Optimization of Lactic Acid Production from Pineapple By-Products and an Inexpensive Nitrogen Source Using Lactiplantibacillus plantarum strain 4O8.

Lactic acid (LA) is used in food, cosmetic, chemical, and pharmaceutical industries and has recently attracted much attention in the production of biodegradable polymers. The expensive substances including carbon and nitrogen sources involved in its fermentative synthesis and the increasing market demand of LA have prompted scientists to look for inexpensive raw materials from which it can be produced. This research was aimed at determining the optimum conditions of lactic acid (LA) production from pineapple by-products and an inexpensive nitrogen source using Lactiplantibacillus plantarum strain 4O8. After collection and preparation of the carbon source (pineapple by-products) and nitrogen sources (by-products from fish, chicken, and beer brewing industries), they were used for the formulation of 4 different media in terms of nitrogen sources. Then, the proximate compositions of promising nitrogen sources were determined. This was followed by the screening of factors (temperature, carbon source, nitrogen source, MgSO4, MnSO4, FeSO4, KH2PO4, and KHPO4) influencing the production of LA using the definitive plan. Lastly, the optimization process was done using the central composite design. The highest LA productions (14.64 ± 0.05 g/l and 13.4 ± 0.02 g/l) were obtained in production medium supplemented with chicken and fish by-products, respectively, making them the most promising sources of nitrogen. The proximate analysis of these nitrogen sources revealed that their protein contents were 83.00 ± 1.41% DM and 74.00 ± 1.41% DM for chicken by-products and fish by-products, respectively. Concerning the screening of factors, temperature, nitrogen source, and carbon source were the factors that showed a major impact on LA production in the production medium containing chicken by-products as nitrogen source. A pineapple by-product concentration of 141.75 g/l, a nitrogen source volume of 108.99 ml/l, and a temperature of 30.89°C were recorded as the optimum conditions for LA production. The optimization led to a 2.73-fold increase in LA production when compared with the production medium without nitrogen source. According to these results, chicken by-products are a promising and an inexpensive nitrogen source that can be an alternative to yeast extract in lactic acid production.

Optimum biscuit from Musa sapientum L. and Vigna unguiculata L. composite flour: effect on pancreatic histology, biochemical and hematological parameters of diabetic rats.

This study investigated the effect of consumption of an optimum biscuit from composite flour of Musa sapientum L. ('banana cochon') and Vigna unguiculata L. (cowpea) on the pancreatic histology, biochemical and hematological parameters of streptozotocin-induced diabetic Wistar rats. The optimum biscuit was evaluated for its chemical properties and glycaemic index. The weekly fasting blood glucose level, food intake and weight of the rats were recorded. The effect of 28 days' consumption of different percentages of optimum biscuit with/without Metformin was also evaluated on the pancreatic histology, biochemical and hematological parameters of rats. Results showed that, the optimum biscuit is rich in minerals (potassium, magnesium and calcium), dietary fibre (9.4%) and is a low glycaemic index product (50.91%). Also, the optimum biscuit significantly lowered/maintained the blood glucose level of diabetic rats even though the weekly weights of the rats were reduced while food intake increased. Nonetheless, the hematological parameters of the treated diabetic rats were significantly (P < 0.05) improved when compared to the untreated diabetic rats groups. With the exception of total serum protein, other biochemical parameters such as serum creatinine, urea, alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase and bilirubin in the treated diabetic groups were significantly (P < 0.05) reduced or closer to those of non-diabetic rats. The serum cholesterol, triglyceride, low-density lipoprotein levels were significantly (p < 0.05) reduced while the HDL level significantly increased in treated diabetic groups. Histological examination of the pancreas showed that treatment of diabetic groups with optimum biscuit was able to slow down the destruction (protection) of beta-cells. Thus, optimum biscuit could be used to improve the health status during the management and prevention of complications in diabetic patients.

Lactic acid production ability of Lactobacillus sp. from four tropical fruits using their by-products as carbon source.

The present work was aimed at studying the technological properties of lactobacilli isolated from four tropical fruits (banana, papaya, pineapple, and orange) sold in Dschang (a city of the Menoua Division, West-Cameroon), as well as their ability to produce lactic acid (LA) from by-products of these fruits. After isolation and preliminary identification, homofermentative isolates were investigated for acidifying, amylolytic, cellulolytic activities as well as exopolysaccharides production. The chemical composition of the by-products was determined prior to fermentation assays and the most promising isolates were identified by 16S rRNA gene sequencing. From the 54 homofermentative lactobacilli obtained, 9 isolates were pre-selected based on their higher acidifying activity in MRS-Glucose medium. They all showed amylolytic activity, with the most important activity (54.26 ± 0.10 µg of reducing sugar/ml/min) recorded by isolate O31. Relatively to their cellulolytic activity, isolate 1B9 showed the best activity, displaying a production rate of 7.98 ± 0.40 µg glucose/ml/min, while none of them produced exopolysaccharides. The proximate analysis showed that the fruit-derived by-products contained proteins (0.40 ± 0.06% DM to 1.54 ± 0.06% DM), carbohydrates (61.75 ± 0.75% DM to 71.94 ± 2.02% DM) that are main nutrient needs for bacterial growth. Banana-derived and pineapple-derived by-products showed the highest LA production rates with values, 26.37 ± 0.05 g/l (isolate 3A5) and 26.29 ± 0.38 g/l (isolate 1B9) respectively after 16 h of fermentation. Based on the principal component analysis, isolates O31, 1B9, 3A5, 3A9 and 4O8 were selected as the most promising isolates and were identified as Lactobacillus plantarum strains. According to the obtained results, lactobacilli from tropical fruits displayed properties of commerical interest and can be promising candidates in the valorisation of by-products from tropical fruits through LA production.

Effect of traditional and oven roasting on the physicochemical properties of fermented cocoa beans.

The objective of this study was to determine the effect of oven and traditional roasting on the polyphenol content, antioxidant activity, lipid quality, proximate composition and mineral content of fermented cocoa beans. Results showed that traditional roasting significantly decrease (p < 0.05) the polyphenol content and antioxidant activity of cocoa beans. The analysis of oil showed that oven and traditional roasting significantly increase (p < 0.05) the peroxide and thiobarbituric acid values of cocoa butter and that traditional roasting samples were the most deteriorated. Oven and traditional roasting for 10 min reduce the iodine value of the oil, but increase its acidity. The proximate and mineral composition of cocoa beans was also seriously affected during cooking. Drying and oven roasting for 5 and 10 min; and drying and traditional roasting for 5 min appear to be the best processing methods of cocoa beans for production of cocoa based foods like chocolate.

Effect of Boiling and roasting on lipid quality, proximate composition, and mineral content of walnut seeds (Tetracarpidium conophorum) produced and commercialized in Kumba, South-West Region Cameroon.

The effect of boiling and roasting on the lipid quality, proximate composition, and mineral content of African walnut seeds (Tetracarpidium conophorum) was assessed. Results indicated that the quality of walnut oil significantly (p < .05) reduces with the treatments. Oils extracted from DBWN 60 min (Dried and boiled walnuts 60 min) and FBWN 60 min (Boiled fresh walnuts 60 min) were the most altered. The proximate composition and mineral content of walnut seeds was also significantly affected (p < .05) by the treatments. This study reveals that, thermal processing has significant effects on the nutrients and quality of lipids of walnut oil. DTRWN 60 min (Dried and traditionally roasted walnuts 60 min), DORWN 60 min (Dried and oven roasted walnuts 60 min), and TRFWN 30 min (traditionally roasted fresh nuts 30 min) are the best methods for cooking walnut because they preserve the quality of its lipids and some of the nutrients.