Lactic acid, an anaerobic product of glycolysis, can be theoretically produced by synthetic route; however, it is commercially produced by homo-fermentative batch mode of operations. Factors affecting its production and strategies improving it are considered while devising an optimized protocol. Although a hetero-fermentative mode of production exists, it is rarely used for commercial production. Attempts to use Rhizopus sp. for lactic acid production through either hetero-fermentative or thermophilic conditions were not economical. Since almost 70% of the cost of its production is accounted by raw materials, R & D efforts are still focused to find economically attractive agri-products to serve as sources of carbon and complex nitrogen inputs to meet fastidious nutrient needs for microbial growth and lactic acid production. Therefore, need exists for using multi-pronged strategies for higher productivity. Its present production and consumption scenario is examined. Its optically active isomers and chemical structure permit its use for the production of several industrially important chemicals, health products (probiotics), food preservatives, and bio-plastics. In addition, its salts and esters appear to have a variety of applications.
Bonding agents are auxiliary but critical additives in composite propellants. The bonding agent ameliorates the processing and mechanical performance of propellant through interfacial interaction between particulate fillers and binder matrix. Several bonding agents have been developed over the years to treat the dewetting problem of the composite solid propellant. In this review, we describe the different types of bonding agents, their bonding mechanism and development in the composite propellants. An individual bonding agent is discussed critically in terms of its strengths and weaknesses. The review provides an understanding of the developments of the bonding agent in the field of composite solid propellants.
Lactic acid production has been carried out using (a) Lactobacillus delbruckii, (b) optimal production medium comprised of 10% carbon source derived from sweet sorghum (SS) (Sorghum bicolor)/golden syrup (GS; molasses after glucose crystallization)/date palm (DP) juice (Phoenix dactylifera L.), 1% yeast extract, 0.6% sodium acetate, 0.5% KH2PO4, and 0.5% MgSO4 · 7H2O, (c) in batch mode, (d) at 45 ± 1°C, 150 rpm, anaerobic condition, and pH 5.5 ± 0.1, and (e) sterilized CaCO3 powder at regular intervals for neutralization to promote optimal utilization of sugar. The lactic acid (LA) productivity was higher from the use of GS and less from SS as well as DP juice. Decolorization of carbon sources prior to use in fermentation gave LA, meeting food grade specifications.
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