Characterizing Selected Sorghum Grain Varieties and Evaluating the Suitability of Their Malt Extracts for Cultivating Microbial Biomass

Microbial biomass is cultivated for different technological applications including food processing, medicine, waste management, and research. The conventional growth media used are generally expensive thus necessitating the development of more affordable alternatives. In this study, four sorghum grain varieties, SESO 1, SESO 3, Epuripur, and Eyera, and their malt extracts were characterized which is aimed at determining their suitability for growing microbial biomass. The varieties had kernel length, kernel width, kernel thickness, and thousand kernel weigh equivalent to 3.8-4.3 mm, 3.2-4.5 mm, 2.4-2.8 mm, and 12.4-20.2 g, respectively. SESO 1 and Epuripur had corneous endosperm textures whereas those of SESO 3 and Eyera were intermediate and floury, respectively. Varieties had germinative energies > 90 % and total defects < 8 %. SESO 3 had the highest ( p < 0.05 ) crude protein ( 10.8 ± 0.3 %) and dietary fiber ( 22.5 ± 0.4 %) whereas Epuripur had the highest ( p < 0.05 ) starch ( 81.6 ± 0.0 %) and crude fat ( 2.9 ± 0.1 %). There was no significant difference ( p > 0.05 ) in the ash contents ( 2.1 ± 0.0 %). The total sugars, free amino nitrogen, condensed tannins, and pH of the malt extracts were 106-116 g/L, 70-78 mg/L, 0.1-0.6 mg/mL, and 5.5-5.7, respectively. The composition of the sorghum malt extracts suggests their potential for use in cultivating microbial biomass.

The Effect of Using Biological Treatment on Microbial Growth during the Malting of Sorghum

Malting is an important industrial product with a huge market outlet. Sorghum grain carries a numerous and variable, microbial population that mainly consists of bacteria, yeasts, and filamentous fungi. Sorghum malt is heavily reliant on chemical control of moulds and coliforms. This research aimed at investigating ways of improving malt quality and safety, using starter cultures of lactic acid bacteria and yeast, during the steeping stage of malting. All the steep treatments contained a sizeable population of moulds, greater than 4logcfu/mL, at 0hrs of steeping. A 3Log decrease was recorded in the steep treatment containing only single culture of Lactobacillus plantarum All the steeping treatments achieved varying levels of anti-nutrient reduction. The Lactobacillus plantarum CLB8 steep reduced the phytate level by as much as 47% when compared to the phytate level in sorghum grain. The combined cultures of Lactobacillus plantarum CLB8 and Saccharomyces cerevisiaeCYT1 reduced the phytate content by as much as 40% when compared to the sorghum grain without treatment. When compared to the control steep, the Lactobacillus plantarum CLB8 steep improved the anti-nutrient degradation by 31%. The combined cultures of Lactobacillus plantarum CLB8 and Saccharomyces cerevisiae CYT1 reduced the phytate content by as much as 23% when compared with the control steep. The polyphenol content was reduced by about 46% in the Lactobacillus plantarum CLB8 steep and 29% in the combined cultures of Lactobacillus plantarum CLB8 and Saccharomyces cerevisiae CYT1 steep when compared to the polyphenol content in the whole sorghum grain. Only the Lactobacillus plantarum CLB8 steep had better polyphenol reduction than the control with a 9.6% reduction more than the control. It was concluded that lactic acid bacteria can be apply as a biological control organism in malting of grains.

Maize and Sorghum as Raw Materials for Brewing, a Review

Brewing is among the oldest biotechnological processes, in which barley malt and—to a lesser extent—wheat malt are used as conventional raw materials. Worldwide, 85–90% of beer production is now produced with adjuvants, with wide variations on different continents. This review proposes the use of two other cereals as raw materials in the manufacture of beer, corn and sorghum, highlighting the advantages it recommends in this regard and the disadvantages, so that they are removed in technological practice. The use of these cereals as adjuvants in brewing has been known for a long time. Recently, research has intensified regarding the use of these cereals (including in the malted form) to obtain new assortments of beer from 100% corn malt or 100% sorghum malt. There is also great interest in obtaining gluten-free beer assortments, new nonalcoholic or low-alcohol beer assortments, and beers with an increased shelf life, by complying with current food safety regulations, under which maize and sorghum can be used in manufacturing recipes.

Mineral and fibre intake of West African dwarf sheep fed boiled cocoa seed testa and sorghum malt dust in cassava root meal based diets

The study was carried out to investigate the mineral and fibre intake of Sheep fed Cocoa Seed Testa (CST) and Sorghum Malt Dust (SMD) in cassava root meal based diets. The feeding trial was conducted on the feed intake response of West African Dwarf (WAD) sheep in a completely randomized experimental design using boiled CST and SMD based-diets. A total of twenty-eight sheep were randomly allocated to 11 – 13 months of age of CST at 10, 20 and 30% levels, SMD at 10, 20 and 30% levels and a control. The experiment lasted 90 days. Data generated were computed and subjected to a one-way analysis of variance. In the trial, the Neutral Detergent Fibre (NDF), Acid Detergent Fibre (ADF), Acid Detergent Lignin (4DL), Cellulose and Hemicellulose intake increase as the level of CST increased in the diet except for animals in treatment 3 (30% inclusion of CST). Also, NDF, ADF, ADL, Cellulose and Hemicellulose increased as the level of inclusion of SMD increased in the diet except treatment 6 (30% inclusion of SMD). The NDF intake from forage decreased as the level of SMD in the diets. The mineral intake Phosphorus, Calcium, Potassium, Magnesium, Iron, Zinc and Sulphur also followed the same pattern. The mineral intake increased as the level of inclusion of ČST and SMD increased in the diet except in treatment 3 (30% inclusion of CST) and treatment 6 (30% inclusion of SMD) where the value obtained dropped. It was concluded that minerals available in the diets containing boiled Cocoa Seed Testa and Sorghum Malt Dust were significantly (p<0.05) better in their utilization by sheep that consumed boiled Sorghum Malt Dust based diets.

Nitrogen utilization by male WAD sheep fed graded levels of boiled CST and SMD based diets

The study was carried out to investigate the nitrogen utilization by male West African Dwarf (WAD) sheep fed boiled Cocoa Seed Testa (CST) and Sorghum Malt Dust (SMD)-based diets. Twenty-eight male animals were divided into seven groups with similar average initial live weight in a completely randomized design. Each group contained four animals. The trial consisted of seven dietary treatments which comprised CST at 10, 20 and 30% levels, SMD at 10, 20 and 30% levels and a control. The trial lasted for 90 days. Data generated were subjected to a one-way analysis of variance. Apparent nitrogen intake (19.41g/d) and retention (9.67g/d) were significantly (P<0.05) higher in the treatment with 20% SMD. Generally, dietary inclusion of CST and SMD improved the nitrogen intake by male WAD sheep with the best result from sheep fed 20% sorghum malt dust based diets.

Sorghum Malt Extract as a Growth Medium for Lactic Acid Bacteria Cultures: A Case of Lactobacillus plantarum MNC 21

Cultivation of lactic acid bacteria cultures is vital for research and commercial production of fermented foods. However, the conventional growth media used are generally costly. Malt extracts from four sorghum varieties (SESO 1, SESO 3, Epuripur, and Eyera) were evaluated as alternative low-cost growth media for Lactobacillus plantarum MNC 21. Saccharified sorghum malt extracts were inoculated with 4 log cfu/mL MNC 21 and incubated at 30°C for 24 h. MRS broth was the reference medium. Microbial counts, pH, titratable acidity (TA), free amino nitrogen (FAN), and total sugars were measured. Maximum microbial counts in the extracts and MRS broth were 9 and 10 log cfu/mL, respectively. Maximum growth rate in the extracts was 0.7–0.9 log cfu/mL/h and 0.8 log cfu/mL/h in MRS broth. The final pH of the extracts was 3.5–3.6, with an overall increase in TA of 1.2% in Epuripur and 0.2% in other varieties. Final pH and TA of MRS broth were 4.1 and 1.3%, respectively. Total sugars dropped by 95.2% and FAN by 2.1% in MRS broth. In contrast, total sugars and FAN dropped by 5.6–9.1% and 24.9–32.7% respectively, in the extracts. Sorghum malt extracts can be adopted as alternative low-cost growth media for lactic acid bacteria cultures.

Application of refrigerated and frozen sorghum malt slurries in preservation of starter cultures for Obushera from Uganda

Industrial production of traditional fermented beverages is limited by lack of quality commercial starter cultures. Saccharomyces cerevisiae MNC21Y and Lactobacillus plantarum MNC21 can be used to ferment cereal beverages such as Obushera. These cultures are unavailable as commercial starters due to lack of appropriate propagating and distributing procedures. The purpose of this study was to evaluate the use of refrigerated and frozen sorghum slurries as carrier media for the starters. Starters were propagated in sorghum slurries (30°C for 24 h) and stored at 5°C and -18°C for 90 days. Viability of Saccharomyces cerevisiae and Lactobacillus plantarum was determined by cell counts after surface plating and pour plating, respectively. Fermentation ability was determined by inoculating sorghum slurries with starters and monitoring pH, acidity and flavor development. Viability was higher for starters stored at 5°C (S. cerevisiae: 6 log cfu.g-1 and Lb. plantarum: 7-9 log cfu.g-1 during 90 days) than those at -18°C (S. cerevisiae: 2 cfu.g-1 and Lb. plantarum: 4 log cfu.g-1 after 30 days). Refrigerated starters acidified Obushera (pH  4.5) faster (10-20 h) than frozen ones (18-24 h). Refrigerated or frozen S. cerevisiae + Lb. plantarum starters in sorghum malt slurries can remain viable for at least one or three months, respectively and produce Obushera with characteristic flavors.

Formulation, sensory attributes and nutrient content of a malted sorghum-based porridge: Potential for the management of moderate acute malnutrition among infants and young children

Introduction: Substituting corn in a fortified corn soy blend (CSB+) with enzyme-active sorghum malt has the potential to be a suitable alternative supplementary porridge in the management of infants and young children (IYC) with moderate acute malnutrition (MAM) in Uganda. Objective: To develop an acceptable malted sorghum-based supplementary porridge (MSBP) that meets the energy and protein specifications for the management of IYC with MAM, using locally-available ingredients. Methods: MSBP formulations included the use of malted sorghum flour and extruded soy and corn flour. The ratio of the soy to corn ingredients was 3:7 (F617/ F593), 1:1 (F892/ F940), and 4:1 for CSB+ , which is the standard care for the management of IYC with MAM in Uganda. The sorghum malt content for F617/ F892 and F593/ F940 was 25% and 30%, respectively. F617, F593, F892 and F940 met international specifications for a supplementary porridge. A comparison of the consumer acceptability scores and viscosity levels of these formulations was made, using analysis of variance. Results and Discussion: The scores for flavour, taste, mouth feel, sweetness and overall consumer acceptability differed among the formulations (p<0.05). F617 had a higher mean acceptability score than F593, F892 and F940 (p<0.05), as well as a higher energy and protein content than CSB+ (p<0.01). The energy density, protein density and viscosity of F617 were 1.6kcal/g, 4g/100 kcal and 2809 cP, respectively, at a flour rate of 25%. Conclusion: Sorghum malt is suitable for the development of an acceptable supplementary porridge (MSBP). It meets the international energy and protein specifications for the management of IYC with MAM, and the F617 formulation meets these specifications.