Microbial Synthesis of Lactic Acid from Cotton Stalk for Polylactic Acid Production

Cotton stalk, a waste product in agriculture, serves as a beneficial, low-cost material as a medium for microbial synthesis of lactic acid as desired for polylactic acid synthesis. Cotton stalk was used as a substrate for microbial lactic acid synthesis, and a novel strain of Lactococcus cremoris was reported to synthesize 51.4 g/L lactic acid using cellulose recovered from the cotton stalk. In total, 18 Lactobacillus isolates were isolated from kitchen waste, soil, sugarcane waste, and raw milk samples screened for maximum lactic acid production. It was found that one of the Lactococcus cremoris isolates was found to synthesize maximum lactic acid at a concentration of 51.4 g/L lactic acid in the hydrolysate prepared from cotton stalk. The upstream process parameters included 10% inoculum size, hydrolysate containing reducing sugars 74.23 g/L, temperature 37 °C, agitation 220 rpm, production age 24 h. Only the racemic (50:50) mixture of D-LA and L-LA (i.e., D/L-LA) is produced during the chemical synthesis of lactic acid, which is undesirable for the food, beverage, pharmaceutical, and biomedical industries because only the L-form is digestible and is not suitable for biopolymer, i.e., PLA-based industry where high optically purified lactic acid is required. Furthermore, polylactic acid was synthesized through direct polycondensation methods using various catalysts such as chitosan, YSZ, and Sb2O3. PLA is biocompatible and biodegradable in nature (its blends and biocomposites), supporting a low-carbon and circular bioeconomy.

The effects of camel milk powder on the stability and quality properties of processed cheese sauce

BACKGROUND

Camel milk contains all the essential nutrients as cow’s milk, and has potential beneficial nutritive properties. The drying process has a little effect on the surface composition of milk powders. The use of camel milk powder in the manufacture of processed cheese could produce a product with special functional properties.

METHODS

The effects of adding different concentrations of camel milk powder (CMP; ranging from 5 to 15%) as a new functional source to replace the cheese base in the manufacture of processed cheese sauces with highly acceptable quality and sensory properties were investigated.

RESULTS

All treatments varied significantly (p ≤ 0.05) in their properties depending on the percentage of CMP added and the storage period (6 ±0.5°C for 30 days). The pH, meltability, oil separation, viscosity and sensory properties of cheese sauce were measured during the storage period. Also, the chemical composition of the freshly prepared cheese sauces was examined. The moisture and total solids content decreased and increased significantly (p ≤ 0.05), in line with an increase of CMP in the cheese base formula, while the fat separation decreased with an increase in the percentage of camel milk powder added to the blends. The oil separation and meltability values increased (p ≤ 0.05) in all treatments, even in the control, throughout the storage period. Among treatments, the cheese sauce containing 15% CMP (T3) was characterized by higher viscosity values during the examined time of shearing and presented higher upward shifting of the flow curve, as compared with the other treatments, either fresh or during storage. All cheese treatments were more accepted by the panelists and rated above average, particularly with an increase in the ratio of CMP added of 10%.

CONCLUSIONS

The addition of CMP improved (p ≤ 0.05) the quality attributes of cheese sauces and could be considered as a new different source to substitute cheeses used in base blends of processed cheese.

Coconut Bio-yoghurt Phytochemical-chemical and Antimicrobial-microbial Activities

BACKGROUND AND OBJECTIVE

Coconut flour is known to be highly nutritious flour and contains high dietary fiber. The aim of this study was to make "bio-yoghurt beverage grafted with coconut flour and containing probiotic bacteria which is recommended as a functional milk product.

MATERIALS AND METHODS

Chemical, phytochemical studies and antimicrobial activity have been performed on coconut flour which was used to make the beverage. Bio-yoghurt beverages made with different ratios of coconut flour (0, 2, 4 and 6%) were chemical, microbiological and sensory tested when fresh and during storage for 15 days of cold storage.

RESULTS

Chemical composition of coconut flour showed reasonable contents of moisture, ash, fat, fatty acids, protein, crude fiber, total solids, total phenols and antioxidants. Coconut flour showed antibacterial activity against some foodborne pathogenic bacteria. The addition of coconut flour to make bio-yoghurt beverages increased its contents of total solids, protein, ash, fiber, acidity, antioxidant activity, total phenols, improved yoghurt sensory and rheological properties especially when probiotic bacteria were used. The results did not reveal any significant differences (p>0.05), between the bacterial counts of yoghurt starter culture, Lactobacillus rhamnosus, Lactobacillus casei in yoghurt control (without coconut) and bio-yoghurt treatments (with coconut), during cold storage. Moulds and yeasts were not detected in all bio-yoghurt treatments; meanwhile they appeared in yoghurt control after 15 days indicating coconut antifungal activity and subsequently a period of time to save more for this drink. All bio-yoghurt beverages with different ratios of coconut flour were sensory accepted and showed more favorable properties, particularly for the viscosity.

CONCLUSION

A new functional dairy product of bio-yoghurt beverage contain coconut flour high fiber content was prepared with probiotic bacteria and showed good chemical, microbiological and sensory/rheological properties.