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Biomedical subjects

M J Nout

Publications and source records attributed to M J Nout.

24 records · Page 2Linked to original sources
PubMed1991

Ecology of accelerated natural lactic fermentation of sorghum-based infant food formulas.

Accelerated natural lactic fermentation of mixed sorghum-cowpea (Formula 1) and sorghum-milkpowder (Formula 2) infant food formulas was achieved by repetitive (60 fermentation cycles of 24 h each) use of the previous batch as an inoculum at a rate of 10% (w/w) and resulted in a gradual establishment of mixed populations of lactic acid bacteria and yeasts. In Formula 1, early fermentation stages (fermentation cycles 1-4) were dominated by Leuconostoc and Lactococcus spp. which caused conditions inhibitive to yeasts. Probably due to micronutrient deficiencies, the former lactic acid bacteria were succeeded by a combination of Lactobacillus plantarum and Candida spp. achieving pH values 4.2-4.3. In formula 2, Lactobacillus acidophilus, Lactococcus lactis and Lactobacillus brevis consistently achieved pH 3.7-3.8, thereby allowing only a minority of yeasts, mainly Candida and Trichosporon spp. None of the isolated yeasts exhibited 'killer'-activity.

Animals↗
PubMed1990

Toxicological, nutritional and microbiological evaluation of tempe fermentation with Rhizopus oligosporus of bitter and sweet apricot seeds.

Bitter and sweet apricot seeds are by-products of the apricot processing industry. Bitter seeds, in particular, contain toxic levels of the cyanogenic substance amygdalin. Tempe was made from both kinds of seeds. The bitter seeds contain antimicrobial substances which must be removed by leaching and boiling prior to tempe fermentation. Apricot seed tempe had an agreeable taste. It contained approx. 21% (w/w) crude protein, 52% (w/w) crude fat, 1.5% (w/w) crude fibre and 25.5% (w/w) carbohydrates based on dry matter. The extent of biological acidification during soaking prior to fungal inoculation was inadequate to prevent growth of Bacillus cereus, and requires further optimisation. Bitter seeds were detoxified by the tempe process (approx. 70% of total cyanide was removed). However, additional improvement of the detoxification process is required to obtain a completely safe product.

Amygdalin↗
PubMed1989

Effect of accelerated natural lactic fermentation of infant food ingredients on some pathogenic microorganisms.

Accelerated natural lactic fermentation in mixtures of water and ground sorghum, millet and pigeon pea was obtained by gradual selection of lactic acid bacteria, through inoculum recycling. Weaning food prepared from ingredients fermented this way, contained approx. 0.7% lactic and 0.05% acetic acids and had a pH of about 3.8. In porridges, a pH of less than or equal to 4.0 was required to cause death of Salmonella typhimurium and Staphylococcus aureus. Several intestinal pathogenic bacteria were inoculated into sour porridge. The most resistant Salmonella sp. died at a rate of 1.2 log cycle/h; the most resistant Shigella sp. at 0.9 log cycle/h; and the most resistant Escherichia coli strain at 0.6 log cycle/h. A yeast, Candida albicans, could grow well in the sour product, whereas a bacteriophage (MS-2) was inactivated at a rate of 0.1 log cycle/h. In the acid-sensitive bacterial cultures, no gradual adaptation to acid environments could be observed. The survival studies were carried out at 30 degrees C.

Bacteria↗
PubMed1988

Effect of environmental conditions during soya-bean fermentation on the growth of Staphylococcus aureus and production and thermal stability of enterotoxins A and B.

During tempe manufacture, Staphylococcus aureus was able to survive in newly started soya-bean soaks (final pH 4.7), whereas it died during soaks with accelerated souring (final pH 4.0). No S. aureus were detected after subsequent heat treatment of soaked beans. S. aureus strain S6 could produce enterotoxins A and B if inoculated on cooked soya-beans. Its growth and enterotoxin production were not influenced by inoculation rate nor by the presence of actively growing Rhizopus oligosporus, the fungus responsible for tempe formation. Enterotoxin levels were highest after 48 h fermentation. Presence of lactobacilli (L. brevis or L. plantarum) during the tempe fermentation did not influence staphylococcal growth, but enterotoxin levels were reduced. Reduced oxygen pressure did not affect staphylococcal growth, but resulted in lower enterotoxin levels after 48 h incubation. The thermal stability of enterotoxin A in tempe was significantly lower than in Brain Heart Infusion broth of comparable pH. Heating of enterotoxin-containing tempe mash reduced enterotoxin A by 99.7% as measured with ELISA and animal feeding methods.

Animals↗
PubMedDate not supplied

Investigation of the presence of biogenic amines and ethyl carbamate in kenkey made with maize and maize-cowpea mixtures as influenced by process conditions.

Kenkey is a fermented and cooked maize dough from Ghana. The effect of manufacturing conditions, i.e. fermentation and cooking, and of protein-enrichment by cowpea addition (20% of total weight) on the occurrence of toxic microbial products, namely biogenic amines and ethyl carbamate, were investigated. The levels of biogenic amines in all-maize kenkey were very low (total amines < 60 ppm), but were significantly increased by addition of red cowpea (total amines < 200 ppm, mainly cadaverine and tyramine), and even more by white cowpea (total amines < 500 ppm, mainly putrescine and tyramine). Histamine was absent (< 5 ppm) in all samples. The effects of fermentation and cooking were less pronounced than the influence of cowpea addition. Prolonged cooking of kenkey resulted in lower levels of putrescine, but did not significantly reduce tyramine levels. Ethyl carbamate levels were negligible (< 11 ppb) in all treatments.

Biogenic Amines↗