HPLC method for the analysis of organic acids, sugars, and alcohol in extracts of fermenting cocoa beans

Microbiome Analysis of Sugarcane Juices and Biofilms from Louisiana Raw Sugar Factories

During postharvest processing of sugarcane for raw sugar, microbial activity results in sucrose loss and undesirable exopolysaccharide (EPS) production. Historically, culture-based approaches have focused on the bacterium Leuconostoc mesenteroides as the main contributor to both processes. However, recent studies have shown that diverse microbes are present in sugarcane factories and may also contribute to sugarcane juice deterioration. In the present study, high-throughput amplicon-based sequence profiling was applied to gain a more comprehensive view of the microbial community in Louisiana raw sugar factories. Microbial profiling of the bacterial and fungal microbiomes by 16S V4 and ITS1 sequences, respectively, identified 417 bacterial amplicon sequence variants (ASVs) and 793 fungal ASVs. While Leuconostoc was indeed the most abundant bacterial genus overall (40.9% of 16S sequences), multiple samples were dominated by other taxa such as Weissella and Lactobacillus, underscoring the microbial diversity present in sugarcane factories. Furthermore, flask cultures inoculated with the same samples demonstrated differences in the rate of sucrose consumption, as well as the production of exopolysaccharides and other organic acids, which may result from the observed differences in microbial composition. IMPORTANCE Amplicon-based sequencing was utilized to address long-ignored gaps in microbiological knowledge about the diversity of microbes present in processing streams at Louisiana sugarcane raw sugar factories. These results support an emerging model where diverse organisms contribute to sugarcane juice degradation, help to contextualize microbial contamination problems faced by raw sugar factories, and will guide future studies on biocontrol measures to mitigate sucrose losses and operational challenges due to exopolysaccharide production.

Biochemical and functional properties of wheat middlings bioprocessed by lactic acid bacteria

The present study aimed to investigate the bioprocessing of wheat middlings with different lactic acid bacteria (LAB) in order to improve biological activities of this by-product of wheat flour production. The concentration of lactic acid, reducing sugars, and total phenolics, as well as antioxidant, antibrowning, antibacterial and prebiotic activities of fermented samples were analyzed. All LAB strains were capable to growth on wheat middlings, and pH decreased in the medium associated with lactic acid production during cultivation. Samples inoculated with Lactobacillus plantarum DSM20174 presented the maximum growth, lactic acid concentration above 2 mg/ml, and pH values around 3.8. The amount or reducing sugars decreased after 24 hr growth, except for maltose. Bioprocessed wheat middlings exhibited antioxidant, antibrowning, antibacterial, and prebiotic properties, related with the increase of total phenolic content. Highest values for antioxidant activities were obtained for L. plantarum and Streptococcus thermophilus strains, reaching values around 400 and 640 μM Trolox equivalents (TE) ml^-1 for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) assays, respectively. Bioprocessing techniques using LAB can be an interesting approach to improve the availability of compounds with health-promoting properties from lignocellulosic waste material. PRACTICAL APPLICATIONS: The processing of secondary products from wheat milling can represent an important benefit to the industry. Wheat middlings bioprocessed with LAB showed improved biological activities and may represent an interesting ingredient to be incorporated in food and feed formulations.

Automated In Vitro Dermal Absorption (AIVDA): predicting skin permeation of atrazine with finite and infinite (swimming/bathing) exposure models

The Automated In Vitro Dermal Absorption (AIVDA) HPLC method developed in our laboratory for finite dose tests was developed further for infinite dose swimming/bathing exposure tests and for monitoring skin viability during the permeation assay. Skin absorption of the herbicide atrazine was tested under both finite and infinite dose conditions and the data compared to that obtained using the Bronaugh flow-through cell. Confirmation that skin viability was maintained throughout the AIVDA 24-hr infinite dose tests without phenol was obtained using a novel Radio-HPLC method that was developed to monitor glycolytic 14C-lactic acid formation in 14C-glucose spiked receiver solution. Advantages of the AIVDA method (e.g. rapid, sensitive, versatile, cost-effective analysis) together with its disadvantages (e.g. need for manual dexterity, lack of receiver albumin, compound retention time, limit of sampling interval) are discussed.