Tannin-free Sorghum Research Articles

Germinated sorghum (Sorghum bicolor L.) and seedlings show expressive contents of putrescine

Free bioactive amines were quantified during germination of tannin and tannin-free sorghum seeds (8 genotypes) and seedlings (2 genotypes). Among the ten amines investigated, three (putrescine, spermidine and spermine) were found. Tannin-free sorghum seeds had higher levels of spermidine, spermine, putrescine and total amines (1.28, 1.27, 0.35, 2.91 mg/100 g dwb, respectively), compared to tannin sorghum (0.91, 1.13, 0.06, 2.09 mg/100 g dwb, respectively). Throughout germination, in all seedling parts, putrescine was prevalent followed by spermidine. Spermine was only detected in the 7th germination day in the cotyledon and radicle of tannin sorghum. In the cotyledon, putrescine levels increased (24- and 30- fold for tannin and tannin-free sorghum, respectively). Spermine decreased, but it increased reaching initial levels (∼1 mg/100 g dwb) in two tannin-free genotypes. Spermidine changes were not significant. Germinated sorghum was characterized by high putrescine and low spermidine levels, with higher levels for tannin-free (29.55 mg/100 g putrescine; 2.79 mg/100 g spermidine) compared to tannin (24.41 mg/100 g putrescine, 1.40 mg/100 g spermidine) sorghums. Different from other seeds, germinated sorghum is rich in putrescine. By selecting the proper genotype one can modulate polyamine contents in germinated sorghum, thereby obtaining different profile of amines for specific food application.

The effect of Zimbabwean tannin-free sorghum flour substitution on fine dried noodles quality characteristics

Sorghum crop is a food-security cereal crop of enormous importance in numerous parts across the whole world. To assess the effect of Zimbabwean Macia sorghum on fine dried noodles characteristics, composite flours comprising 10%, 20%, and 30% sorghum were investigated for their physicochemical composition, dough rheological parameters, and sensory analysis of the final dried noodles. Sorghum addition (10%–30%) resulted in a significant decrease in the protein and moisture content while it increased fat and ash content. With the increase of sorghum content, peak viscosity, trough viscosity, final viscosity demonstrated an upward trend. Starch pasting properties and the gluten network are key in the determination of the hardness of noodles. Hardness (r = 0.860) and Chewiness (r = 0.862) were positively correlated with protein content. Chewiness had a negative correlation with fat (r = -0.893) and ash (r = -0.899). As the amount of sorghum added increases, the color of the fine dried noodles becomes grayer. The existence of polyphenol oxidase enzymes and a higher amount of ash may be related to noodle discoloration. In the sensory evaluation, the total score of fine dried noodles added with 10% sorghum was not significantly different from that of the control group. Increasing the sorghum proportion had adverse effects although noodles produced were still acceptable.

Heterosis and combining ability for yield and resistance to grain mold in tannin-free photoperiod-insensitive sorghum [Sorghum bicolor (L) Moench] in Senegal

Heterosis and combining ability for yield and resistance to grain mold in tannin-free photoperiod-insensitive sorghum [Sorghum bicolor (L) Moench] in Senegal

Effect of extrusion and turmeric addition on phenolic compounds and kafirin properties in tannin and tannin-free sorghum

Sorghum is a potential substitute for corn/wheat in cereal-based extruded products. Despite agronomic advantages and its rich diversity of phenolic compounds, sorghum kafirins group together and form complex with tannins, leading to a low digestibility. Phenolic content/profile by UPLC-ESI-QTOF-MSE and kafirins polymerization by SE-HPLC were evaluated in wholemeal sorghum extrudates; tannin-rich (#SC319) and tannin-free (#BRS330) genotypes with/without turmeric powder. Total phenolic, proantocyanidin and flavonoid contents were strongly correlated with antioxidant capacity (r > 0.9, p < 0.05). Extrusion increased free (+60%) and decreased bound phenolics (−40%) in #SC319, but reduced both (−40%; −90%, respectively) in #BRS330, which presented lower abundance after extrusion. Turmeric addition did not significantly impact antioxidant activity, phenolic content and profile and kafirins profile. Tannins presence/absence impacted phenolic profiles and polymerization of kafirins which appears related to the thermoplastic process. The extrusion improved proteins solubility and can positively enhance their digestibility (phenolic compounds-proteins interactions), making more accessible to proteolysis in sorghum extrudates.

Water stress increased the flavonoid content in tannin-free sorghum grains

The effect of water stress on the profile of flavonoids was evaluated in three tannin-containing (SC115, SC60, and SC720) and in three tannin-free (B.Tx635, SA 5330-MARTIN, and SC373) sorghum genotypes. Flavones, flavanones and 3-deoxyanthocyanidins were analyzed by high-performance liquid chromatography with diode array detection. The water stress x genotype interaction increased the sorghum flavones (ranging from 11.3–85.5 μg/g), flavanones (0.14–157.2 μg/g) and 3-deoxyanthocyanidins (5.2–245.3 μg/g) content. The effect of water stress on 3-deoxyanthocyanidins was related to the presence of tannin in sorghum genotypes. Water stress increased the functional potential of sorghum, especially in tannin-free genotypes, by increasing the flavone, flavanone and 3-deoxyanthocyanidin content.

Retention of phenolic compounds and acceptability of gluten-free churros made with tannin or tannin-free sorghum flour

Abstract: The objective of this work was to evaluate the acceptability of gluten-free churros made either with tannin or tannin-free sorghum flour, as well as the retention of their phenolic compounds and antioxidant capacity retention after cooking and frying. The churros were developed by replacing wheat flour with sorghum flour from the sorghum cultivars BRS 305 with tannin (T-churro) or BRS 501 tannin free (TF-churro). The content of phenolic compounds and antioxidant activity were evaluated before and after the thermal processing. Both products had a high acceptability (84.5‒95.5%) for all evaluated sensory attributes, and no difference was observed for color, aroma, and flavor. However, the T-churro showed a higher acceptance for texture, overall acceptability, and purchase intention. The churros had a similar proximate composition for fiber content. The phenol content was about three times and antioxidant activity about 20 times higher for T-churro than for TF-churro. Although subjected to two types of processing (cooking and frying), the fried and ready-to-eat T-churro retained more than 50% of anthocyanins, phenols, and antioxidant activity. The TF-churro product showed a retention of these compounds above 70, 40, and 65%, respectively. The tannin content of 'BRS 305' sorghum increases its functional potential and does not negatively affect the acceptability of the churros. Sorghum either with or without tannins has the potential to be used for the production of gluten-free churros.

Using sweet sorghum bagasse for production of amylases required for its grain hydrolysis via a biorefinery platform

Sweet sorghum plant, a widely grown energy crop, was utilized through a biorefinery process, by which its grains were hydrolyzed by the crude amylases produced from its bagasse. The hemicellulosic part of the bagasse was hydrolyzed with 0.5–1.0% sulfuric acid at 140–180 °C for 30–60 min and applied for amylase production using halotolerant bacterium Nesterenkonia sp. strain F. In the hydrolysate obtained at 140 °C for 60 min using 1% acid, Nesterenkonia showed 73.3 U/mL amylase activity by the consumption of 16.2 g/L xylose and 8.3 g/L other sugars. Supplementation of the hydrolysates with sorghum grain resulted in 38–67% higher amylase production. Furthermore, addition of biocompatible surfactants of Tween 20 and Tween 80 (0.1 g/L) increased the activity to 93 and 97 U/mL, respectively. The resulting crude enzyme was used in the process of ethanol production from both tannin-containing and tannin-free sorghum grains (6%), leading to 17.7 and 17.0 g/L bioethanol production, respectively. Through the cultivation of Nesterenkonia on the hemicellulosic hydrolysates, 5–10 g/L volatile fatty acids (VFA), 0.36–0.69 g/L acetone-butanol-ethanol (ABE), and 468–721 mg/L single cell protein (SCP) were also produced. The obtained SCP contained most of the essential amino acids and relatively high amounts of phenylalanine (8%), threonine (7%), methionine (6%), and lysine (6%).

A low calorie and nutritive sorghum powdered drink mix: Influence of tannin on the sensorial and functional properties

Sorghum tannins are excellent antioxidants and may contribute to the health although their astringency is believed to be objectionable. This work aims to develop a low calorie and nutritive powdered drink mix with tannin-sorghum (PDT-3670) and tannin-free sorghum (PDTF-7064) extruded flours and to evaluate their sensorial, nutritional and functional properties. Both products were accepted on all attributes with acceptance from 70.9 to 93.2%. PDT-3670 had greater purchase intention than PDTF-7064 and better acceptability for flavor and overall acceptability. There was no difference in the aroma, texture and color acceptability between the two products. The antioxidant activity, phenols, tannins and anthocyanin contents were higher in the PDT-3670 powdered drink, having potential functional properties. Chemical analyzes indicated that both powdered formulates may be potential sources of fiber (7.9–9.1 g/100 g) and proteins (18.5 g/100 g). The serving size dissolved in water had 126.5–128.3 kcal and dissolved in milk 214–215.18 kcal. The tannin did not negatively influence the acceptance of drinks, and improved their functional properties. This nutritive and low calorie sorghum powdered drink mix has potential to be introduced, especially, into the gluten-free food market and can bring health benefits to the consumers.

Effect of Sorghum Based Nutritional Programs on Performance, Carcass Yield and Composition of Breast in Broilers

ABSTRACT An experiment was conducted to compare three nutritional programs, which were developed with tannin-free grain sorghum based diets, evaluating performance, carcass yield and bromatological composition of the pectoral muscle of broilers. A total 1360 chicks mixed (50:50), from one to 42 days old Hubbard Flex Broilers, were housed in a completely randomized design consisting of treatments and 10 replicates each, distributed as follows: three programs with whole sorghum grain based diets (nutritional program with daily adjustment, nutritional program with every three days adjustment and nutritional program with four stages and a program with ground and whole sorghum grain based feed (four stages). The cumulative performance was evaluated at, 21 and 42 days, determining feed intake, weight gain, feed conversion and viability. At 42 days, the yield of eviscerated carcass, breast (full and boneless), thighs/drumsticks and wings and breast composition were evaluated. Nutritional adjustments showed better feed conversion, did not affect the carcass, commercial cuts yield and had a good breast meat quality. It can be concluded that daily feed programs could be performed in poultry industry with the mixture of whole sorghum grains and concentrates directly on farms contributing to better logistics and feed transportation cost.

Effects of replacing corn with sorghum on the performance of overfed mule ducks

The aim of this trial was to study the effects of replacing yellow corn (C) with condensed tannin-free sorghum (S) during the finishing period (F period; age 53 to 79 d) and/or overfeeding period (O period; age 80 to 91 d) on the performance of overfed mule ducks. 192 ducks were divided into 4 groups (48 in each) differing in the cereal (yellow corn or sorghum) included in the diet given during the F and/or the O periods, using a 2 × 2 factorial arrangement of treatments : SS, SC, CS, CC. At the end of the O period, the birds were slaughtered after 10 h of fasting to measure foie gras and magret qualities. Mortality (1%; P > 0.05) and weight gain (2,030 g; P > 0.05) during the O period were similar in the 4 groups. At the end of the O period, birds overfed with sorghum had foie gras that was heavier (723 vs. 694 g in CS+SS vs. CC+SC, respectively; P < 0.05) and less yellow (24.40 vs. 38.59 for b* in CS+SS vs. CC+SC, respectively; P < 0.001) than birds overfed with corn. Fat loss during foie gras cooking was similar in the 4 groups (18%; P > 0.05), but the foie gras was less yellow in birds overfed with sorghum (14.84 vs. 26.01 for b* in CS+SS vs. CC+SC, respectively; P < 0.001). Weight of magret was similar in the 4 groups (491 g, P > 0.05) but the color of the breast muscle and skin of magret was less yellow in birds overfed with sorghum compared with corn (12.26 vs. 12.92 and 13.84 vs. 18.30 in CS+SS vs. CC+SC, respectively; P < 0.001). In conclusion, the replacement of yellow corn with sorghum during finishing and/or overfeeding is possible and useful in a mule duck foie gras production system because it increases foie gras weight without decreasing the weight of magret. However, it changes the quality of the products, mainly their color.

Use of whole grain and refined flour from tannin and non-tannin sorghum (Sorghum bicolor (L.) Moench) varieties in frybread

Frybreads were prepared using wheat flour and wheat-sorghum composite flours (refined and whole grain; white, tannin-free and red, tannin-containing) at 0, 25, 50, and 75% sorghum flour. Hardness, volume, specific volume, color, and oil uptake were determined. Frybreads made with refined white, tannin-free sorghum were also evaluated in a sensory panel. Substitution of sorghum flour for wheat flour reduced the volume and increased the darkness of the fried dough pieces compared with wheat flour controls. Oil absorption was unaffected when using white, tannin-free sorghum. When using red, tannin-containing sorghum, oil absorption increased for refined flour and decreased for whole grain flour, suggesting that a component only present in the whole grain tannin-containing Sorghum--perhaps tannins themselves--may decrease oil uptake. Panelists rated frybreads containing up to 50% white, tannin-free sorghum flour as not significantly different from control frybreads made with refined wheat flour.

Effect of Dilute Alkaline Steeping on the Microbial Contamination, Toxicity and Diastatic Power of Sorghum Malt

Steeping in dilute alkali was investigated with the primary aim of reducing the moulds, coliforms, and preventing toxicity of sorghum malt. Red tannin-free sorghum cultivars NK 283 and PAN 8546 were steeped in 0.1, 0.2 and 0.3% NaOH and 0.1, 0.3 and 0.5% Ca(OH)2. The effects of these solutions on aerobic plate count, lactic acid bacteria, yeasts, moulds, coliforms, the presence of some mycotoxins (aflatoxins, fumonisins, deoxynivalenol and zearalenone), the cytotoxicity and diastatic power (DP) of sorghum malt was evaluated. Steeping NK 283 in 0.1% Ca(OH)2 increased the DP from 10.5 to 16 Sorghum Diastatic Units (SDU)/g. However, it did not reduce the general levels of malt microflora. Steeping in dilute NaOH reduced the microflora on the malt. Steeping both grain cultivars with 0.2% NaOH resulted in malts with the moulds and coliforms reduced to approximately 3.5 and 2.0 log colony forming units/g, respectively and the percentages of some mould species to very low or undetectable levels. The DP of the 0.2% NaOH steeped malts increased to 16.2 and 26.9 SDU/g in the NK 283 and PAN 8546, respectively. There were no detectable amounts of mycotoxins and no indication of cytotoxicity in the 0.2% NaOH steeped samples. Steeping sorghum grains in food-grade 0.2% NaOH is recommended as a method for the control of bacterial and fungal contamination during sorghum malting.

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds, phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.

Effect of Chemical Treatments on Polyphenols and Malt Quality in Sorghum

Tannin-containing sorghums, Chirimaugute and DC-75, and a tannin-free sorghum, SV2, were steeped in water, HCl (0·25 m), formaldehyde (0·017 m) and NaOH (0·075 m) for 8 and 24 h. Germination was carried out for 2 and 5 d. Steeping in NaOH enhanced water uptake of the grains compared with the other treatments. All treatments reduced the polyphenol content of the raw grain. Treatment with NaOH or formaldehyde (HCHO) was more effective than water or HCl. Malt quality was measured in terms of diastatic power (DP). Potential DP, determined after the peptone extraction, indicated higher amylase activity in DC-75 malt than in Chirimaugute and SV2 malt. Available DP, determined after water extraction, was low in malt from the tannin-containing varieties that had been treated with water or HCl. Malting alone was not an effective method of reducing the enzyme inhibitory power of the sorghum tannins. Available DP was markedly improved by the NaOH and HCHO treatments of the tannin-containing varieties. It is concluded that steeping in dilute NaOH is effective in detoxifying high-tannin sorghums, reducing the steeping period and enhancing malt quality. Steeping in NaOH appears to be a safer alternative to HCHO for treatment of high-tannin sorghums in the malting industry and for other food uses.

EFFECT OF ALKALINE STEEPING ON WATER UPTAKE AND MALT QUALITY IN SORGHUM

Condensed tannin-free and high-tannin sorghum grain were steeped in dilute alkali and the effects on water uptake during steeping and final malt quality were determined. With the condensed tannin-free sorghum, steeping in dilute alkali led to increased water uptake during steeping and an improvement in malt quality in terms of diastatic power and free amino nitrogen. These effects are presumed to be due to the alkali opening up the pericarp cell wall structure of the grain, allowing more rapid water uptake. Best results were obtained by application of alkali early in steeping, presumably because the grain is less susceptible to alkali toxicity than later in steeping. Steeping high-tannin sorghum in dilute alkali did not improve malt quality. This appeared to be because water uptake was not increased to the same extent as with condensed tannin-free sorghum, as the alkali reacted with the tannins.

Toxic effects of fermented and unfermented sorghum meal diets naturally contaminated with mycotoxins.

Male weanling rats fed diets containing fermented and unfermented tannin-free sorghum meals naturally contaminated with traces of ochratoxin A, zearalenone, and an unidentified toxic substance developed anorexia. Mean changes in body weight over a 28-day feeding period for rats fed fermented and unfermented sorghum meal and ANCR casein diets of 8% protein were -2.8, +13.8, and +100.5 g, respectively. Rats fed fermented sorghum meal developed alopecia; hematological findings showed a decreased mean corpuscular volume, hypochromic microcytosis, balanced leukopenia, and hypoproteinuria . Histological findings showed testicular hypoplasia of the germinal epithelium and no mature spermatozoa. Necrosis and mineralization in Henle's loop were also observed. No damage was apparent to the liver, cerebellum, cerebrum, spleen, or adrenal glands.