Center for Food Safety and Department of Food Science, University of Arkansas, Fayetteville, AR, USA 72704
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There continues to be interest in developing antimicrobial strategies to limit pathogens, including foodborne pathogens that are based on botanical products. Among these, berries have examined in the form of both extracts and juices for potential inhibitory properties against pathogens that are of public concern. Several candidates such as blueberries and cranberries appear to have potential along these lines. Of these, cranberry proanthocyanidins have been associated with specific anti-adhesion properties against uropathogenic
Since at least some pathogenic bacteria appear to be limited by cranberry juices and extracts, there is the potential that they could be used as interventions in nutritional diets and during food production.
It is estimated that millions of people are infected with a foodborne illness every year in the United States, leading to several billion in medical expenses and lost productivity. The most common sources of food poisoning include bacteria, with the primary ones being
The authors have referenced some of their own studies in this review. These referenced studies have been conducted in accordance with the Declaration of Helsinki (1964) and the protocols of these studies have been approved by the relevant ethics committees related to the institution in which they were performed. All human subjects, in these referenced studies, gave informed consent to participate in these studies. Animal care was in accordance with the institution guidelines.
Historically, the drive for more botanical sources of food additives comes from a multitude of sources including consumer nutritional inclination for foods based on organic and natural origins as well as increasing interest in plants as sources of medicinal compounds[24,25,26,27,28,29,30,31]. Numerous berry species have generally been touted as being rich in health, supporting phytochemicals such as antioxidants, anthocyanins and flavanoids. Berry species that have primarily been examined for such properties include blueberries, raspberries and strawberries[22,32,33,34,35,36,37]. However, issues remain in terms for retaining activity of these berry sources and their corresponding components during processing as well as during their passage through the gastrointestinal tract[32,36,38,39].
Along with the nutritional benefits, there is also an interest in assessing naturally occurring products such as these berry extracts for potential antimicrobial compounds that could be effectively and economically used in natural and organic systems[27,28,29,30,31,32,33,34,35,36,37,38,39,40]. There have been several studies on various berry fruit juices and extracts that demonstrate antimicrobial potential. Strawberry phenolic extracts have been shown to inhibit the growth of
Puupponen-Pimiä et al. examined the antimicrobial activity of pure phenolic compounds and extracts from common Finnish berries and found them to be effective inhibitors of Gram-negative bacteria but not Gram-positive bacteria. In a follow-up study, Puupponen-Pimiä et al. screened Nordic berries and their phenolic extracts and purified phenolic fractions for antimicrobial activity among a range of Gram-positive and Gram-negative human pathogenic bacteria. Among the berry species examined, cloudberry and raspberry appeared to be the most effective antimicrobials, with
While phenolics have been shown to be inhibitory to
Other fruits, such as blueberries, bilberries, muscadine grapes and chardonnay grapes, have been tested to a lesser extent as natural antimicrobials. The composition of blueberries has been fairly well characterized, but this has been more with regard to their human health benefits[35,54]. Less is known about their antimicrobial activities. Biswas et al. tested the antimicrobial properties of blueberry juice against the foodborne pathogens
Much of the interest in the impact of cranberries on reducing urinary tract infections focused on the mechanism(s) potentially associated with phytochemical components[57,61,62,66]. Early work on the anti-adhesion of
In general, the interference with specific pathogen attachment to biological surfaces has been suggested by Pappas and Schaich to be the primary mechanism by which cranberry constituents elicit anti-pathogen properties. Certainly, this appears to be the case with urinary tract infections, and Pappas and Schaich, given the wide variety of surfaces but only certain pathogens being inhibited, concluded that this anti-adherence property of cranberries is more likely linked to the specific organism rather than the surface. At least, some growth inhibition by cranberry extracts has also been reported for most of the major gastrointestinal pathogens including
How cranberries consumed either as a juice or in other edible forms behave against foodborne pathogens in the gastrointestinal tract is less certain. There are a number of factors that may come into play, which dictate relatively the effectiveness of cranberries and their various phytochemical components when in transit in the gastrointestinal tract. For example, natural flora based on bacterial fatty acid analyses of stool samples appeared to be unaffected in children consuming cranberry juice, suggesting that colonic bacterial balance was not influenced by the presence of cranberry juice constituents. There is indirect evidence for this as Pérez-Vicente et al. demonstrated that
Since at least some pathogenic bacteria appear to be limited by cranberry juices and extracts, there is the potential that they could be used as interventions in nutritional diets and during food production. In particular, the anti-adhesive properties could translate well into preventing pathogen colonization in the gut, and the bactericidal properties suggest that cranberry extracts could be applied as external antimicrobials for certain food products. For example, the high-molecular-weight inhibitors of the berries offer an attractive complement to the competitive exclusion mechanisms of the probiotic cultures, particularly since some of these bacterial species seem to not be harmed by cranberry constituents. One could envision a combination of probiotics and phenolic-rich berries as a dietary means to promote gastrointestinal tract health and select against pathogen establishment. However, this will require more research on the mechanism(s) to identify factors that may confound their effectiveness and in turn optimize their implementation.
Most of the current research is
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