Effect of Consuming Yogurts Prepared with Three Culture Strains on Human Serum Lipoproteins

Ten human adult males' usual diets were modified by incorporating 681g nonfat, unpasteurized yogurt daily throughout three 14-21 day periods. A different set of select culture strains, two commercial and one patented, were used for yogurt production in the three dietary periods. Including yogurt daily in the diet significantly reduced fasting total serum cholesterol 10-12% in human adult males on some days, but serum cholesterol returned towards control values with continued yogurt consumption. Serum triglycerides and the proportions of serum lipoproteins were not significantly influenced by increasing yogurt consumption. Differences in concentrations of uric, orotic and hydroxymethylglutaric-like acids in the yogurts were insufficient to account for the differences in temporary hypocholesterolemic effects of yogurt consumption seen between strains.     

Effects of Short-term Exposure to Low O2 and High CO2 Atmospheres on Quality Attributes of Strawberries

Strawberries (Fragaria ananassa Duch., cv. ‘Selva') were stored 10 days in 1.0%, 0.5%, or 0.25% 0₂ or air + 20% CO₂; or 6 days in air + 50% or 80% CO₂ at 0 or 5°C without detrimental effects on quality. Decay and softening were reduced by treatments. An untrained taste panel, under ordinary eating conditions, did not consistently differentiate ‘Pajaro’ strawberries kept in 0.25% 0₂ from those stored in air. A trained taste panel, under controlled conditions, perceived slight off-flavor in ‘G3’ strawberries kept in 0.25% or 0% 0₂. This correlated with ethanol, ethyl acetate, and acetaldehyde in juice. The 50% or 80% CO₂ treatments caused injury after 8 to 10 days, while 20% CO₂ treatments did not. All high CO₂ treatments caused increase in pH of juice.     

Resistance of Clostridium perfringens to Varying Degrees of Acidity during Growth and Sporulation

SUMMARY: Viable cells of each of 6 strains of Clostridium perfringens were exposed to 4 levels of acidity during phases of the growth cycle. The selected strains included 4 which had been recovered in association with food poisoning outbreaks and 2 strains not so associated. The growth media tested included Fluid Thioglycollate Medium, DS-sporulation medium and the CP-2V medium proposed by Hauschild.
The level of acidity, length of exposure of the cells, the growth medium employed and the phase in the growth curve influenced the survival of C. perfringens. Exposure of cells grown in DS-sporulation medium to buffers pH 6.0 had little effect on the survival over the 8-hr test period, with somewhat greater sensitivity of cells being demonstrated at pH 4.5. Exposure of cells, similarly produced, to buffer pH 1.0 or 2.0 was much more effective in reducing the percentage of survival, particularly during early log phase and at the onset of sporulation. Based on the 3 growth media utilized, calculated survival curves resulting from exposure of cells to pH 1.0 or 2.0 were erratic in shape, and percentage survival was almost universally less than 10%.
Source of the strain, whether food poisoning or non-food poisoning associated, appeared to have no significant effect on the acid resistance of the cells. The comparatively regular increase in the percentage of survivors after the initiation of sporulation suggests that spores exhibit a greater resistance to acid stress than vegetative cells.
Incubation at temperatures of 37° or O°C, during the time of treatment with the test buffers pH 1.0 or 2.0, produced no consistent change in the percentage of survivors when the cells were grown in FTG.     

COMPARISON OF RECOVERY METHODS FOR CLOSTRIDIUM PERFRINGENS FROM SELECTED FOODS1, 2

Ground beef, extruded soy protein (ESP), and ESP extended ground beef were analyzed for Clostridium perfringens by several isolation techniques. C. perfringens was isolated by one or more of nine procedures from 68% of all units analyzed. One or more of the four isolation temperatures when samples were blended and one or more of the four temperatures when samples were not blended detected C. perfringens in 60 and 59% of the units, respectively. Incubation of fluid thioglycollate media (FTM) at 37 and 46°C resulted in a significantly higher isolation rate than all other methods, with blended samples incubated at 46°C being the most practical. Heat shocking samples at 75 and 95°C yielded only two isolates not isolated at 37 or 46°C. Direct inoculation of sulfite polymyxin sulfadiazine agar pour plates showed only 40% of all units analyzed contained C. perfringens. C. perfringens was isolated from 85, 23, and 94% of the ground beef, ESP, and ESP extended ground beef units, respectively.     

NOVEL NONTHERMAL METHODS TO REDUCE VIBRIO VULNIFICUS IN RAW OYSTERS

Vibrio vulnificus is a foodborne pathogen associated with consumption of raw oyster. No scientific data is available on postharvest treatments of oyster by ultrasound, ozone, and organic acids. This study was designed to investigate the effects of these treatments on inactivation of V. vulnificus naturally present in the in-shell or half-shelled oysters. In in-shell oysters, these treatments were not effective in reducing the number of this pathogen. Half-shelled oysters treated with ultrasound, and ozone in 2% saline for 30 min had 1 and 1.5 log less V. vulnificus, respectively (p<0.05). Treatment of half-shelled oysters by 50 and 100% lemon juice, 5% citric acid, 10% citric acid, or vinegar for 30 min resulted in a significant reduction (2–4 log) in the numbers of V. vulnificus (p<0.05). Although these methods significantly reduced the population of V. vulnificus in raw oysters, they were not able to reduce the numbers of this pathogen to acceptable level (<3 MPN/g).     

Cyanobacterial (Blue-Green Algal) Toxins and their Significance in UK and European Waters

The cyanobacteria (blue-green algae) which commonly produce mass developments in fresh and saline waters are capable of producing toxins. These compounds have been responsible for the deaths of animals, birds and fish in many countries, and have been linked with several forms of human illness through skin contact and ingestion. Evidence has accumulated over the past decade that cyanobacterial toxins occur commonly in European waters which contain cyanobacterial mass growths. This paper summarizes the recent published occurrence and types of cyanobacterial toxins found in European waters with reference to poisoning incidents.
Cyanobacterial blooms were particularly abundant in the warm dry summer of 1989 in the UK. The deaths of sheep and dogs and the cases of human illness that were ascribed to cyanobacterial toxins were followed by a more intensive and wider investigation into the extent of cyanobacterial toxicity in UK waters than had hitherto been undertaken. Of the cyanobacterial blooms sampled from over 90 freshwaters, approximately two-thirds were toxic (lethal) according to mouse bioassay. Short-term and long-term needs for the recognition, quantification and management of problems which can be caused by potentially toxigenic cyanobacteria in water-bodies used for recreation, aquaculture and potable supply are briefly discussed.