zaključeno da su temperatura od 40 °C i vrijeme ekstrakcije od 20 min optimalni za izdvajanje bioaktivnih spojeva iz lišća biljke M. stenopetala.Moringa stenopetala is a multipurpose plant having high nutritional and medicinal values. The aim of this study is to evaluate the effect of time and temperature of ultrasound-assisted extraction on bioactive compounds and antioxidant activities of M. stenopetala leaf extract. The ultrasound-assisted extraction took place at each of 30, 40 and 50 °C for 10, 20 and 30 min. The study also included the analysis of the interaction effects of time and temperature on the total phenolic content, total flavonoid content, antioxidant activity (ABTS and DPPH assay), FRAP and chelating activity. The highest total phenolic content, expressed in mg gallic acid equivalents per g dry mass, was 46.6 and total flavonoid content, expressed in mg catechin equivalents per g dry mass, was 20.4 at 40 °C for 20 min. Under the same conditions, the highest antioxidant activities evaluated by DPPH, ABTS and FRAP, expressed in mg Trolox equivalents per g dry mass, were 336.5, 581.8 and 133.3 respectively, and chelating activity, expressed in mg EDTA equivalents per g dry mass, was 28.4. The lowest amounts of bioactive compounds and antioxidant activities were observable when the extraction occurred at 50 °C for 30 min, followed by the extraction at lower temperature (30 °C) for shorter time (10 min). The morphological analysis of the residues obtained after extraction using scanning electron microscope indicated that there was a higher ultrasonic destruction of the structural components of the sample at longer extraction time. Therefore, ultrasound-assisted extraction at a temperature of 40 °C for 20 min is the best time-temperature combination to extract bioactive compounds from M. stenopetala leaves