Compositional and nutritional properties of tef and tef-based food products

In this PhD study, nutritional and health importance of tef, an ancient cereal, was studied. Tef is a cereal originated in Ethiopia where it has been used as a staple cereal. Currently, this cereal is becoming popular in the western countries, however, there is scarcity of information regarding its nutritional and health benefits. This study focused on key nutritional issues in tef flour, injera, porridge and bread: phenolic content and antioxidant capacity, mineral content and bioaccessibility, starch digestibility, protein digestibility and its compliance as a gluten free ingredient. The results showed that tef contains higher Fe, Zn and Ca than other cereals and fairly high amount of digestible proteins. Tef also contains high phenolic content and antioxidant capacity. It is also in compliance with the European Union Food Regulation Directive as a gluten free cereal. Fresh traditional foods such as tef injera-pancake and porridges may cause high post prandial glucose level, while fresh conventional tef bread could only cause a moderate increase in blood glucose level

Effect of sourdough addition and storage time on in vitro starch digestibility and estimated glycemic index of tef bread

The effect of sourdough amount and storage time on starch digestibility and estimated glycemic index (eGI) of tef bread was investigated. The rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) of 0-30% sourdough fresh tef breads ranged from 49 to 58, 16 to 29 and 20 to 26 g/100 g starch, respectively. Storage of tef breads up to 5 days decreased the RDS by more than 2-fold while SDS and RS increased by 2 and 3 fold, respectively. The eGI for fresh and stored breads ranged from 39 to 89. Addition of sourdough increased the eGI of fresh breads while no uniform pattern was seen in the stored breads. As the storage time increased, all the breads showed a decrease in eGI. In vivo study is necessary to further investigate the effect of sourdough on GI of tef bread

Evaluation of the composition and quality of watermelon and mango juices fermented by Levilactobacillus brevis, Lacticaseibacillus casei and Pediococcus pentosaceus and subsequent simulated digestion and storage

This research article was published by John Wiley & Sons, Inc., 2022This study evaluated the composition of watermelon and mango juices fermented by Levilactobacillus (L.) brevis, Lacticaseibacillus (La.) casei and Pediococcus (P.) pentosaceus and subsequently simulated in vitro digestion and storage (4°C for 35 days). After fermentation (24 h), the microorganisms grew (~9 log CFU mL−1) and fermented watermelon (FWJ) and mango juice (FMJ) became more red and yellow, respectively. DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging capacities significantly increased in L. brevis and La. casei FMJ. After in vitro digestion, all the strains except La. casei in FMJ significantly decreased (P < 0.05), and P. pentosaceus survival was 2.4 and 4.5 times higher in FWJ and FMJ, respectively, than as pure culture. After storage, cell counts remained above 7 log CFU mL−1, and no changes in quality attributes, total phenolic content and antioxidant capacity were recorded in P. pentosaceus FMJ. Thus, watermelon and mango are suitable matrices for lactic acid bacteria

Yoghurt and curd cheese addition to wheat bread dough: Impact on in vitro starch digestibility and estimated glycemic index

The effect of yoghurt and curd cheese additions on pasting properties, starch digestibility and estimated glycemic index of wheat bread were studied. Yoghurt and curd cheese incorporations (6% up to 25% w/w) promoted considerable changes on starch performance based on gelatinization and final dough consistency properties. These changes led to a significant impact on starch digestibility, reducing significantly the rapidly digestible starch while increasing the resistant starch. The estimated glycemic index reflected the changes promoted on starch performance from both dairy products addition, at higher level tested (25%): a significant reduction of around 30% for yoghurt bread and 38% for curd cheese bread, was obtained, resulting in medium to low (55–69) glycemic index breads. Correlations were found between pasting properties, starch digestibility and glycemic index, revealing that the effects observed are proportional to the levels of dairy products added. Microstructure images of the starch granules supported these findingsinfo:eu-repo/semantics/publishedVersio

Effect of Lactic Acid Fermentation on Volatile Compounds and Sensory Characteristics of Mango (Mangifera indica) Juices

This research article published by MDPI, 2022Fermentation is a sustainable bio-preservation technique that can improve the organoleptic quality of fruit juices. Mango juices were fermented by monoculture strains of Lactiplantibacillus plantarum subsp. plantarum (MLP), Lacticaseibacillus rhamnosus (MLR), Lacticaseibacillus casei (MLC), Levilactobacillus brevis (MLB), and Pediococcus pentosaceus (MPP). Volatile compounds were sorbed using headspace solid phase microextraction, separated, and identified with gas chromatography mass spectrometry. Forty-four (44) volatile compounds were identified. The control, MPP, and MLB had higher amounts of ethyl acetate, ethyl butyrate, 2-hexenal, 2,6-nonadienal, 2,2-dimethylpropanal, β-selinene, γ-gurjunene, α-copaene, and δ-cadinene, while MLC, MLP, and MLR had higher amounts of 2,3-butanedione and a cyclic hydrocarbon derivate. Consumers (n = 80) assessed their overall liking and characterized sensory attributes (appearance, color, aroma, flavor, consistency, acidity, and sweetness) using check-all-that-apply, and penalty analysis (just-about-right). Overall liking was associated with ‘mango color’, ‘pulp’, ‘mango aroma’, ‘sweet’, ‘natural taste’, and ‘mango flavor’ that described the control, MLB, MLC and MPP. Juices MLR and MLP were described as ‘bitter’, ‘sour’, ‘aftertaste’, and ‘off-flavor’. Multivariate analysis revealed relationships between the volatile com pounds, mango juices fermented by different lactic acid bacteria, and sensory characteristics. Thus, the type of lactic acid bacteria strains determined the volatile and sensory profile of mango juices

Effect of lactic acid fermentation of watermelon juice on its sensory acceptability and volatile compounds

This research article published by Elsevier Ltd., 2021Fermentation increases food shelf-life but is characterized by changes that affect product's perception. Watermelon juice was fermented with Lactobacillus plantarum (WJ-LP), L. rhamnosus (WJ-LR), L. casei (WJ-LC), L. brevis (WJ-LB) and Pediococcus pentosaceus (WJ-PP). Their sensory characteristics and volatile compounds were investigated by consumers and Headspace Solid Phase Microextraction integrated with Gas Chromatography-Mass Spectrometry, respectively. WJ-PP and WJ-LB were most liked and perceived with ‘watermelon-flavor’, ‘natural taste’, ‘sweet’ and ‘watermelon-color’ while WJ-LC, WJ-LP and WJ-LR were least liked and perceived as ‘sour’, ‘bitter’, ’off-flavor’, ‘aftertaste’ and ‘intense-flavor’. Fifty-four volatiles were identified. After fermentation, alcohols, ketones, monoterpenes, acids, and furans increased while aldehydes and alkanes decreased. Lactic acid fermentation introduced 4-decanone and 2,3-butanedione in WJ-LB, WJ-LC, WJ-LP and WJ-LR, however, heptanal, 2-heptenal, 2,6-nonadienal, 2-decenal, and 2,4-decadienal in WJ-LC, heptanal, 2-hexenal, 2-heptenal, 2,6-nonadienal, 2-decenal and octanal in WJ-LR and 2,6-dimethyl-2,6-octadiene in WJ-LP disappeared. Juice sensory profiles were associated with their volatile compounds

Dissecting the facts about the impact of contaminant iron in human nutrition : a review

Background: Iron, the building block of hemoglobin, plays a crucial role in facilitating tissue oxygen delivery. Iron deficiency anemia, a morbid health condition, is among the leading global health problems. In an attempt to control this, iron fortification, supplementation and dietary diversification strategies have been used. Researches show that plant-based food products, particularly in developing countries, contain an abundant amount of contaminant iron, i.e. non-endogenous plant iron. However, the nutritional significance or bioaccessibility of contaminant iron is not well characterized. Scope and approach: In this review, the importance of contaminant iron in human nutrition is investigated with a special focus on contaminant iron sources, bioaccessibility, existing analytical techniques, and iron fortification's impact on gut microflora. Key findings and conclusions: Plant-based Food products, particularly in developing countries, contain a great deal of contaminant iron originating from soil and processing equipment. Based on the existing literature, no concrete conclusion could be drawn regarding the bioaccessibility and/or nutritional benefits of contaminant iron highlighting the need for further studies. Whether the external labeling of stable iron isotopes method reliably differentiates and quantifies bioaccessible contaminant iron needs verification

Tef : the rising ancient cereal : what do we know about its nutritional and health benefits?

This review covers the nutritional significance of tef cereal as compared to other common cereals with emphasis on carbohydrate content and starch digestibility, protein content, iron and zinc bioavailability and antioxidant potentials. Tef is a gluten free cereal and contains the highest iron and calcium among other cereals. It has high micro- and macro- nutritional profile and is becoming globally popular in the healthy grain food chain. Tef starch has a high gelatinization temperature, an essential precondition in the preparation of low glycemic index foods. There are significantly conflicting reports of iron content of tef ranging from 5 to 150 mg/100 g dm. The traditional fermentation of injera reduced majority of the phytic acid but no significant change to mineral bioavailability was observed. This review indicated that studies on starch digestibility, protein characterization, amylase and protease inhibitors, mineral bioavailability and antioxidant potentials are needed to further explore the nutritional and health benefits of tef

Antioxidant potentials and phenolic composition of tef varieties : an indigenous Ethiopian cereal

Tef, Eragrostis tef (Zucc.) Trotter, is a cereal crop originated and diversified in Ethiopia, where it is used to produce a range of food products. This study aimed to profile and quantify the phenolic composition and antioxidant potential of seven tef grain varieties. Soluble and bound phenolics ranged from 37 to 71 and from 226 to 376 mg of gallic acid equivalent/100 g dry basis (db), and soluble and bound flavonoid contents varied between 36 and 64 and between 113 and 258 mg of catechin equivalent/100 g db, respectively. Protocatechuic, vanillic, syringic, p-coumaric, sinapic, ferulic, and rosmarinic acids, catechin, and naringenin were detected at least in three of the varieties studied. The dominant phenolic compounds were catechin, rosmarinic acid, and ferulic acid in the soluble extracts, whereas ferulic, rosmarinic, and p-coumaric acids were the dominant ones in the bound extract. Gallic, caffeic, and salicylic acids were not detected in any of the varieties studied. The majority (>84%) of tef grain phenolics were found in bound form, contributing >84% of total 2,2-diphenyl-1-picrylhydrazyl antioxidative capacity and >80% of total ferric reducing antioxidant power. These results clearly demonstrated the differences in phenolic profile among tef grain varieties. These results are relevant for developing healthy and nutritious tef-based food products