Thirty-two essential oils from plants were screened for inhibitory effects on 13 food-spoilage and industrial yeasts. Of these, essential oils of allspice, cinnamon, clove, garlic, onion, oregano, savory, and thyme were most inhibitory. Oils were subsequently tested for their effects on biomass production and pseudomycelium formation of eight genera of yeasts. Garlic oil was a potent inhibitor of yeast growth at concentrations as low as 25 ppm. The oils of onion, oregano and thyme were also strongly inhibitory. Essential oils (100 ppm) had no effect on pseudomycelium production by Candida Zipolytica. However, all eight essential oils delayed pseudomycelium formation by Hansenula anomafa, whereas six oils stimulated pseudomycelium production by Lodderomyces elongisporus. Cinnamon and clove oils were clearly stimulatory to pseudomycelium production by Saccharomyces cerevisiae.

The effect of pH reduction with acetic (pH 5.2), citric (pH 4.0), lactic (pH 4.7), malic (pH 4.0), mandelic (pH 5.0), or tartaric (pH 4.1) acid on growth and survival of Escherichia coli O157:H7 in tryptic soy broth with 0.6% yeast extract held at 25, 10, or 4؇C for 56 days was determined. Triplicate flasks were prepared for each acid treatment at each temperature. At 25؇C, populations increased 2 to 4 log 10 CFU/ml in all treatments except that with mandelic acid, whereas no growth occurred at 10 or 4؇C in any treatments except the control. However, at all sampling times, higher (P < 0.05) populations were recovered from treatments held at 4؇C than from those held at 10؇C. At 10؇C, E. coli O157:H7 was inactivated at higher rates in citric, malic, and mandelic acid treatments than in the other treatments. At the pH values tested, the presence of the organic acids enhanced survival of the pathogen at 4؇C compared with the unacidified control. E. coli O157:H7 has the ability to survive in acidic conditions (pH, Ն4.0) for up to 56 days, but survival is affected by type of acidulant and temperature.

Ninety-six weanling pigs (initial BW = 9.3 kg, initial age = 37 d) were used in a 4-wk experiment to evaluate the response to three Ca: total (t) P ratios (1.2:1, 1.6:1, or 2.0:1) fed in combination with two P levels (.07 or .16% available that correspond to .36 or .45% tP) and two phytase levels (PY; 700 or 1,050 units/kg of diet). A 3 x 2 x 2 factorial arrangement of treatments was employed using a corn-soybean meal diet. Performance, serum mineral concentrations and alkaline phosphatase (ALP) activity, Ca and P digestibility and excretion, and bone mechanical measurements were examined. Average daily gain (P < .001), average daily feed intake (P < .01), and gain:feed (P < .05) were decreased linearly as the Ca:tP ratio became wider. The digestibility of P and Ca were decreased (P < .001) linearly as the Ca:tP ratio became wider. The digestibility of P (P < .001) and fecal P excretion (P < .01) were increased at the higher level of P. Increasing PY from 700 to 1,050 units (U)/kg of diet increased (P < .05) P digestibility and decreased (P < .01) P excretion but did not improve bone measurements. Shear force, stress and energy, and percentage of ash of both metacarpal and 10th rib linearly decreased (P < .001 to .05) as the Ca:tP ratio became wider, and bone measurements were generally greater for pigs fed the higher P level. Serum Ca concentration increased (P < .01) and the P concentration decreased (P < .001) as the Ca:tP ratio increased, but Mg, Zn, and ALP activity were not influenced by the Ca:tP ratio. Serum Ca and P concentrations were affected by PY supplementation over the 4-wk trial, but serum Mg and Zn concentrations were not affected by dietary treatments. Adverse effects of a wide Ca:tP ratio were greater at the low P diet for all responses. In addition, the activity of supplemental PY in diets seemed to be decreased as the Ca:tP ratio became wider and this negative effect of Ca:tP ratio seemed greater at the low P level, and seemed to parallel the effects of Ca:tP ratio on performance, P digestibility, bone, and serum measurements. Narrowing the dietary Ca:total P ratio from 2.0:1 to 1.2:1 led to an approximate 16% increase in phytase efficacy for improving performance, digestibility, bone measurements, and serum Ca levels.

The effects of fat level and low fat formulation on survival of Escherichiu coli 0157:H7 isolate 204P heated in ground beef [7%, 10% and 20% fat], pork sausage [7%, lo%, and 30% fat], chicken (3% and 11% fat), and turkey (3% and 11% fat) were determined by D-and z-values. D-values for E. coli 0157:H7 in lowest fat products were lower than in traditional beef and pork products (P < 0.05). Overall, higher fat levels in all products resulted in higher D-values. D,, values (min) ranged from 0.4550.47 in beef, 0.37-0.55 in pork sausage, 0.38-0.55 in chicken and 0.5550.58 in turkey. D,, and D,, values were respectively longer. Zvalues ranged from 4.44.8"C. Product composition affected lethality of heat to E. coli 0157:H7.

The bactericidal activity of 0.5, 1,2,4, and 6% acetic, citric, lactic, malic, mandelic, propionic, or tartaric acid was determined against Salmonella typhimurium that were loosely or firmly attached to broiler chicken skin by using the skin-attachment model. Acid treatments were applied during a simulated chill (0°C/60 min), postprocess dip (23°C for 15 s), or scald (50°C for 2 min). For comparison, activity of the acid treatments when applied under these conditions were also determined against S. typhimurium in aqueous suspension. In general, bactericidal activity (mean reduction log CFU per skin) of all acids increased linearly with increasing concentration in all applications. The bactericidal activity of organic acids depended on concentration and method of application. When compared to freely suspended cells, it is clear that salmonellae both firmly and loosely attached to poultry skin have increased resistance to or are protected from organic acids. In general, concentrations of ≥4% of the acids were required to kill ≥2 log number of cells of S. typhimurium that were attached to broiler skin.