Yeasts And Molds Research Articles

Effects of scents on airborne microbes, part I: thymol, eugenol, trans‐cinnamaldehyde and linalool

AbstractFour aroma chemicals, thymol, eugenol, trans‐cinnamaldehyde and linalool, were tested for their influence on total microbial count (bacteria, yeasts and moulds) in air. After determining both the total microbial count (TC) and the total count of yeasts and moulds (YM) of airborne microbes in a selected testing room, using a RCS Air Sampler, each of the aroma chemicals was vapourized in four different concentrations, 5, 2.5, 1.5 and 0.5 mg/m3. After a residence time of 15 min, the germ count in the testing room was measured again, using the air sampler. Each tested substance in any concentration showed a reduction of total microbial count as well as a reduction of total count of yeasts and moulds in the air and thus contributes to abating infection hazard for humans. The most effective concentrations for each substance were as follows. For total microbial count reduction: thymol, 1.5 mg/m3 (69.50% reduction); eugenol, 1.5 mg/m3 (69.40% reduction); trans‐cinnamaldehyde, 1.5 mg/m3 (65.93% reduction); and linalool, 2.5 mg/m3 (69.92% reduction). For total count reduction of yeasts and moulds: thymol, 0.5 mg/m3 (50.60%); eugenol, 1.5 mg/m3 (58.31%); trans‐cinnamaldehyde, 2.5 mg/m3 (46.19%); and linalool, 1.5 mg/m3 (50.25%). Copyright © 2006 John Wiley & Sons, Ltd.

STUDIES ON PREPARATION AND STORAGE CHARACTERISTICS OF ONION (ALLIUM CEPA L.)-CHILLY (CAPSICUM ANNUM) CHUTNEY

Traditionally, onion has been widely used in various culinary preparations. It has been used extensively in food production throughout India. Various products are made out of onions, both as the primary constituent and in combination with other vegetables and spices. One traditional food adjunct is onion–chilly chutney. Current studies are investigating shelf life and stability issues related to this product. A recipe for the preparation of onion–chilly chutney has been standardized, and it was analyzed for proximate composition and sensory characteristics. Sensory evaluation shows that the product is acceptable during 6 months of storage when held at room temperature. Microbiological analysis indicated that the total plate count (TPC) and yeast and mold count were within the permitted levels. TPC values decreased from 12 ¥ 10 3 cfu/g to <10 2 , and yeast and mold count was decreasing to zero levels during 6 months of storage period. Onion–chilly chutney prepared in this study contained acidity of 1.27%, pH 2.8, salt 9% and water activity of 0.86 and was found to be shelf-stable for 6 months at ambient storage conditions (approximately 28–30C).

COMPARISON OF MIKROCLAVETM STERILIZATION SYSTEM AND CONVENTIONAL AUTOCLAVING FOR THE STERILIZATION OF MICROBIOLOGICAL MEDIA 1

ABSTRACTThe viable cell count performance of nutrient agar prepared by the MikroClaveTM sterilization system MSS‐500 was evaluated using Escherichia coli 0157:H7, Salmonella typhimurium, and Yersinia enterocolitica with conventionally autoclaved media as a comparison. No significant difference was found between agar prepared by the two methods. The MikroClaveTM was able to sterilize common bacteriological media such as Eosin Methylene Blue (EMB) agar, nutrient agar, Yeast and Mold (YM) agar, lactose broth, nutrient broth, and Yeast and Mold (YM) broth.

Sampling of Microbial Aerosols at Various Locations in Fluid Milk and Ice Cream Plants

Potential sources of aerosol contamination and dairy products' containers in four commercial dairy plants (fluid milk and ice cream) were sampled for microorganism-containing particles and residual bacterial count (RBC), respectively, over a 3- month period. Microbiological analyses included total aerobes (TA), staphylococci (ST), and yeasts and molds (YM). The Biotest RCS sampler was used for air sampling. All aerosol sources sampled in this study indicated significant increase in the microbial content of the air when compared to air in plants without processing activity. However, when comparisons are made between exit air from the ventilation system (filtered air) and other aerosols sampled during processing activity, only the drains, water spraying, and personnel activity were associated with significant increases in TA and ST. Half and/or whole gallon retail containers were sampled 2 to 3 times per d in four plants. The RBC of containers from each of the four plants did not exceed one CFU per ml of capacity.

Comparison of the Petrifilm™ Yeast and Mold Culture Film Method to Conventional Methods for Enumerating Yeasts and Molds in Foods

Petrifilm™ Yeast and Mold (YM) plates were compared to acidified potato dextrose agar (APDA) and chloramphenicol-supplemented plate count agar (CPCA) for its suitability to enumerate yeasts and molds in 13 groups of food products. These products consisted of beans (dry and frozen, green), corn meal, flour (wheat), fruit (apple), a meat/vegetable entree (chicken pot pie), a precooked meat (beef), milk (dehydrated, nonfat), nuts (pecans), pasta, potatoes (dehydrated), precooked sausage, and a spice (black pepper). Correlation coefficients of Petrifilm™ YM plates versus APDA and CPCA pour plates for recovering total yeasts and molds from a composite of the thirteen test foods were, respectively, 0.961 and 0.974. Individually, Petrifilm™ YM plate counts were equivalent or higher than APDA and CPCA for some food groups and lower for other food groups. Because food particle interference can make enumeration of yeast and mold colonies on Petrifilm™ YM plates difficult for some food groups, potential food interference will need to be evaluated for each food group tested.

Evaluation of a Culture Film (Petrifilm™ YM) Method for Enumerating Yeasts and Molds in Selected Dairy and High-Acid Foods

The Petrifilm™ Yeast and Mold (YM) plate was compared to acidified potato dextrose agar (APDA) and chloramphenicol-supplemented plate count agar (CPCA) using pour- and surface-plating techniques for its ability to recover yeasts and molds from hard and soft cheeses, cottage cheese, yogurt, sour cream, fruit juice, salad dressing, relishes, and tomato-based sauces. Correlation coefficients of Petrifilm™ YM plates versus pour-APDA, surface-APDA, pour-CPCA, and surface-CPCA for recovering total yeasts and molds from a composite of the eight test foods were, respectively, 0.993, 0.993, 0.994, and 0.995. Slope and intercept values for populations detected using Petrifilm™ YM plates versus traditional systems ranged, respectively, from 0.984 to 1.008 and −0.051 to 0.149. The coefficient of variation for total yeast and mold populations recovered on Petrifilm™ YM plates was 1.0% compared to 1.2 to 1.7% for traditional enumeration systems. Regardless of the enumeration system employed or the type of fungal cell, i.e., yeast or mold, being enumerated, significantly (P ≤ 0.05) higher populations were generally detected after 5 d compared to 3 d of incubation. After 5 d of incubation, in no case were yeast or total yeast and mold populations detected in the eight food products using Petrifilm™ YM plates significantly lower than respective populations detected using traditional pour- and surface-plating techniques and media. When Petrifilm™ YM plates were used, significantly higher total yeast and mold populations were detected in 3, 1, and 1 out of eight food products compared to using, respectively, pour-APDA, surface-APDA, and surface-CPCA enumeration systems. The Petrifilm™ YM plate offers an acceptable alternative to traditional methods for enumerating yeasts and molds in the dairy and high-acid products evaluated in this study.

Design and use of 10-kc source of cobalt-60: Akibumi Danno, Japan Atomic Energy Research Institute, Tokai, Ibaraki, Japan

Recently the applications of the low starch contents of yam mucilage in nutraceutical and cosmeceutical industries are required. A novel continuous pilot-scale bubble separation system was used for recovering yam slurry mucilage. The objectives of these studies were to follow the previous design for continuously separating, recovering and irradiating yam slurry mucilage for inactivation of microorganisms. The UV-C dose of 32000 μW/sec/cm2 at 254 nm has a germicidal effect against microorganisms and is used for the disinfection. Two sets of custom made UV-C irradiators containing four UV-C germicidal lamps were added to the system. The effectiveness of this UV-C irradiator for reducing the aerobic bacteria count (APC) and yeasts and molds (YM) count in yam slurry mucilage was investigated. The results showed UV-C irradiation was successfully applied to reduce the microbial load in the yam slurry mucilage. If the slurry mucilage completes the process for both two sets of UV-C irradiators, a 4.5 log10 APC reduction and a 4.1 log10 YM reduction were achieved after 200 sec irradiation at a UV-C dosage of 32000 μW/sec/cm2, resulting in zero cfu/ml APC and YM. Escherichia coli and Salmonella are both negative. This novel continuous UV-C pilot-scale bubble separation technology could be an alternative technology not only separate and recover mucilage but also reduce the microorganisms to acceptable levels.This novel continuous pilot-scale bubble separation system was used for recovering yam slurry mucilage. Recently the applications of the low starch contents of yam mucilage in nutraceutical and cosmeceutical industries are required.This novel continuous UV-C pilot-scale bubble separation technology could be an alternative technology not only to separate and recover mucilage but also reduce the microorganisms to acceptable levels. Actually the pilot scale of this system is going to build in our university. We also try to further use it for non-thermal fermentation. There are many potential industrial applications using this idea.