Consumption Of Fermented Foods Research Articles

Botulism among Alaska natives in the Bristol Bay area of southwest Alaska: a survey of knowledge, attitudes, and practices related to fermented foods known to cause botulism

Objectives. Botulism cases due to traditional Alaska Native fermented foods occur periodically in Southwest Alaska. In this population, we conducted a survey on knowledge, attitudes, and practices related to botulism and fermented foods. Methods. We interviewed 140 adults randomly chosen from nine villages. Data collected included fermented food consumption frequency; knowledge about the cause and symptoms of botulism; and fermented food preparation methods. Results. Most respondents (81%) had eaten Alaska Native fermented foods at least once. Over 70% identified botulism as a foodborne illness, and over 87% believed eating certain Native fermented foods could cause botulism. One-third of fermented food preparers used plastic containers for fermentation. To prevent botulism, 45% would consider boiling fermented foods, and 65% would not eat foods fermented in plastic or glass containers Conclusions. Despite high awareness of botulism in this population, one-third of fermented food preparers use plastic containers, a practice which may increase the risk of botulism. Misconceptions and acceptable prevention messages about botulism, such as using traditional nonplastic fermentation methods, were identified and included in an educational video.

Anti-allergy properties of fermented foods: an important immunoregulatory mechanism of lactic acid bacteria?

Clinical reports have suggested that dietary consumption of fermented foods, such as yogurt, can alleviate some of the symptoms of atopy and might also reduce the development of allergies, possibly via a mechanism of immune regulation. Controlled studies have indicated that consumption of fermented milk cultures containing lactic acid bacteria (LAB) can enhance production of Type I and Type II interferons at the systemic level. In animal models, LAB have been shown to promote interferon expression, and to reduce allergen-stimulated production of IL-4 and IL-5 in some cases. Recent results have shown that LAB are potent inducers of pro-interferon monokines (IL-12 and IL-18), and that cytokine secretion is stimulated by the interaction of Gram-positive cell wall components with surface receptors of mononuclear phagocytes, via NF-κB and STAT signalling pathways. However, it is clear that the extent and quality of LAB-induced immunoregulation is strain-dependent. This review discusses the clinical and laboratory evidence for anti-allergy properties of fermented foods, and proposes a model for the mechanism by which some well-defined strains of immunoregulatory LAB might down-regulate a Th2 allergic phenotype.

HPLC based method for the measurement of the reduction of aflatoxin B1 by bacterial cultures isolated from different African foods

The consumption of fermented foods contaminated with aflatoxin B1 is linked to aflatoxicosis. Aflatoxicosis is a serious problem in developing countries with environmental conditions appropriate for the biosynthesis of AFB1 byAspergillus flavus andAspergillus parasiticus. In Africa, especially in Ghana and Nigeria, there is a very high risk of liver cancer which is caused by the consumption of AFB1-intoxicated, traditionally fermented maize and sorghum products. It is suggested that one way to diminish this health risk might be the reduction of the AFB1 concentration in foods by bacteria. Especially bacteria used for food fermentation processes are of great importance, with a special emphasis on lactic acid bacteria which are involved in traditionally fermented African foods based on maize and sorghum.Most publications dealing with aflatoxin degradation by microorganisms describe a phosphate buffer test system for the performance of degradation experiments. In contrast to that, a test system based on physiological active bacterial and yeast cells has been developed, to assess food fermentation organisms for their ability to reduce the AFB1 concentration in vitro. The aflatoxin B1 concentration in test samples was quatitatively determined by HPLC.The assessment of lactic acid bacteria originating from different German and other European culture collections only showed a very slight reduction of the AFB1 concentration from 3% to 12%. Screening experiments in which other bacterial genera and lactic acid bacteria, isolated from different African foods have been assessed, in most cases showed the same results. However, some bacterial strains, e.g. strains of the genusBacillus derived from European culture collections and strains of the genusLactobacillus isolated from African foods, caused a release of AFB1 which was chemically bound before to components of the test medium and which therefore could not be extracted with chloroform.A process quite similar to that may happen during food fermentations. Different experiments showed that e.g. cellulose can bind AFB1 very effectively. Cellulose and different other food components are well known to absorb AFB1. During fermentation the cellulose and other AFB1-absorbing components may be degraded and the AFB1 will be released again.The only bacterial strain known as yet which is able to reduce the AFB1 concentration in vitro and in different food comodities isNocardia corynebacteroides (formerFlavobacterium aurantiacum). Nevertheless the mechanism of this AFB1 reduction is actually not well understood, it still has to be investigated. In the meantime several other bacterial strains, presumably from the taxonomic group of theActinomycetes could be proved to be effective reducers of the AFB1 concentration in our in vitro test system. Because as yet no food relevant microorganism could be found, which is able to degrade AFB1, these new strains in general offer the possibility for a genetic modification of food relevant microorganisms. This seems to be the way to come to starter cultures which are able to degrade AFB1 during food fermentations.

Inhibition of enterotoxin production by, and growth of enteropathogens in a lactic acid-fermenting cereal gruel

Growth and enterotoxin production of three strains of Campylobacter jejuni or Escherichia coli known to produce heat labile enterotoxins were evaluated when added into a lactic acid-fermenting cereal gruel, togwa. A single strain of each of the enteropathogens was simultaneously inoculated with a lactic acid starter culture (sc) to reach a level of about 107 c.f.u./ml and was left to ferment for 48h. Gruels without sc (control gruel), pure cholera toxin in fermenting or control gruel and the test bacteria inoculated into nutrient broth were used as positive toxin controls; gruel without inoculated test bacteria was the toxin-negative control. Viable colonies were counted by spread plating 0.1ml of gruel subsamples collected at intervals during the fermentation period onto different selective media and the heat labile enterotoxin production was evaluated using an assay on Chinese hamster ovary (CHO) cells. In the fermenting gruels, no viable cells of the C. jejuni and E. coli strains were detected after 8 and 24h incubation, respectively, but inocula increased in number or remained at the initial level in the control gruel and in the nutrient broth. After 24h incubation, all supernatants of control gruels with inoculated bacteria showed enterotoxicity to the CHO cells (indicated by elongation of 20–50% of the cells). No toxin activity was observed in the fermenting gruels with or without added bacteria or in control gruel alone. Pure cholera toxin added to control gruel caused the enterotoxigenic effect in 70–100% of the CHO cells, but no activity was detected when it was added to the fermenting gruel. The CHO cells were affected instead by a low pH level but were not elongated. Adjusting the pH of fermented gruels to approximately neutral levels restored the toxin effect when cholera toxin was added but not in the presence of added test bacteria. We conclude that lactic acid fermented cereal gruels with pH ≤4 have a high potential to inhibit the growth of enteropathogenic bacteria of the genera C. jejuni and E. coli and to inhibit production of heat labile enterotoxins. Regular consumption of fermented cereal weaning foods will therefore reduce transmission of enterotoxin-producing bacteria, and ingestion of enterotoxins.

Assessment of fermentation as a household technology for improving food safety: a joint FAO/WHO workshop

Food safety and nutritional aspects of lactic acid fermentation processes for the purpose of complementary food preparation at household scale in tropical countries were assessed during an FAO/WHO workshop held in Pretoria, South Africa in December 1995. Lactic acid fermentation was evaluated in particular, taking into consideration that microbial fermentation is only a part of the food preparation processes involving other operations such as soaking, cooking and the use of germinated cereals. The latter are of special interest as they enable the preparation of semiliquid porridges of high-nutrient density. The present state of knowledge concerning the antimicrobial effects imparted by the acidity in lactic-fermented foods was reviewed, as well as the nutritional benefits of fermentation and use of germinated cereals. Areas requiring further research were identified and prioritized. It was concluded that high priority should be given to research on: the effect of lactic acid fermentation on viruses, parasites, some bacteria and mycotoxins; risk assessment using the HACCP approach, health education of food handlers and consumer perception of fermented foods; characterization and optimization of fermentation processes and development of appropriate starters; and some physiological and nutritional effects of consumption of fermented foods.

A Cell Culture Model to Identify Biologically Active Peptides Generated by Bacterial Hydrolysis of Casein

Consumption of fermented dairy foods has been linked to reduced incidence of colon cancer in population groups. Recently, biologically active compounds have been isolated from these products. Bacterial proteinases, produced by dairy starter cultures, generate a variety of peptides from casein. Some of these casein-derived peptides are likely to alter intestinal cell kinetics. Effects on colon cell kinetics because of the presence of casein-derived peptides may be a mechanism through which fermented dairy foods reduce the risk of colon cancer. We have used two intestinal cell lines (IEC-6 cells, derived from normal rat intestine, and Caco-2 cells, derived from human colon adenocarcinoma) to identify casein peptides that affect intestinal cell kinetics. Cell culture media containing casein were inoculated with three commercial starter cultures and incubated for 4, 8, or 24h. The bacteria-conditioned media were then filter-sterilized and incubated with the intestinal cells for 6 or 24h. Rates of [3H]thymidine incorporation and cell cycle kinetics determined by flow cytometry were affected by the culture-modified media in both cell lines. The IEC-6 cells tended to reduce, and Caco-2 cells to increase, rates of cell division after exposure to the media. Intestinal cell response varied among the starter cultures. The results support the use of intestinal cell cultures to identify casein peptides generated by dairy starter cultures, which affect intestinal cell kinetics.

A review of traditional fermented foods, condiments and beverages in Nigeria: Their benefits and possible problems

This report presents a survey of traditional fermented foods, condiments and beverages consumed by various ethnic groups in rural Nigeria. Some of these foods have been reported elsewhere, while little or no information exists on others. The report describes their methods of preparation and consumption. Common fermented foods from local staples in Nigeria include cassava products (garri, fufu, elubo, abacha, akara akpu), yam products (amala), maize products (ogi, agidi, soy‐ogi), millet products (ogi‐baba, kwunu, tuwo, fura). The food condiments are dawadawa (African locust bean), ogiri‐ugu (fluted pumpkin), ogiri‐isi (castor seeds), ogiri‐egusi (melon seeds), ugba (African oil bean), ukwa (African breadfruit) daddawa (soy‐bean), eketeke (oil palm nut), as well as fermented meats and fish. The beverages include palmwine, ogogoro, pito, burukutu, maize beer, sorghum beer etc, while the fermented milk products are nono, maishanu and wara. These foods are produced on a small scale household basis. Most of these fermentations are natural, involve contact with appropriate inocula and are accomplished by the natural temperatures of the tropics. The benefits of fermentation include increased shelf life, removal of toxins, improvement in texture, taste, and flavour as well as increased nutritional value. Possible risks of consumption of fermented foods are also discussed.