Effects of phenolics in sorghum grain on its bitterness,astringency and other sensory properties

Despite the fact that condensed tannins are potentially important antioxidants, there is a general belief that tannins in sorghum confer objectionable sensory attributes. The objective of this study was to determine differences in the sensory attributes of sorghums containing different levels of total phenolic compounds. A trained sensory panel described and quantified the sensory attributes of different sorghums (condensed‐tannin containing and tannin‐free). All the sorghum cultivars were perceived as bitter and astringent. Bran infusions of tannin sorghums were perceived as darker, clearer, more bitter and more astringent than those of the tannin‐free sorghums, while those of tannin‐free sorghums were perceived as sweeter and cloudy. Sorghum whole‐grain rice from the tannin sorghums which had relatively soft endosperm texture (PAN 3860 and Ex Nola 97 GH) was perceived as dark, hard, chewy, bitter and astringent, while that from tannin‐free sorghums having relatively hard endosperm texture (Segaolane and Phofu) was perceived as soft, sweet and had a maize‐flavour. Surprisingly, the bitterness and astringency, as well as other sensory attributes of NS 5511 (tannin sorghum), were perceived as similar to PAN 8564 (tannin‐free sorghum) even though NS 5511 had more than twice the total phenol content of PAN 8564. This suggests not all condensed‐tannin containing sorghums have objectionable sensory attributes. Copyright © 2007 Society of Chemical Industry     

Current research developments on polyphenolics of rapeseed/canola: a review

The utilization of rapeseed/canola as a source of food-grade proteins is still limited due the presence of glucosinolates, phytates, hulls and phenolics. Phenolic acids and condensed tannins are the predominant phenolic compounds found in rapeseed. The content of phenolic compounds in rapeseed/canola products is much higher than that found in corresponding products from other oleaginous seeds. Phenolics such as free phenolic acids, sinapines and condensed tannins may contribute to the bitter taste and astringency of rapeseed products. In addition, both phenolic acids and condensed tannins may form complexes with proteins, thus lowering the nutritional value of rapeseed products. The specific mode of interaction of rapeseed phenolics with proteins is still not well understood. Therefore, a better knowledge of factors which influence the interactions between phenolics and proteins would be beneficial in developing more efficient technologies for production of phenolic-free rapeseed protein isolates.     

125th Anniversary Review: The science of the tropical cereals sorghum,maize and rice in relation to lager beer brewing

Mainstream lager beer brewing using the tropical cereals sorghum, maize and rice, either as malt or as raw grain plus commercial enzymes, is becoming widespread. This review examines the differences in composition between these tropical cereals and barley and their impact on brewing processes and beer quality. All of these cereals have a starch gelatinization temperature some 10 °C higher than barley. The sorghum prolamin proteins are particularly resistant to proteolysis owing to disulphide cross‐linking involving γ‐kafirin. Unlike barley, the major endosperm cell wall components in sorghum and maize are arabinoxylans, which persist during malting. The rice cell walls also seem to contain pectic substances. Notably, certain sorghum varieties, the tannin‐type sorghums, contain considerable levels of condensed tannins (proanthocyanidins), which can substantially inhibit amylases, and probably also other brewing enzymes. Tropical cereal malts exhibit a similar complement of enzymic activities to barley malt, with the notable exception of β‐amylase, which is much lower and essentially is absent in their raw grain. Concerning beer flavour, it is probable that condensed tannins, where present in sorghum, could contribute to bitterness and astringency. The compound 2‐acetyl‐1‐pyrroline, responsible for the popcorn aroma of maize and also the major aroma compound in rice, presumably affects beer flavour. However, much more research is needed into tropical cereals and beer flavour. Other future directions should include improving hydrolysis of prolamins into free amino nitrogen, possibly using prolyl carboxypeptidases and investigating tropical cereal lines with useful novel traits such as high amylopectin, high protein digestibility and low phytate. Copyright © 2013 The Institute of Brewing & Distilling     

Tannin analysis of food products

Phenolic substances occur primarily in fruits and vegetables and in the seeds of certain pigmented cultivars of sorghum, millets, and legumes. One of the major difficulties encountered in polyphenol research is the lack of a standard quantitative method for the analysis of phenolics that would be suitable for a wide range of seeds, forage crops, and food products and under a variety of experimental conditions. Some methods measure "total phenol", which may not be a true index of the nutritional quality of foods and thus does not distinguish polyphenols of nutritional concern from other low-molecular-weight phenols that also occur naturally in these products. Tannic acid (a hydrolyzable gallotannin) is commonly used as a "reference standard", but this may be a questionable practice since its biological properties differ from those of tannins of flavonoid origin. Polyphenols of cereals and legumes are predominantly of the latter type. Also, commercially available tannic acid has been shown to be a mixture of four phenolic compounds, the relative proportions of which vary with the samples. Thus, the choice of a suitable standard for tannin analysis is also important. The quantitative extraction of the condensed tannins from plant tissue is always difficult, since it may be complexed to a carbohydrate or protein matrix which could be quite insoluble due to a high degree of polymerization. The literature on tannin methodology is diverse and at times conflicting. Currently available methods for tannin analysis range from simple colorimetric, UV spectrophotometric, chromatographic, and enzymic to more sophisticated and expensive nuclear magnetic resonance (NMR) techniques. None of these methods of analyses is completely satisfactory nor can it be applied to different food products with the same degree of success. This review covers physical and chemical methods for tannin analysis of different food products, the problems in analysis and interpretation of data, and future research needs in this area.     

Sorghum Grain: From Genotype,Nutrition, and Phenolic Profile to Its Health Benefits and Food Applications

Globally, sorghum is one of the most important but least utilized staple crops. Sorghum grain is a rich source of nutrients and health‐beneficial phenolic compounds. The phenolic profile of sorghum is exceptionally unique and more abundant and diverse than other common cereal grains. The phenolic compounds in sorghum are mainly composed of phenolic acids, 3‐deoxyanthocyanidins, and condensed tannins. Studies have shown that sorghum phenolic compounds have potent antioxidant activity in vitro, and consumption of sorghum whole grain may improve gut health and reduce the risks of chronic diseases. Recently, sorghum grain has been used to develop functional foods and beverages, and as an ingredient incorporated into other foods. Moreover, the phenolic compounds, 3‐deoxyanthocyanidins, and condensed tannins can be isolated and used as promising natural multifunctional additives in broad food applications. The objective of this review is to provide a comprehensive understanding of nutrition and phenolic compounds derived from sorghum and their related health effects, and demonstrate the potential for incorporation of sorghum in food systems as a functional component and food additive to improve food quality, safety, and health functions.     

Sorghum (Sorghum bicolor L.): Nutrients,bioactive compounds,and potential impact on human health

Sorghum is the fifth most produced cereal in the world and is a source of nutrients and bioactive compounds for the human diet. We summarize the recent findings concerning the nutrients and bioactive compounds of sorghum and its potential impact on human health, analyzing the limitations and positive points of the studies and proposing directions for future research. Sorghum is basically composed of starch, which is more slowly digested than that of other cereals, has low digestibility proteins and unsaturated lipids, and is a source of some minerals and vitamins. Furthermore, most sorghum varieties are rich in phenolic compounds, especially 3-deoxyanthocyanidins and tannins. The results obtained in vitro and in animals have shown that phenolics compounds and fat soluble compounds (polycosanols) isolated from sorghum benefit the gut microbiota and parameters related to obesity, oxidative stress, inflammation, diabetes, dyslipidemia, cancer, and hypertension. The effects of whole sorghum and its fractions on human health need to be evaluated. In conclusion, sorghum is a source of nutrients and bioactive compounds, especially 3-deoxyanthocyanidins, tannins, and polycosanols, which beneficially modulate, in vitro and in animals, parameters related to noncommunicable diseases. Studies should be conducted to evaluate the effects of different processing on protein and starch digestibility of sorghum as well as on the profile and bioavailability of its bioactive compounds, especially 3-deoxyanthocyanidins and tannins. Furthermore, the benefits resulting from the interaction of bioactive compounds in sorghum and human microbiota should be studied.     

Changes in tannin content,polymerisation and protein precipitation capacity in oak (Quercus incana) leaves with maturity

Changes in the content of total phenolics, condensed tannins, proanthocyanidins and flavan-4-ols, the degree of polymerisation, the protein precipitation capacity, the protein-precipitable phenolic content and the specific activity (protein: tannin in the complex) were determined in Quercus incana leaves with maturity. Total phenolic content and protein precipitation capacity decreased whereas the levels of condensed tannins, proanthocyanidins, flavan-4-ols and degree of polymerisation increased with maturation. The protein-precipitable phenolic content was highest in young leaves and decreased as leaves matured. The specific activity decreased slightly. The results suggest that young leaves would be more toxic to livestock than mature leaves.     

Contribution of tomato phenolics to suppression of COX-2 expression in KB cells

Tomatoes, which are consumed worldwide, contain abundant phenolics. The objective of this study was to understand the suppression effect of phenolics in fresh and heated tomatoes on the expression of cyclooxygenase 2 (COX-2). Both small and big tomatoes of fresh or heated (in boiling water for 30 min) treatments were used. Sephadex LH-20 gel was used to separate the noncondensed tannin containing and the condensed tannin containing fractions from the crude phenolic extracts of tomatoes. The condensed tannin containing fraction was rich in condensed tannins and simple phenolics. The noncondensed tannin containing fraction contained abundant nontannin flavans. This study explored the effect of tomato phenolic extracts on the regulation of 12-o-teradecanoylphorbol-13-acetate (TPA)-induced inflammatory responses in KB cells. HPLC showed that tomato phenolic profiles were similar between small and big tomatoes either by fresh or heated treatment. Fresh tomato extracts had 70.8 +/- 4.8% (mean +/- SD) noncondensed tannin containing polyphenols (6.68 +/- 0.09 mg/g dry weight), 27.4 +/- 6.9% condensed tannin containing polyphenols (3.52 +/- 0.24 mg/g dry weight), and 1.7 +/- 0.6% other residues. Instead, heated tomato had 53.3 +/- 4.3% noncondensed tannin containing polyphenols (2.70 +/- 0.20 mg/g dry weight), 24.2 +/- 1.7% condensed tannin containing polyphenols (7.37 +/- 0.03 mg/g dry weight), and 22.5 +/- 4.8% other residues. Cell studies showed that phenolic extracts of heated tomatoes resulted in increased suppression of COX-2 expression compared with that of fresh tomato. Noncondensed tannin containing fraction of fresh tomato greatly suppressed COX-2 expression (P < 0.05) that compared to the negative control, but both noncondensed tannin containing and condensed tannin containing fractions of heated tomatoes showed suppression on COX-2 expression. These results suggest that tomato phenolics may play an important role in the chemoprevention of cancer.     

Effect of adding an anaerobic fungal culture isolated from a wild blue bull (Boselophus tragocamelus) to rumen fluid from buffaloes on in vitro fibrolytic enzyme activity,fermentation and degradation of tannins and tannin‐containing Kachnar tree (Bauhinia variegata) leaves and wheat straw

The study investigated the effects of adding an anaerobic fungus (Piromyces sp FNG5; isolated from the faeces of a wild blue bull) to the rumen fluid of buffaloes consuming a basal diet of wheat straw and concentrates on in vitro enzyme activities, fermentation and degradation of tannins and tannin‐rich tree leaves and wheat straw. In experiment 1, strained rumen fluid was incubated for 24 and 48 h, in quadruplicate, with or without fungal culture using condensed tannin‐rich Bauhinia variegata leaves as substrates. In experiment 2, in vitro incubation medium containing wheat straw and different concentrations of added tannic acid (0–1.2 mg mL^?1) were incubated for 48 h, in quadruplicate, with strained buffalo rumen fluid with or without fungal culture. In experiment 3, tolerance of the fungal isolate to tannic acid was tested by estimating fungal growth in pure culture medium containing different concentrations (0–50 g L^?1) of tannic acid. In in vitro studies with Bauhinia variegata tree leaves, addition of the fungal isolate to buffalo strained rumen liquor resulted in significant (P < 0.01) increase in neutral detergent fibre (NDF) digestibility and activities of carboxymethyl cellulase (P < 0.05) and xylanase (P < 0.05) at 24 h fermentation. There was 12.35% increase (P < 0.01) in condensed tannin (CT) degradation on addition of the fungal isolate at 48 h fermentation. In in vitro studies with wheat straw, addition of the fungus caused an increase in apparent digestibility (P < 0.01), true digestibility (P < 0.05), NDF digestibility (P < 0.05), activities of carboxymethyl cellulase (P < 0.001), β‐glucosidase (P < 0.001), xylanase (P < 0.001), acetyl esterase (P < 0.001) and degradation of tannic acid (P < 0.05). Rumen liquor from buffaloes which had never been exposed to tannin‐containing diet had been found to have substantial inherent tannic acid‐degrading ability (degraded 55.3% of added tannic acid within 24 h of fermentation). The fungus could tolerate tannic acid concentration up to 20 g L^?1 in growth medium. The results of this study suggest that introduction of an anaerobic fungal isolate with superior lignocellulolytic activity isolated from the faeces of a wild herbivore may improve fibre digestion from tannin‐containing feeds and degradation of tannins in the rumen of buffaloes. Copyright © 2005 Society of Chemical Industry     

Phenolic composition of Flacourtia indica, Opuntia megacantha and Sclerocarya birrea

The phenolic acid composition of the peel and pulp of the fruits of Flacourtia indica (Burm. f.) Merr., Opuntia megacantha (L.) Mill and Sclerocarya birrea (A. Rich.) Hochst., from Zimbabwe, were analysed using traditional colorimetric as well as HPLC methods. The total phenolics, flavanoids and condensed tannin levels varied with species. Sclerocarya birrea pulp had the highest total phenolics, flavanoids and condensed tannins, i.e., 2262 μg GAE/g, 202 μg catechin/g and 6.0% condensed tannins, respectively. Flacourtia indica pulp contained the least total phenolics, flavanoids and condensed tannins 334 μg GAE/g, 41 μg catechin/g and 1.4%, respectively. There were no significant differences in the total phenolics between the peels and the pulps of the individual fruits. However, significant differences were noted in the flavanoids and the condensed tannins between the peels and pulps of the fruits assayed. Ferulic acid, caffeic acid and vanillic acid were the dominant phenolic acids in the three fruits. There were differences between the phenolic acids in the peels and the pulps of the fruits.     

Nutritional composition and antioxidant activity in hazelnut shells from US‐grown cultivars

The hard shell of a hazelnut is a major waste of the hazelnut industry. The chemical composition, phenolic compounds (total phenolics, tannins and condensed tannins), antioxidant activity (DPPH and ABTS free‐radical scavenging assays), and the relationships between phenolic compounds and antioxidant activities of the hazelnut shells from twelve US grown cultivars were investigated to for potential commercial development. Crude fibre accounted for over 85% of total carbohydrate. The shells contained high concentrations of phenolic compounds. Concentrations of phenolic constituents and ABTS^?+ ‐scavenging capacities were significantly higher (P > 0.05) in the Oregon cultivars than their Nebraska counterparts. There were significant positive correlations between ABTS^?+ scavenging capacities and the phenolic compounds, whereas DPPH^? ‐scavenging capacity demonstrated a weak negative correlation with ABTS^?+ scavenging capacity and the phenolics. The results suggest that hazelnut hard shell may serve as a potential source of natural antioxidants for food applications.     

Ruminal degradation of tannin‐treated legume meals

The inefficiency of protein utilisation by ruminants fed protein concentrates (based on legume meals) causes serious economic loss and environmental damage owing to their rapid hydrolysis and deamination in the rumen. Thus efforts aimed at slowing the ruminal fermentation of such feeds are needed, and recent studies have observed potentially positive effects of tannins on ruminant nutrition under certain circumstances. Tannins are a complex group of naturally occurring plant polyphenols characterised by their ability to bind with proteins. This property of tannins is considered responsible for the decreased ruminal digestibility of forages both in vivo and in vitro. Under that perspective, commercial tannic acid was added at three proportions (10, 25 and 50 g kg^?1 on a dry matter basis) to four different legume meals (horse bean, kidney bean, soybean and pea), and the effect on in situ dry matter and crude protein ruminal disappearance was assessed. The results confirmed the dose‐dependent (although not persistent after 48 h) slowing of in situ digestibility, this effect being significant at the highest tannin treatment when compared with untreated samples. Scanning electron microscopy revealed that soybean seed endosperm cell walls were protected from digestion by the ruminal microbiota, while the digestion of starch granules was relatively unaffected by tannic acid. Electrophoresis of the protein fractions confirmed the lower digestibility of tannin‐treated seeds as well as the relative lack of alteration of the electrophoretic profile of individual proteins. Implications for the digestion of concentrates in ruminants are discussed. Copyright © 2004 Society of Chemical Industry     

高粱醇溶蛋白结构与功能活性的研究进展

高粱醇溶蛋白是高粱中的主要贮藏蛋白,可应用于食品加工和医疗保健领域。从高粱醇溶蛋白组成、结构和功能及活性方面进行了阐述,综述了高粱醇溶蛋白在运输生物活性成分、制备包装薄膜、改善高粱蛋白消化率、生产无麸质面团、制备生物活性肽等领域的研究现状,并对其发展前景进行了展望。研究综述为高粱醇溶蛋白在食品领域的开发和应用提供了参考。     

Characterisation of Leucaena condensed tannins by size and protein precipitation capacity

The ability of differently sized condensed tannins from the genus Leucaena, a fodder tree‐legume, to bind protein at different pH values was evaluated to characterise their potential biological effects. Two factors affecting the ability of condensed tannin to bind protein, its major biological activity, have been purported to be the condensed tannin size and the pH of the reaction environment. To test these hypotheses, the protein‐precipitating capacities of condensed tannin extracted from four Leucaena genotypes, L leucocephala (UHK636), L pallida (CQ3439), L trichandra (CPI46568) and L collinsii (OFI52/88), were assessed. Condensed tannin from L leucocephala had approximately 50% of the ability to precipitate protein on a g g^?1 basis than L pallida or L trichandra, while L collinsii gave no measurable ability to precipitate protein (reaction environment pH 5.0). Increasing or decreasing the pH of the reaction solution away from pH 5.0 (approximately the isoelectric point of the protein) reduced the ability of condensed tannin from all the species to precipitate protein, the decrease being higher at pH 2.5 than at pH 7.5. Condensed tannins from each Leucaena species were also separated by size exclusion chromatography, and the fractions examined for protein‐precipitating capacity. In general, it was found that the larger‐sized condensed tannin of the accessions L pallida and L trichandra could precipitate more protein than the smaller‐sized condensed tannin. This pattern was not found for L leucocephala. © 2001 Society of Chemical Industry.     

Impact of Processing Parameters on the Phenolic Profile of Wines Produced from Hybrid Red Grapes Maréchal Foch,Corot noir,and Marquette

Phenolic extraction in hybrid and interspecific wine grape cultivars is poorly understood, especially in terms of the impact of fermentation and enological conditions on condensed tannins and anthocyanins. Following fractionation via solid‐phase extraction and high‐performance liquid chromatography, phenolic profiles of must and wine from red hybrid grape cultivars Maréchal Foch, Corot noir, and Marquette were examined to assess the impact of enzyme and tannin addition, cold soak, and hot press during vinification. Across cultivars, hot press treatments resulted in the greatest extraction of condensed tannin, anthocyanin, and other monomeric phenolic compounds in musts, and treatments that increased skin contact time or cellular degradation during fermentation produced higher concentrations of tannins, anthocyanins, and flavonols. However, these increases were transient, evincing incomplete carryover into finished wines. Depending on initial must extraction, diglucoside forms of anthocyanins were either selectively extracted or selectively retained throughout fermentation when compared to their monoglucoside counterparts. Typical of hybrid grapes, tannin concentrations across cultivars were low, even under hot press conditions. For condensed tannins and anthocyanins, a cultivar‐specific, stable‐state concentration and phenolic profile emerged regardless of fermentation conditions. Due to the high levels of diglucoside anthocyanins and low levels of condensed tannins, it is expected that the color development and profile in these wines produced from hybrid grape cultivars will be dictated by the monomeric anthocyanins and their potential role in copigmentation processes involving other monomeric phenolic species, as opposed to the formation of polymeric color pigments.     

Changes in Tannin, Free Amino Acids, Reducing Sugars, and Starch During Seed Germination of Low and High Tannin Cultivars of Sorghum

Seedling growth and changes in tannin, starch, reducing sugars, and free amino acids were determined during germination of low and high tannin seeds of sorghum. The seedling growth was markedly suppressed in high tannin seeds as compared to low tannin seeds. About 73 and 20% tannins were lost during 120 hr germination in high tannin and low tannin seeds, respectively, Accumulation of reducing sugars, free amino acids, and degradation of starch were considerably low in high tannin seeds as compared to low tannin seeds. It is suggested that tannins are responsible for retarding the seedling growth by decreasing the rate of starch and protein degradation in germinating high tannin seeds.     

Investigations on winter season Sudanese sorghum cultivars: effect of sprouting on the nutritional value

Physicochemical attributes of sorghum grains of Wad Ahmed (summer season cultivar), Abu Ragaba and Abu Kunjara (winter season cultivars) were compared. Floury endosperms characterise grains of all cultivars. Grains of Abu Ragaba and Wad Ahmed are white and Abu Kunjara are coloured. Grains were sprouted for 24, 48 and 72 h and changes in nutrients, tannin, phytic acid, protein digestibility and total and extractable minerals were studied. The nutrients and antinutients contents significantly (P ≤ 0.05) varied between cultivars. High tannin characterises Abu Ragaba and Wad Ahmed. In vitro protein digestibility of the cultivars is comparable. Contents and HCl‐extractability of Ca, P and Fe are varied. Abu Ragaba had the higher HCl‐extractability of the minerals. Sprouting changed contents of the nutrients, reduced significantly (P ≤ 0.05) tannins and phytic acid and increased digestible protein in all cultivars. Reduction of tannins was the highest in Abu Ragaba. The magnitude of reduction increased as sprouting prolonged.     

Chemical,biochemical, and biological significance of polyphenols in cereals and legumes

Polyphenols in cereals and legumes have been receiving considerable attention largely because of their adverse influence on color, flavor, and nutritional quality. These compounds belong to the flavonoid and tannin groups and are mostly located in the seed coat or pericarp of the grains. The pearl millet flavonoids have been identified as C‐glycosylflavones by the combined use of paper chromatography and UV spectroscopy. Although nontoxic, physiological and nutritional significance of these compounds occurring in high amounts in the pearl millet grain are still not clearly understood. In view of aesthetic quality, bleaching of the millet grains in acidic solution is recommended. A large proportion of current assays involves spectrophotometry of tannin or its chromogen and tannin‐protein interaction. Sorghum and legume tannins have been characterized as condensed tannins. Several factors such as plant type, age of the plant or plant parts, stage of development, and environmental conditions govern the polyphenol contents in plants. Polyphenols are known to interact with proteins and form tannin‐protein complexes leading to either inactivation of enzymes or making proteins insoluble. These are implicated in decreasing the activities of digestive enzymes, protein and amino acid availabilities, mineral uptake, vitamin metabolism, and depression of growth. Polyphenols are known to cause certain ultrastructural changes in the different parts of experimental animals. A correlation between dietary tannins and occurrence of esophageal cancer has been established. Bird resistance and seed germination in food crops have been correlated to high contents of polyphenols. The antinutritional activity of polyphenols can be reduced by removing polyphenols from the grains by chemical treatments or removing pericarp and testa by pearling. Treatment of alkaline reagents and ammonia can remove 90% of the polyphenols. Supplementation of polyphenols‐rich diet with protein can alleviate the growth‐depressing effect of polyphenols.     

Factors affecting in vitro formation of tannin-protein complexes

In interaction of condensed tannins from Desmodium intortum and Lotus pedunculatus and tannic acid (hydrolysable tannin) with salivary mucoproteins (from sheep and goats), plant leaf proteins and bovine serum albumin were evaluated. These studies were carried out over a pH range of 2-0-9-0 and different inorganic ion conditions to simulate conditions in which dietary proteins would interact with tannins in a ruminant digestive tract. Insoluble tannin-protein interactions were found at pH 4–5–5–5 for bovine serum albumin and 3–5–5–5 for plant leaf protein. The present study showed that pH alone was not the sole determinant for tannin-protein complex formation, since tannin-protein complexation was found in the pH range 6-0–6-5 when different inorganic ions were added to the solutions. Insoluble complexes were not formed with salivary proteins, although precipitation by tannic acid was achieved at 5°C. This suggests that tannins may form soluble rather than insoluble complexes with salivary proteins. It was concluded that purified F1 leaf protein (the major protei occurring in leaf tissue) ought to be used as the test protein for evaluating tannin-protein interactions for in vitro assay procedures. Using this method it was calculated that 27–43% and 19–40% of available plant protein may interact with condensed tannins from Desmodium intortum and Lotus pedunculatus, respectively.     

Biochemical profiling of Pakistani sorghum and millet varieties with special reference to anthocyanins and condensed tannins

Cereals like sorghum and millet are splendid sources of phenolics, dependent on their genetic makeup, and possess varied levels of flavonoids, flavanols, flavanones, anthocyanins, and condensed tannins. In this study, chemical composition and anthocyanin and tannin content of seven sorghum and two millet varieties were evaluated. American Association of Cereal Chemists (AACC) respective methods were used for chemical composition. Anthocyanins were determined through HPLC/UV-Vis, while condensed tannins were determined spectrophotometrically. Four anthocyanins determined included apigeninidin, kuromanin, pelargonidin, and cyanidin. Among sorghum varieties, JS-263 had the highest apigeninidin (16 µg/g). Other anthocyanins were not found in appreciable quantities. None of the anthocyanins were detected in millet varieties. Condensed tannins were highest in sorghum variety PC-1 (179.76 mg/100g) and millet variety S. Bajra-2011 (172.75 mg/100g). Two varieties, one each from sorghum and millet, were selected for extraction of bran as a separate fraction. Brans were modified by size reduction and enzymatic treatment (xylanase and cellulase). Enzymatic treatment favorably affected the extraction of phenolic compounds like anthocyanins. Sorghum and millet flour- and bran-supplemented breads were also developed and evaluated for sensory acceptability.