A study on effect of fermentation conditions on citric acid production from cassava peels

Butyric and Citric Acids and Their Salts in Poultry Nutrition: Effects on Gut Health and Intestinal Microbiota

Intestinal dysfunction of farm animals, such as intestinal inflammation and altered gut microbiota, is the critical problem affecting animal welfare, performance and farm profitability. China has prohibited the use of antibiotics to improve feed efficiency and growth performance for farm animals, including poultry, in 2020. With the advantages of maintaining gut homeostasis, enhancing digestion, and absorption and modulating gut microbiota, organic acids are regarded as promising antibiotic alternatives. Butyric and citric acids as presentative organic acids positively impact growth performance, welfare, and intestinal health of livestock mainly by reducing pathogenic bacteria and maintaining the gastrointestinal tract (GIT) pH. This review summarizes the discovery of butyric acid (BA), citric acid (CA) and their salt forms, molecular structure and properties, metabolism, biological functions and their applications in poultry nutrition. The research findings about BA, CA and their salts on rats, pigs and humans are also briefly reviewed. Therefore, this review will fill the knowledge gaps of the scientific community and may be of great interest for poultry nutritionists, researchers and feed manufacturers about these two weak organic acids and their effects on intestinal health and gut microbiota community, with the hope of providing safe, healthy and nutrient-rich poultry products to consumers.

Biotechnological valorization of cashew apple juice for the production of citric acid by a local strain of Aspergillus niger LCFS 5

Background

This work investigates the production of citric acid from cashew apple juice, an abundant waste in the processing of cashew, using a local strain of Aspergillus niger and the application of the citric acid as a coagulant for the production of soy cheese. Fungal isolates were obtained from a cashew plantation in Ogbomoso, Nigeria, using potato dextrose agar. Further screening was undertaken to determine the qualitative strength of acid production by the fungi on Czapek-Dox agar supplemented with bromocresol green, with the development of yellow zone taken as an indication of citric acid production. Thereafter, the best producing strain was cultivated in a cashew apple juice medium.

Results

Out of 150 fungal isolates generated from the cashew plantation, 92 (61.3%), 44 (29.3%) and 14 (9.3%) were obtained from cashew fruits, soil and cashew tree surfaces, respectively. Different strains of fungi isolated include Aspergillus niger, A. flavus, A. foetidus, A. heteromorphus, A. nidulans and A. viridinutans. The isolates produced yellow zonation of 0.4–5.5 cm on modified Czapek-Dox agar; the highest was observed for a strain of A. niger LCFS 5, which was identified using molecular tools. In the formulated cashew apple juice medium, the citric acid yield of LCFS 5 ranged 16.0–92.8 g/l with the peak obtained on the 10th day of fermentation. The citric acid produced was recovered using the double precipitation method with Ca(OH)₂ and H₂SO₄ having ≈ 70% purity of citric acid on HPLC. The citric acid acted as a coagulant to produce soy cheese with 66.67% acceptability by panelists.

Conclusion

This work has extended the frontiers of valorization of cashew waste by a strain of A. niger to produce citric acid in high yield, with potential application in food industries.