Effect of preprocessing techniques on pearl millet flour and changes in technological properties

Maximizing the Nutritional Benefits and Prolonging the Shelf Life of Millets through Effective Processing Techniques: A Review

Maximizing the nutritional benefits and extending the shelf life of millets is essential due to their ancient significance, rich nutrient content, and potential health benefits, but challenges such as rapid rancidity in millet-based products underscore the need for effective processing techniques to enhance their preservation and global accessibility. In this comprehensive review, the impact of diverse processes and treatments such as mechanical processing, fermentation, germination, soaking, thermal treatments like microwave processing, infrared heating, radio frequency, nonthermal treatments like ultrasound processing, cold plasma, gamma irradiation, pulsed light processing, and high-pressure processing, on the nutritional value and the stability during storage of various millets has been examined. The review encompasses an exploration of their underlying principles, advantages, and disadvantages. The technologies highlighted in this review have demonstrated their effectiveness in maximizing and extending the shelf life of millet-based products. While traditional processes bring about alterations in nutritional and functional properties, prompting the search for alternatives, novel thermal and nonthermal techniques were identified for microbial decontamination and enzyme inactivation. Advancements in millet processing face challenges including nutrient loss, quality changes, resource intensiveness, consumer perception, environmental impact, standardization issues, regulatory compliance, and limited research on combined methods.

Effects of Lactic Acid Bacteria on Reducing the Formation of Biogenic Amines and Improving the Formation of Antioxidant Compounds in Traditional African Sourdough Flatbread Fermentation

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Levilactobacillus brevis, and Weissella cibaria, significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

Investigating the role of Lactiplantibacillus plantarum vs. spontaneous fermentation in improving nutritional and consumer safety of the fermented white cabbage sprouts

Brassicaceae sprouts are promising candidates for functional food because of their unique phytochemistry and high nutrient density compared to their seeds and matured vegetables. Despite being admired for their health-promoting properties, white cabbage sprouts have been least explored for their nutritional significance and behavior to lactic acid fermentation. This study aimed to investigate the role of lactic acid fermentation, i.e., inoculum vs. spontaneous, in reducing intrinsic toxicants load and improving nutrients delivering potential of the white cabbage sprouts. White cabbage sprouts with a 5-7 cm average size were processed as raw, blanched, Lactiplantibacillus plantarum-inoculated fermentation, and spontaneous fermentation. Plant material was dehydrated at 40 °C and evaluated for microbiological quality, macronutrients, minerals, and anti-nutrient contents. The results indicate L. plantarum inoculum fermentation of blanched cabbage sprouts (IF-BCS) to increase lactic acid bacteria count of the sprouts from 0.97 to 8.47 log CFU/g. Compared with the raw cabbage sprouts (RCS), inoculum fermented-raw cabbage sprouts (IF-RCS), and spontaneous fermented-raw cabbage sprouts (SF-RCS), the highest content of Ca (447 mg/100 g d.w.), Mg (204 mg/100 g d.w.), Fe (9.3 mg/100 g d.w.), Zn (5 mg/100 g d.w.), and Cu (0.5 mg/100 g d.w.) were recorded in IF-BCS. L. plantarum-led fermentation of BCS demonstrated a reduction in phytates, tannins, and oxalates contents at a rate of 42%, 66%, and 53%, respectively, while standalone lactic acid fermentation of the raw sprouts reduced the burden of anti-nutrients in a range between 32 and 56%. The results suggest L. plantarum-led lactic acid fermentation coupled with sprout blanching is the most promising way to improve the nutritional quality and safety of the white cabbage sprouts.

Nutritional, Biochemical, and Functional Properties of Pearl Millet and Moringa oleifera Leaf Powder Composite Meal Powders

This study sought to improve pearl millet's nutritional, functional, and biochemical properties through malting and fermentation. Moringa oleifera leaf powder (MLP) was used as a fortificant. Mixture design was used to find optimal proportions for each component that yielded a high protein and or low saturated fat content. Twelve mixtures with varying ratios of fermented and malted pearl millet flour ranging between 30-65% and MLP between 5-15% were generated through I-Optimal mixture design. The mixtures were wet-cooked, freeze-dried, and analysed for protein and fat content. The data obtained were fitted to a linear mixture model, and the search for the optimum was conducted using Numerical Optimisation for maximising protein and minimising saturated fat. The linear model was suitable for explaining total protein and saturated fat variation with r2 of 0.50 and 0.51, respectively. Increasing MLP increased protein content. Two final formulations, Optimisation Solution 1 (OS1) and Optimisation Solution 2 (OS2), were generated through the optimisation process. Pearl millet's protein content increased by up to 22%, while saturated fat decreased by up to 13%; ash content increased by 75%. Polyphenol content and oxygen radical absorbance capacity increased by 80% and 25%, respectively. Final and peak viscosity were reduced by 90% and 95%, respectively.

Exploring Scientific Validation of Millets in Contemporary Healthcare: A Traditional Food Supplement

Millets, small-seeded grasses, are gaining interest for their nutrition and health benefits. This abstract provides a comprehensive overview of millets' pharmacological activities, highlighting their rich bioactive compounds. These compounds, including phenolic compounds, flavonoids, and dietary fibers, contribute to antioxidant effects, safeguarding against chronic diseases. Millets also possess anti-inflammatory properties, potentially alleviating conditions, like arthritis and asthma. They show anti-carcinogenic potential, possibly preventing various cancers' development through mechanisms, like apoptosis induction and inhibiting tumor growth. Moreover, millets offer hypolipidemic and hypoglycemic effects, beneficial for managing conditions, such as dyslipidemia and diabetes. Their high dietary fiber and resistant starch content regulate blood lipids and glucose, reducing the cardiovascular risk. Additionally, millets act as antimicrobials, inhibiting pathogens and serving as natural alternatives to synthetic antimicrobials. They exhibit immunomodulatory effects, enhancing immune function and response. Overall, millets' pharmacological properties, including antioxidant, antiinflammatory, anti-carcinogenic, hypolipidemic, hypoglycemic, antimicrobial, and immunomodulatory traits, position them as functional foods with varied health benefits. Further research can integrate millets into preventive and therapeutic approaches for diverse diseases.

Health-Promoting Potential of Millet: A Review

Being a key source of animal food, millet production has been sharply increasing over the last few years in order to cope with the dietary requirements of the ever-increasing world population. It is a splendid source of essential nutrients such as protein, carbohydrates, fat, minerals, vitamins, and also some other bioactive compounds that eventually help through multiple biological activities, including antioxidant, anti-hyperglycemic, anti-cholesterol, anti-hypertensive, anthropometric effects and regulation of gut microbiota composition. These bioactive compounds, nutrients, and functions of cereal grains can be affected by processing techniques such as decortication, soaking, malting, milling, fermentation, etc. This study discusses the nutritional and functional properties of millet-incorporated foods and their impact on health, based on around 150 articles between 2015 and 2022 from the Web of Science, Google Scholar, Food and Agriculture Organization of the United Nations (FAO), Breeding Bid Survey (BBS), and FoodData Central (USDA) databases. Analyzing literature reviews, it is evident that the incorporation of millet and its constituents into foodstuffs could be useful against undernourishment and several other health diseases. Additionally, this review provides crucial information about the beneficial features of millet, which can serve as a benchmark of guidelines for industry, consumers, researchers, and nutritionists.

Plantain-based diet decreases oxidative stress and inflammatory markers in the testes of rats exposed to atrazine

Exposure to the herbicide atrazine (ATZ) has deleterious effects on male fertility. This fact underscores the need for measures to protect against the detrimental impact of atrazine exposure on male fertility. The study assessed the protective effects of plantain-based diet (PBD) on rat testes exposed to ATZ by exploring oxid-inflammatory homeostasis. The study evaluated the preventive and therapeutic effects of PBD in a two-phased experiment. Male rats were randomized into seven groups for therapeutic model (Control, ATZ only, ATZ recovery, ATZ + 50% PBD, ATZ + 25% PBD, ATZ + 12.5% PBD and ATZ + quercetin-QUE) while the preventive model had ten groups (Control, ATZ, 50% PBD + ATZ, 25% PBD + ATZ, 12.5% PBD + ATZ and QUE + ATZ). The oxidative stress parameters (DNA fragmentation and MDA level), purinergic activity (ATPase), acetylcholine esterase, and inflammatory markers (NO level, MPO activity, and TNF-α) were increased while the Nrf2 levels were decreased by the ATZ treatment. However, the PBD was able to restore the oxido-inflammatory parameters in the rat testes. The chemical fingerprint of the diet revealed that the diets contained 16 bioactive compounds with quercetin being the most prominent compound. Overall, treatment with PBD was able to protect and prevent the toxicity caused by ATZ by modulating the redox and inflammatory status as well as purinergic activity in the rat testes.

Effects of Wet Processing on Physicochemical and Functional Characteristics of Millet Flour

In recent times, millet emerged as a gluten-free alternative cereal with a rich nutritional profile. However, the nutritional value is hindered by antinutritional factors, like tannin and phytic acid, present in the grain. In the current work, wet pre-processing methods, namely steeping, fermentation, germination, and a combination of germination-fermentation were studied for their effect on these antinutritional factors along with other functional and chemical properties of millet flour. Starch hydrolysation due to these wet pre-treatments was found to improve various aspects of the functional properties of millet flour. Steeping and fermentation resulted in increased protein and fat fraction in the treated flour with better water absorption capacity and hygroscopicity. At the same time, germination improved the protein and fibre content with better water solubility and oil absorption capacity. The aqueous environment during these pre-treatments was also found to reduce gelatinisation temperature and content of antinutritional factors in the treated flour samples. The present study indicated that wet pre-processing could be a good value addition to millet flour preparation with better functional and nutritional properties.

Effect of physicochemical properties on popping characteristics of selected pearl millet varieties

BACKGROUND

Pearl millet, commonly known as 'Bajra', is a nutrigrain, mostly used in pulverized form to make unleavened pancakes, dumplings, porridge, etc., in India. Popping, a traditional method of millet processing, is used in making ready-to-eat snacks. Pearl millet is underutilized in India. The present work aims to study the effect of the parameters of pearl millet such as variety, chemical composition, pericarp thickness, amylose content, and processing temperature on the volume expansion ratio and sensory properties of popped pearl millet.

METHODOLOGY

A conventional salt-popping technique was used at three different temperatures (220 °C, 240 °C, and 260 °C) for five pearl millet varieties (ABPC 4-3, AHB 1269, AHB 1666, AIMP 92901, and PPC-6). Parameters such as color, diameter, density, amylose content, pericarp thickness, and proximate composition were analyzed. Popping characteristics such as volume expansion ratio, popping yield, and sensory properties of popped grains were studied.

RESULTS

It was observed that pericarp thickness and amylose content were positively correlated with the popping qualities of grains. AIMP 92901 offered more desirable properties such as suitable moisture content (87.5 g kg^-1 ), lowest equivalent diameter (2.07 mm), highest bulk density (0.84 g cm^-3 ), true density (1.41 g cm^-3 ), pericarp thickness (30.82 μm), and amylose content (19.75 g kg^-1 ) than the other varieties that were studied. Hence, the highest popping yield (72.83%) and expansion ratio (6.15) was observed in the AIMP 92901 pearl millet variety at 260 °C.

CONCLUSION

Conventional salt popping at 260 °C yielded the best popping characteristics. Pearl millet variety AIMP-92 901 developed by VNMKV (Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani), Parbhani was found to have more desirable popping characteristics (in terms of all the parameters explained in results). © 2022 Society of Chemical Industry.

Mineral Content, Functional, Thermo-Pasting, and Microstructural Properties of Spontaneously Fermented Finger Millet Flours

Finger millet is a cereal grain which is superior to wheat and rice in terms of dietary fibre, minerals, and micronutrients. Fermentation is one of the oldest methods of food processing, and it has been used to ferment cereal grains such as finger millet (FM) for centuries. The aim of this study was to investigate the impact of spontaneous fermentation (SF) on mineral content, functional, thermo-pasting, and microstructural properties of light- and dark-brown FM flours. Spontaneous fermentation exhibited a significant increase in the macro-minerals and micro-minerals of FM flours. In terms of functional properties, SF decreased the packed bulk density and swelling capacity, and it increased the water/oil absorption capacity of both FM flours. Spontaneous fermentation had no effect on the cold paste viscosity of FM flours. However, significant decreases from 421.61 to 265.33 cP and 320.67 to 253.67 cP were observed in the cooked paste viscosity of light- and dark-brown FM flours, respectively. Moreover, SF induced alterations in the thermal properties of FM flours as increments in gelatinisation temperatures and gelatinisation enthalpy were observed. The results of pasting properties exhibited the low peak viscosities (1709.67 and 2695.67 cP), through viscosities (1349.67 and 2480.33 cP), and final viscosities (1616.33 and 2754.67 cP), along with high breakdown viscosities (360.00 and 215.33 cP) and setback viscosity (349.33 and 274.33 cP), of spontaneously fermented FM flours. Scanning electron microscopy showed that SF influenced changes in the microstructural properties of FM flours. The changes induced by SF in FM flours suggest that flours can be used in the food industry to produce weaning foods, jelly foods, and gluten-free products that are rich in minerals.

Understanding the Antinutritional Factors and Bioactive Compounds of Kodo Millet (Paspalum scrobiculatum) and Little Millet (Panicum sumatrense)

Kodo and little millet (Kutki) have a variety of phytochemical constituents including derivatives of hydroxybenzoic acid and hydroxycinnamic acids, myricetin, catechin, luteolin, apigenin, daidzein, naringenin, kaempferol, and quercetin with vast health benefits and thus can be utilized as functional food ingredients. Millet-based foods and their food products have physiological and health-promoting impacts, notably antidiabetic, anti-obesity, and cardiovascular disease, and based on the actions of phytochemicals, it plays a major role in the body’s immune system. However, antinutrients (tannins, oxalate, trypsin inhibitor, and phytates) present in these millets restrict their utilization since these factors bind the essential nutrients and make them unavailable. Therefore, this review suggested overcoming the effects of antinutrients in these millets, thereby opening up important applications in food industries that may promote the development of novel functional foods. Various methods were discussed to eliminate the antinutrient factors in these millets, and hence, the review holds immense significance to the food industry for effectively utilizing these millets to develop value-added RTE/RTC products/functional food/beverages.

Fermentation of Cereals and Legumes: Impact on Nutritional Constituents and Nutrient Bioavailability

Fermented food products, especially those derived from cereals and legumes are important contributors to diet diversity globally. These food items are vital to food security and significantly contribute to nutrition. Fermentation is a process that desirably modifies food constituents by increasing the palatability, organoleptic properties, bioavailability and alters nutritional constituents. This review focuses on deciphering possible mechanisms involved in the modification of nutritional constituents as well as nutrient bioavailability during the fermentation of cereals and legumes, especially those commonly consumed in developing countries. Although modifications in these constituents are dependent on inherent and available nutrients in the starting raw material, it was generally observed that fermentation increased these nutritive qualities (protein, amino acids, vitamins, fats, fatty acids, etc.) in cereals and legumes, while in a few instances, a reduction in these constituents was noted. A general reduction trend in antinutritional factors was also observed with a corresponding increase in the nutrient bioavailability and bioaccessibility. Notable mechanisms of modification include transamination or the synthesis of new compounds during the fermentation process, use of nutrients as energy sources, as well as the metabolic activity of microorganisms leading to a degradation or increase in the level of some constituents. A number of fermented products are yet to be studied and fully understood. Further research into these food products using both conventional and modern techniques are still required to provide insights into these important food groups, as well as for an overall improved food quality, enhanced nutrition and health, as well as other associated socioeconomic benefits.

Descriptive sensory analysis of instant porridge from stored wholegrain and decorticated pearl millet flour cooked, stabilized and improved by using a low-cost extruder

Pearl millet flour, particularly wholegrain flour, is highly susceptible to development of rancid aromas and flavors during storage. Grain decortication and extrusion cooking using a friction-heated single-screw extruder were investigated as potential flour stabilization processes. Raw and extruded wholegrain and decorticated grain pearl millet flours were stored at ambient (25°C) and elevated (40°C) temperatures for 6 months. A trained descriptive sensory panel developed a lexicon of 44 attributes to profile the aroma, flavor, and texture of porridges prepared from the flours. Grain decortication alone did not show an effect on the aroma and flavor profile of porridge. Extrusion cooking of both wholegrain and decorticated flours increased cereal-like aromas (branny, canned sweetcorn, sweet, and wheaty) and flavor (starchy), as well as stiffness and cohesiveness of the porridges. The porridges from the extruded pearl millet flours stored for up to 6 months at ambient and elevated temperatures did not show any indications of rancidity. In contrast, rancidity-associated aromas (chemical, painty, and soapy) and flavor (chemical) increased in porridges from the raw flours stored for 4 weeks and longer. These results indicate that grain decortication did not sufficiently reduce fat content to prevent oxidation, while extrusion cooking stabilized the pearl millet flours. In addition, intensified "cereal-like" aromas and flavors were probably due to Maillard reactions occurring during extrusion cooking. Resulting aroma compounds could have been immobilized in the extruded matrix and not released during flour storage. The application of extrusion cooking with a simple friction-heated single-screw extruder is a viable process for both precooking and extending the shelf life of pearl millet flours. PRACTICAL APPLICATION: This study demonstrates the potential of extrusion cooking to precook wholegrain pearl millet while preventing fat rancidity in wholegrain pearl millet flour, thereby improving the sensory quality and stability of pearl millet food products. The extensive sensory characterization of pearl millet porridge-type foods can serve as a guidance tool for development, improvement, and quality control of pearl millet foods. Furthermore, it establishes the efficacy of simple friction-heated, single-screw extruders for commercial manufacture of ready-to-eat wholegrain pearl millet food products by small and medium scale entrepreneurs.

Lipase - The fascinating dynamics of enzyme in seed storage and germination - A real challenge to pearl millet

Pearl millet is considered as 'nutri-cereal' because of high nutrient density of the seeds. The grain has limited use because of low keeping quality of the flour due to the activities of rancidity causing enzymes like lipase, lox, pox and PPO. Among all the enzymes, lipase is most notorious because of its robust nature and high activity under different conditions. we have identified 2180 putative transcripts showing homology with different variants of lipase precursor through transcriptome data mining (NCBI BioProject acc. no. PRJNA625418). Lipase plays dual role of facilitating the germination of seeds and deteriorating the quality of the pearl millet flour through hydrolytic rancidity. Different physiochemical methods like heat treatment, micro oven, hydrothermal, etc. have been developed to inhibit lipase activity in pearl millet flour. There is further need to develop improved processing technologies to inhibit the hydrolytic and oxidative rancidity in the floor with enhanced shelf-life.

Effect of Fermentation on Nutritional Quality, Growth and Hematological Parameters of Rats Fed Sorghum-Soybean-Orange flesh Sweet Potato Complementary Diet

The protein quality of complementary foods developed from fermented and unfermented sorghum, soybeans, and orange-fleshed sweet potato (OFSP) flour blends was evaluated using rat model. The test diet was as follows: UF2: unfermented sorghum (56%), soybean (17%), and OFSP (27%); UF3: unfermented sorghum (59%), soybean (31%), and OFSP (10%); F2: fermented sorghum (56%), soybean (17%), and OFSP (27%); and F3: fermented sorghum (59%), soybean (31%), and OFSP (10%), while cerelac served as positive control, corn starch (basal diet), and ogi (negative control). Forty-nine Wistar albino rats were grouped and fed with diets for 28 days. The growth, hematological, serum parameters of animals, protein quality, and proximate composition of developed diet were determined. Fermentation significantly improved the protein content and nutritional indices of experimental animals. Moisture content ranged from 2.5% to 9.24%, protein (7.09%-25.29%), ash (1.09%-3.71%), fat (10.28%-15.24%), and fiber (0.85%-3.17%). The biological values (BV) ranged from 75.11% to 78.44%. The weight gained in rat fed the formulated diet ranged from 46.0 g to 77.3 g and was highest in F3. The packed cell volume (PCV), hemoglobin concentration (HBC), red blood cell (RBC), and lymphocytes were highest in F3. Urea nitrogen and creatinine of the rats fed with formulated diets ranged from 3.58 to 15.32 mg/dl and 1.56 to 6.15 mg/dl, respectively. Sample F3 is a protein-rich complementary food that is comparable to ogi and suitable to manage malnutrition and support growth in children. However, clinical trials on the formulated diet are needed to further substantiate its nutritional potentials.

Millet: A review of its nutritional and functional changes during processing

Millets are a major source of human food, and their production has been steadily increasing in the last decades to meet the dietary requirements of the increasing world population. Millets are an excellent source of all essential nutrients like protein, carbohydrates, fat, minerals, vitamins, and bioactive compounds. However, the nutrients, bioactive compounds, and functions of cereal grains can be influenced by the food preparation techniques such as decortication/dehulling, soaking, germination/malting, milling, fermentation, etc. This study discusses the nutritional and functional changes in millet during different traditional/modern processing techniques, based on more than 100 articles between 2013 and 2020 from Web of Science, Google Scholar, FAO, and USDA databases. Our results concluded that processing techniques could be useful to combat undernourishment and other health issues. Moreover, this review provides detailed information about millet processing, which is advantageous for industry, consumers, and researchers in this area.

Physicochemical and sensory qualities of complemenatry meal made from sprouted and unsprouted sorghum, Irish potato and groundnut

Weaning food was produced from the blends of sprouted and unsprouted sorghum-Irish potato, and groundnut flour. In the developed weaning foods, moisture content ranged from 8.44% to 12.70%, crude protein (7.40%-14.53%) crude ash (1.53%-1.77%), crude fiber (6.65%-6.88%), crude fat (3.31%-3.73%) and carbohydrate content (65.10%-69.15%). Sprouting and protein supplementation with groundnut improved the protein content of the formulated meals with values comparable to commercial sample (cereals). Mineral content reduced with sprouting, whereas the addition of Irish potato and groundnut increased the mineral content. Calcium ranged from 91.00% to 121.33% and potassium (487.33%-956.67%). Sample NSIG2 had the highest potassium. Tannin ranged from 0.11 to 0.64 mg/100 g; phytate (4.98-7.42 mg/100 g); and oxalate (0.36-0.98 mg/100 g). Peak viscosity ranged from 43.08 to 23.57 RVU, trough (41.08-22.50 RVU), breakdown viscosity (61-14), final viscosity (84.33-52.53 RVU), setback viscosity (41.33-89.00 RVU), and peak time (5.07-7.00) in both the sprouted and unsprouted sorghum-irish potato-groundnut flour, respectively. The pasting temperature of the weaning food blends ranged between 87.25 and 89.60°C with SIG0 and NSIG2 having the lowest and highest values, respectively. The study showed that complementary food products formulated from this locally available food commodities is a promising food and has good nutritive value.