Journal Articles

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    Antibacterial efficacy and possible mechanism of action of 2-hydroxyisocaproic acid (HICA)
    (PLOS, 2022-04-01) Pahalagedara ASNW; Flint S; Palmer J; Brightwell G; Gupta TB; Nevárez-Moorillón GV
    The exploitation of natural antimicrobial compounds that can be used in food preservation has been fast tracked by the development of antimicrobial resistance to existing antimicrobials and the increasing consumer demand for natural food preservatives. 2-hydroxyisocaproic acid (HICA) is a natural compound produced through the leucine degradation pathway and is produced in humans and by certain microorganisms such as lactic acid bacteria and Clostridium species. The present study investigated the antibacterial efficacy of HICA against some important bacteria associated with food quality and safety and provided some insights into its possible antimicrobial mechanisms against bacteria. The results revealed that HICA was effective in inhibiting the growth of tested Gram-positive and Gram-negative bacteria including a multi-drug resistant P. aeruginosa strain in this study. The underlying mechanism was investigated by measuring the cell membrane integrity, membrane permeability, membrane depolarisation, and morphological and ultrastructural changes after HICA treatment in bacterial cells. The evidence supports that HICA exerts its activity via penetration of the bacterial cell membranes, thereby causing depolarisation, rupture of membranes, subsequent leakage of cellular contents and cell death. The current study suggests that HICA has potential to be used as an antibacterial agent against food spoilage and food-borne pathogenic bacteria, targeting the bacterial cell envelope.
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    Monascus spp. and citrinin: Identification, selection of Monascus spp. isolates, occurrence, detection and reduction of citrinin during the fermentation of red fermented rice
    (Elsevier BV, 2022-10-16) Farawahida AH; Palmer J; Flint S
    Red fermented rice (RFR) is rice fermented using Monascus spp. This product contains monacolin K, providing health benefits including mitigation of diarrhoea and improving blood circulation. RFR can produce pigments that can act as natural colour and flavouring agents. However, Monascus spp. (a fungal starter to ferment RFR) can also produce the mycotoxin, citrinin (CIT) which is believed to have adverse effects on human health. CIT in RFR has been reported worldwide by using different methods of detection. This review focuses on the production of RFR by solid-state fermentation (SSF) and submerged fermentation (SmF), the occurrence of CIT in RFR, CIT quantification, the factors affecting the growth of Monascus spp., pigments and CIT production in RFR, and possible methods to reduce CIT in RFR. This review will help the food industries, researchers, and consumers understand the risk of consuming RFR, and the possibility of controlling CIT in RFR.