Phenolic compounds and related enzymes as determinants of sorghum for food use

Phenolic compounds and related enzymes such as phenol biosynthesizing enzymes (phenylalanine ammonia lyase) and phenol catabolizing enzymes (polyphenol oxidase and peroxidase) are determinants for sorghum utilization as human food because they influence product properties during and after sorghum processing. Phenolic compounds are quality-grade markers for the preparation of several foods because of enzyme inhibitory activities, color, or antioxidant activities. Large inter-varietal differences in contents of phenolic compounds and their antioxidant activities among sorghum varieties exist. Moreover, some red sorghum varieties have higher antioxidant activities than the most important sources of natural antioxidants. Oxidation products of peroxidase and polyphenol oxidase (benzoquinones and polymeric compounds) affect food quality. This paper reviews the current advances in phenolic compounds and phenolic enzymes in sorghum as human food, with emphasis on nutritional and health aspects. The suitability of sorghum varieties for food and beverages is discussed

Antioxidant and antibacterial activities of polyphenols from ethnomedicinal plants of Burkina Faso

Polyphenols from four medicinal plants of Burkina Faso, Combretum micranthum, Khaya senegalensis, Pterocarpus erinaceus and Sida acuta, were screened for their antioxidant and antimicrobial activities against pathogenic bacteria. The medicinal plants displayed different polyphenols contents and antioxidant activities. The bark of P. erinaceus had the highest antioxidant activity. Some microorganisms were susceptible to polyphenol extracts with minimal bactericidal concentration values between 20 and 2000 mg/ml while other microorganisms appeared to be resistant to the extracts. Microbicide and microbiostatic activities of the extracts were dependent on the type of strains. Results suggest that these plants are not only interesting sources for antimicrobial activities but also potential sources of phenolic antioxidants

Endogenous phenolics and starch modifying enzymes as determinants of sorghum for food use in Burkina Faso

The objective of this thesis is to screen for biochemical determinants in sorghum varieties cultivated in Burkina Faso to identify the best sorghum varieties to be used as source of bioactive components or for specific local foods, e.g. "tô", thin porridges for infants, granulated foods "couscous", and local beers "dolo". The results revealed that sorghum varieties have different contents of starch, amylose, amylopectin and that germination decreased more the content of amylose than amylopectin. While on averagea‑amylase activity increased in all varieties by 2-20fold,b‑amylase activity did not uniformly increase after germination and even decreased in some varieties. The majority (82%) of sorghum varieties cultivated inBurkina Fasoare low proanthocyanidins (condensed tannins) containing sorghums. Some varieties had relatively high content(> 0.4%, w/w),of phenolic compounds such as 3-deoxyanthocyanidins and flavan-4-ols, which are of particular interest for food, colorant and pharmaceutical industries. Independent of grain germination, all sorghum varieties are among the most prominent natural sources of antioxidants due essentially to their phenolic contents. Sorghum varieties are highly polymorph in their expression of phenolic biosynthesizing enzymes, e.g. phenylalanine ammonia lyase, and phenolic modifying enzymes, e.g. peroxidases and polyphenol oxidases. Several peroxidase isoenzymes are expressed both before and after germination, and display a high activity in vitro . These enzymes are the main potential oxidases involved in the oxidation of endogenous phenolic compounds in sorghum grain. The major sorghum grain peroxidase isoenzyme representing more than 80% of total peroxidase activity was characterized at the molecular level. The enzyme, localized in chromosome 1 of sorghum, is a monomeric glycoprotein containing a non-covalently bound type-b heme. The catalytic properties and primary structure of the enzyme are similar to cereal peroxidases, in particular to barley peroxidase 1. Agronomic characteristics of grains (presence of absence of pigmented testa layer and color of the glumes) and plants (red or tan) could be linked to sorghum grain contents in phenolics and starch modifying enzymes. On average, varieties resistant to stresses have greater content and diversity in phenolic compounds and higher oxidative enzyme activities than stress susceptible varieties. The screened biochemical parameters could be linked to the preferences of varieties for specific local foods. For instance, among varieties used for "tô", "dolo", couscous and thin porridge preparation, the "dolo" varieties had the highest average content and diversity in phenolics as well as the highest antioxidant activities. Varieties good for infant porridges preparation have low amylose content and higha-amylase activity after germination

Animal nutrition

Discusses the effects of the interaction among genotype, animal health & nutrition on livestock productivity within a particular environment, w. spec. ref. to results of work undertaken by ILCA on the nutrition component of the system, using availability & composition of forage, and composition & amount of food eaten to study grazing behaviour, feed intake and performance of animals

Indigenous West African plants as novel sources of polysaccharide degrading enzymes: application in the reduction of the viscosity of cereal porridges

Ethnobotanical and biochemical surveys revealed that some local plants from West Africa are novel sources of polysaccharide degrading enzymes such as amylases and glucanases. The study shows that these enzymes could be used for various biotechnological applications. In a crude extract of Curculigo pilosa, ß-amylase was the main starch hydrolyzing enzyme. Contrary to other plant amylases, the ß-amylase from C. pilosa is able to degrade raw starches from wheat, corn, potato and rice. In the bulbs of Gladiolus klattianus, activities of a-amylase and ß-amylase were found. Analysis of the enzyme action pattern showed that it released only maltose units from starch. Activities of aamylase, ß-amylase, exo-(1®3, 1®4)-ß-D-glucanase and endo-(1®3)-ß-D-glucanase were detected in the leaves of Boscia senegalensis. The combined action of a saccharogenic enzyme (ß-amylase) and a dextrinizing enzyme (a-amylase) in B. senegalensis was useful to decrease the viscosity of cereal porridges and to increase their reducing sugar contents. The effective technological utilization of these higher plants as sources of carbohydrate degrading enzymes is discussed

Biochemical characterization of the major sorghum grain peroxidase

The major cationic peroxidase in sorghum grain (SPC4) , which is ubiquitously present in all sorghum varieties was purified to apparent homogeneity, and found to be a highly basic protein (pI 11). MS analysis showed that SPC4 consists of two glycoforms with molecular masses of 34227 and 35629 Da and it contains a type-b heme. Chemical deglycosylation allowed to estimate sugar contents of 3.0% and 6.7% (w/w) in glycoform I and II, respectively, and a mass of the apoprotein of 33 246 Da. High performance anion exchange chromatography allowed to determine the carbohydrate constituents of the polysaccharide chains. The N-terminal sequence of SPC4 is not blocked by pyroglutamate. MS analysis showed that six peptides, including the N-terminal sequence of SPC4 matched with the predicted tryptic peptides of gene indice TC102191 of sorghum chromosome 1, indicating that TC102191 codes for the N-terminal part of the sequence of SPC4, including a signal peptide of 31 amino acids. The N-terminal fragment of SPC4 (213 amino acids) has a high sequence identity with barley BP1 (85%), rice Prx23 (90%), wheat WSP1 (82%) and maize peroxidase (58%), indicative for a common ancestor. SPC4 is activated by calcium ions. Ca2+ binding increased the protein conformational stability by raising the melting temperature (Tm) from 67 to 82 °C. SPC4 catalyzed the oxidation of a wide range of aromatic substrates, being catalytically more efficient with hydroxycinnamates than with tyrosine derivatives. In spite of the conserved active sites, SPC4 differs from BP1 in being active with aromatic compounds above pH

Antioxidant and antibacterial activities of polyphenols from ethnomedicinal plants of Burkina Faso

Polyphenols from four medicinal plants of Burkina Faso, Combretum micranthum, Khaya senegalensis, Pterocarpus erinaceus and Sida acuta, were screened for their antioxidant and antimicrobial activities against pathogenic bacteria. The medicinal plants displayed different polyphenols contents and antioxidant activities. The bark of P. erinaceus had the highest antioxidant activity. Some microorganisms were susceptible to polyphenol extracts with minimal bactericidal concentration values between 20 and 2000 mg/ml while other microorganisms appeared to be resistant to the extracts. Microbicide and microbiostatic activities of the extracts were dependent on the type of strains. Results suggest that these plants are not only interesting sources for antimicrobial activities but also potential sources of phenolic antioxidants

Photoacoustic approach in direct determination of the total phenolic content in Red Sorghum Flours

Photoacoustic (PA) spectroscopy in the ultraviolet and visible was demonstrated to be a suitable tool for direct determination of total phenolic content in red sorghum flours. The PA spectra obtained feature two characteristic peaks: the first centered at 285 nm is due to the aromatic amino acids, while the second one at 335 nm is associated with the total phenolic content. The outcome of the PA study was compared with the results obtained by a conventional, tedious Folin-Ciocalteau chemical method. Statistical analysis indicates no significant difference between the two methods used in this study