![]() Carvacrol-containing essential oils are biostatic and/or biocidal against many bacteria, yeast and fungi in laboratory media and consequently have attracted considerable research attention as potential food preservatives ]. Generally recognized as a safe food additive, carvacrol is used as a flavouring agent in baked goods, sweets, beverages and chewing gum. Ĭarvacrol (2-methyl-5-(1-methylethyl)-phenol) is a major component of the essential oils of oregano and thyme. It has been suggested that many natural antimicrobial compounds from plant, animal and microbial sources might fulfil this need. Therefore, there is a need for new methods of fruit juice preservation that rely less heavily on severe heat treatment or the addition of synthetic preservatives. Warning labels are now required in the USA for all fruit juices unless a 5-log pathogen reduction treatment has been applied to the product. In the last 15 years, there have been several outbreaks of food poisoning associated with drinking un-pasteurised apple juice contaminated with enterohaemorrhagic Escherichia coli O157:H7 and several children have died in the USA. However, heat treatment causes vitamin losses and changes in flavour of the juices and some consumers regard heat-treated, shelf-stable products as low in quality. This ensures acceptable safety margins and extends the shelf-life of the juice. Any remaining bacterial spores are generally unable to germinate due to the acidic nature of the juices. The results showed that the natural antimicrobial compounds carvacrol and p-cymene could potentially be used to extend the shelf life and improve the safety margins in un-pasteurised chilled fruit juices.Ĭonventional fruit juice processing involves a heating step to inactivate the vegetative forms of pathogenic and spoilage microorganisms. coli O157:H7 thereby increasing the shelf-life and improving the safety of un-pasteurised apple juice, particularly when stored at chill temperatures. The phenolic compounds were biocidal against both spoilage yeasts and E. The effective concentrations of carvacrol could be reduced even further by combining it at 0.5 mM with cymene at 0.25 mM. ![]() coli O157:H7 to undetectable levels within 1–2 days at both storage temperatures. Treatment of the juice with 1.25 mM carvacrol or p- cymene reduced the numbers of E. When inoculated at a level of 4 log CFU/ml into un-pasteurised apple juice (pH 3.20 ± 0.06), Escherichia coli O157:H7 survived for up to 3 and 19 days at 25° and 4☌, respectively. ![]() The aim of this study was to evaluate the addition of very low concentrations (0.25–1.25 mM) of carvacrol and p- cymene both individually and in combination as a novel means of controlling Escherichia coli O157:H7 in un-pasteurised apple juice. The addition of natural antimicrobial substances such as the phenolic substances carvacrol and p- cymene (derived from the essential oils of herbs and spices) provides a potential new route to assure safety and extend the shelf-life of raw fruit juices. Therefore, alternative methods are being investigated to replace pasteurisation and improve the safety of minimally-processed juices. Whilst a well-established heat process (pasteurisation) will readily eliminate the pathogen, some consumers are demanding more fresh-like foods that have not been subjected to processing methods that are perceived as severe and may lead to loss of flavour and vitamins. Outbreaks of food poisoning associated with drinking un-pasteurised apple juice contaminated with enterohaemorrhagic Escherichia coli O157:H7 are a cause of serious illness and occasionally death.
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