No abstract

Kenaf seeds are a promising source of natural preservatives for food applications due to their potential as a substrate to generate peptides with high antibacterial activity. We sought to generate bioactive peptides with antibacterial activity from Kenaf seed proteins via lactofermentation. The ground seeds were defatted and protein extracted using acid precipitation. Kenaf seed protein was fermented with Lactobacillus casei for 72 h at 37 °C, and the antibacterial activity, MIC, and MBC were determined using a 96-well microtiter plate assay. The fermented protein was subjected to fractionation and peptide identification using reversedphase high pressure liquid chromatography and liquid chromatography-mass spectrometry, respectively. The fermented protein showed high antibacterial activity against Salmonella typhimurim, Escherichia coli, Psedomonas aerginosa, Staphylococcus aureus, Bacilus subtilis, and Streptococcus pyogenes. The MIC value was 4 mg/mL against all tested pathogens and the MBC value was 8 mg/mL against S. typhimurium, P. aureginosa, and E. coli and 4 mg/mL against B. subtilis, S. aureus, and S. pyogenes. Fraction 17 demonstrated the strongest antibacterial activity (98%-100%), and five peptides sequences were identified in this fraction. The findings of this study demonstrated high potential for kenaf seed protein fermented using Lactobacillus casei as a source of natural preservatives for a broad range of food applications.

Vibrio parahaemolyticus is a foodborne pathogen that is frequently isolated from a variety of seafood. To control this pathogenic Vibrio spp., the implementation of bacteriophages in aquaculture and food industries have shown a promising alternative to antibiotics. In this study, six bacteriophages isolated from the seafood samples demonstrated a narrow host range specificity that infecting only the V. parahaemolyticus strains. Morphological analysis revealed that bacteriophages Vp33, Vp22, Vp21, and Vp02 belong to the Podoviridae family, while bacteriophages Vp08 and Vp11 were categorized into the Siphoviridae family. All bacteriophages were composed of DNA genome and showed distinctive restriction fragment length polymorphism. The optimal MOI for bacteriophage propagation was determined to be 0.001 to 1. One-step growth curve revealed that the latent period ranged from 10 to 20 min, and the burst size of bacteriophage was approximately 17 to 51 PFU/cell. The influence of temperature and pH levels on the stability of bacteriophages showed that all bacteriophages were optimally stable over a wide range of temperatures and pH levels. In vitro lytic activity of all bacteriophages demonstrated to have a significant effect against V. parahaemolyticus. Besides, the application of a bacteriophage cocktail instead of a single bacteriophage suspension was observed to have a better efficiency to control the growth of V. parahaemolyticus. Results from this study provided a basic understanding of the physiological and biological properties of the isolated bacteriophages before it can be readily used as a biocontrol agent against the growth of V. parahaemolyticus.

The present work describes the effects of three different heat treatments to extend the shelf life and quality of sugarcane juice. Freshly extracted sugarcane juice samples were thermally treated by microwave heating; thermosonication, and conventional thermal processing to evaluate their effects on microbial loads, physicochemical properties, color changes, and quality parameters such as total phenolic content, antioxidant activity, and reducing sugars. Among all treatments, low power microwave was shown to be the best treatment by completely reducing the microbial loads to nondetection. The treatment was also able to preserve the total phenolic content (3.53), antioxidant activity (21.58), maintain the quality of physicochemical attributes, and minimize the overall color changes (ΔE* 4.76) as compared to other treatments. Overall, the present work provides an overview of alternative sugarcane juice treatments which could also be combined with hurdle technology that can further improve the quality and global market of the juice. Practical applications The present work seeks to improve the acceptance, quality, and shelf life of sugarcane juice by comparing conventional heating, microwave heating, and thermosonication. Currently, there are limited studies that emphasize to improve its quality as sugarcane juice is easily spoiled. The treatments proposed in this study are effective, cheap, more practical, and sustainable to be upscale for the larger production of sugar cane juice. This treatment could also be combined with hurdle technology or packaging technology that can further improve the quality, shelf life, and marketability of the juice.

The use of pure substrate represents a significant proportion of the cost of manufacturing a drug such as lovastatin. This study explores the production of lovastatin and (+)‐geodin by Aspergillus terreus ATCC 20542 using biodiesel‐derived crude glycerol (CG) as a feedstock. Shake flask experiments showed reduced lovastatin production and glycerol consumption in the presence of 10–50 g/L CG with respect to pure glycerol controls. At 50 g/L, lovastatin and (+)‐geodin production was significantly reduced by 82 and 73%, respectively. The lowest lovastatin inhibition was detected in 30 g/L of CG (48%), which was accompanied by a significant rise in (+)‐geodin production (338%). Further investigation was performed on three major impurities found in CG, namely methanol (MeOH), sodium chloride (NaCl), and fatty acids (oleic acid and palmitic acid (PA), soap). None was particularly inhibitory for lovastatin, except soap and PAs, which reduced its production by more than 50% at all concentrations tested. In contrast, (+)‐geodin was inhibited in the presence of MeOH and PA by up to 46 and 91%, respectively. These observations indicate that partial purification of CG would be potentially useful in improving production of lovastatin and (+)‐geodin by A. terreus.