Jerry N. Cash

A comparison of different chemical sanitizers for inactivating Escherichia coli O157:H7 and Listeria monocytogenes in solution and on apples, lettuce, strawberries, and cantaloupe.

Ozone (3 ppm), chlorine dioxide (3 and 5 ppm), chlorinated trisodium phosphate (100- and 200-ppm chlorine), and peroxyacetic acid (80 ppm) were assessed for reduction of Escherichia coli O157:H7 and Listeria monocytogenes in an aqueous model system and on inoculated produce. Initially, sanitizer solutions were inoculated to contain approximately 10(6) CFU/ml of either pathogen, after which aliquots were removed at 15-s intervals over a period of 5 min and approximately plated to determine log reduction times. Produce was dip inoculated to contain approximately 10(6) E. coli O157:H7 or L. monocytogenes CFU/g, held overnight, submerged in each sanitizer solution for up to 5 min, and then examined for survivors. In the model system study, both pathogens decreased > 5 log following 2 to 5 min of exposure, with ozone being most effective (15 s), followed by chlorine dioxide (19 to 21 s), chlorinated trisodium phosphate (25 to 27 s), and peroxyacetic acid (70 to 75 s). On produce, ozone and chlorine dioxide (5 ppm) were most effective, reducing populations approximately 5.6 log, with chlorine dioxide (3 ppm) and chlorinated trisodium phosphate (200 ppm chlorine) resulting in maximum reductions of approximately 4.9 log. Peroxyacetic acid was the least effective sanitizer (approximately 4.4-log reductions). After treatment, produce samples were stored at 4 degrees C for 9 days and quantitatively examined for E. coli O157:H7, L. monocytogenes, mesophilic aerobic bacteria, yeasts, and molds. Populations of both pathogens remained relatively unchanged, whereas numbers of mesophilic bacteria increased 2 to 3 log during storage. Final mold and yeast populations were significantly higher than initial counts for chlorine dioxide- and ozone-treated produce. Using the nonextended triangle test, whole apples exposed to chlorinated trisodium phosphate (200 ppm chlorine) and shredded lettuce exposed to peroxyacetic acid were statistically different from the other treated samples.

Chlorine and ozone washes for pesticide removal from apples and processed apple sauce

Abstract The effectiveness of chlorinated and ozonated water dips in the dissipation of azinphos-methyl, captan and formetanate hydrochloride in solution and on fresh and processed apples was examined. All three pesticides in model systems solution decreased 50–100% with chlorine and ozone treatment. Captan and formetanate-HCl were both rapidly degraded in 50 and 500 mg liter −1 chlorine solutions at pH 7 and 10.7. Ozonation was also effective in degrading the pesticides. Rate of degradation of the pesticides generally increased at higher pH and temperature. Pesticide residues on fresh apples and in processed products were also reduced by chlorine and ozone washes; chlorine (500 mg liter −1 ) being the most effective wash treatment. Ozone wash at 0.25 mg liter −1 was not as effective owing to its low concentration, its instability in water and the high organic content of the wash water.

Influence of cultivar, harvest-date and soil nitrogen on sucrose, specific gravity and storage stability of potatoes grown in Michigan

The cultivars Atlantic, Belchip, Denali, Monona, Norchip and Russet Burbank were harvested at weekly intervals from early August to early October in 1980–81 and analyzed for the following attributes: 1) sucrose rating (SR) (mg sucrose/g fresh tuber) 2) specific gravity (Sp.G.); 3) total yield and 4) chip color. At the final harvest, samples of each cultivar were stored and analyzed for color to determine chipping ability after storage.All varieties achieved a SR below 1.0 by 145 days of growth. Higher nitrogen levels reduced the total yield for early harvests but had no significant effect for later harvests. Changes in sucrose levels as tubers matured were helpful in evaluating the chemical maturity of more recently developed cultivars in relation to established chipping varieties.ResumenLos cultivares Atlantic, Belchip, Denali, Monona, Norchip y Russet Burbank fueron cosechados a intervalos semanales desde principios de Agosto hasta principios de Octubre, en 1980–1981, y analizados para las siguientes características: 1) nivel de sucrosa (SR) (mg de sucrosa/gramo de tubérculo fresco); 2) gravedad específica (Sp.G.); 3) rendimiento total, y 4) color de los cortes. A la cosecha final, se almacenaron muestras de cada cultivar y se analizaron por su color para determinar su aptitud al corte después de su almacenamiento.Todas las variedades alcanzaron un SR por debajo de 1,0 alrededor de 145 días de crecimiento. Los niveles más altos de nitrógeno redujeron el rendimiento total en las cosechas tempranas, pero no tuvieron efecto significativo en las cosechas más tardías. Conforme los tubérculos maduraban, los cambios en los niveles de sucrosa fueron una ayuda para evaluar la madurez química de cultivares más recientemente desarrollados en relación con las variedades ya establecidas para la producción de papas para freir a la inglesa.

Differences in sugars, chip color, specific gravity and yield of selected potato cultivars grown in michigan

Six cultivars, Atlantic, Eramosa, Kanona, Norchip, Onaway and Saginaw Gold and four selections, MS 700-70, MS 700-83 (Spartan Pearl), MS 716-15 and W-855 (Snowden), were analyzed for sucrose, glucose, chip color, specific gravity and yield at 98 and 138 days in 1988 and 1989, t evaluate their performance to Michigan growing conditions. The average yield of these cultivars at the two harvests for 1988 and 1989 was 46.9 and 54.7 t/ha and 43.1 and 52.3 t/ha, respectively. Eramosa and Onaway were the earliest maturing varieties with low specific gravity, high glucose content and processed into dark colored chips. The glucose and sucrose contents of the remaining eight cultivars at each harvest date were low and produced acceptable chips. The specific gravity of Atlantic, MS 700-70, MS 716-15 and W-855 was in the range of 1.079–1.088 and for Norchip, Kanona and Saginaw Gold the range was 1.071–1.076. The date of harvest, variety and year of production had significant effect (p > 0.01) on yield. The specific gravity, glucose content and chip color were significantly influenced by variety and year of production. The correlation between chip colorvs glucose (r= -0.842, p = 0.000) and harvest datevs yield (r= -0.572, p = 0.000) was also significant.

Pyruvate and flavor development in macerated onions (Allium cepa L.) by γ-glutamyl transpeptidase and exogenous C-S lyase

Abstract Effect of γ-glutamyl transpeptidase in conjunction with exogenous C-S lyase on pyruvate content in macerated onion and flavor profile was studied. Pyruvate production of 2.5-fold greater than that of the control was obtained in γ-glutamyl transpeptidase and exogenous C-S lyase treated onions held for 20 h at 37 °C. Relative abundance of flavor compounds in Spartan Banner, a pungent onion, varied from a yellow sweet salad-type onion. The effect of γ-glutamyl transpeptidase and exogenous C-S lyase on onion flavor profile was shown by a shift of major components from methyl propyl disulfide, methyl propenyl trisulfide, dimethyl tetrasulfide and propyl 1-propenyl trisulfide, into new major components, methyl 1-propenyl disulfide, dipropyl disulfide, propyl 1-propenyl disulfide, methyl 1-propenyl trisulfide, and propyl 1-propenyl trisulfide. This increase in 1-propenyl containing flavor compounds may effect overall flavor of γ-glutamyl transpeptidase and exogenous C-S lyase treated onion extracts.

The Decomposition of Daminozide (Alar) to Form Unsymmetrical Dimethylhydrazine (UDMH) in Heated, pH Adjusted, Canned Solutions

Processing conditions were chosen to determine the influence of temperature, pH, and processing on model solutions containing daminozide residues. Daminozide (succinamic acid 2, 2-dimethylhydrazide) fortified solutions (12.5 ppm) containing 50mM NaH2PO4 and 24% sucrose (w/w) were adjusted to pH 3.0, 3.6, or 4.0 and either heated (100°C) for 0, 5, 10, or 15 min in sealed cans and cooled or heated (80°C) for 0, 5, or 10 min in open cans, sealed, heated (100°C) for 5 min, and cooled. Daminozide degradation due to heating was less than the HPLC detection limit (1.5 ppm) for all of the treatments. Unsymmetrical dimethylhydrazine (UDMH) concentration was significantly affected by heating time, pH, and processing. Heating of daminozide solutions in sealed cans produced approximately 1 ppm of UDMH for every minute of heating at 100°C. Heating of daminozide solutions in open cans at 80°C resulted in simultaneous production of UDMH in the solution and loss of UDMH through volatilization. Maximum degradation of daminozide was observed at pH 3.6.