Yeast-mould Counts Research Articles

Quality profile of litchi ( Litchi chinensis) cultivars from India and effect of radiation processing

Litchi ( Litchi chinensis) is a non-climacteric tropical fruit. The fruit has a short shelf-life making its marketing difficult. Physical, biochemical, microbiological, and organoleptic properties of two major commercially grown Indian cultivars of litchi, ‘Shahi’ and ‘China’ were studied. The effect of gamma radiation processing and low temperature storage on the above parameters was evaluated to standardize the optimal process parameters for shelf-life extension of litchi. Physical and biochemical parameters analyzed included weight, moisture, pH, titratable acidity, texture, color, total and reducing sugar, total soluble solids, vitamin C, and flavonoid content. Weight, moisture content, and pH in the fresh fruit ranged between 21–26 g, 74–77%, and 3.7–4.4, respectively, whereas, total and reducing sugar ranged 10–15, and 10–13 g%, respectively. In ‘Shahi’ vitamin C content was found to be around 17–19 mg%, whereas, in ‘China’ it was 22–28 mg%. Flavonoid content was in the range of 26–34 μg catechin equivalents/g of fresh fruit. Total surface and internal bacterial load was around 4 and 3 log cfu/g, respectively. Surface yeast-mold count (YMC) was ∼3 log cfu/g whereas internal YMC was ∼2 log cfu/g. Radiation treatment reduced microbial load in a dose dependent manner. Treatment at 0.5 kGy did not significantly affect the quality parameters of the fruit. Treated fruits retained the “good” organoleptic rating during storage. Thus, radiation treatment (0.5 kGy) in combination with low temperature (4 °C) storage achieved a shelf-life of 28 days for litchi fruit.

Determination of microbial contamination sources at a Frankfurter sausage processing line

This study was conducted to determine microbial contamination sources during sausage processing. The samples were taken at 6 different stages of the sausage processing line in a local plant. Minced meat, sausage batter, stuffed sausage, cooked sausage, peeled sausage, and pasteurized sausage samples were examined microbiologically. Moreover, spices and ice water used in production, personnel hands, and equipment were examined. Counts of total aerobic mesophilic bacteria, Staphylococcus aureus, Escherichia coli, yeasts, and molds in minced meat were found to be 7.02, 3.83, 4.42, and 1.62 log cfu/g, respectively. E. coli and yeast-mold counts in sausage batter reached 3.99 and 1.72 log cfu/g, respectively. Heating for cooking was effective in reducing microbial counts. Total plate (3.93 log cfu/g) and S. aureus (1.08 log cfu/g) counts in cooked sausages decreased; E. coli and yeast-mold were not detected. According to the results, raw material and spices were found as primary contamination sources. Personnel hands and equipments were found as secondary contamination sources. Microbial counts in personnel hands showed significant correlations with the counts of the samples taken from all processing stages. Microorganism counts determined in overall processing were not at harmful levels for human health and the microbial load of the final product was within critical limits.

Some chemical and microbiological properties of ghee produced in Eastern Anatolia

Some properties of 30 ghee samples produced in Eastern Anatolia in Turkey were evaluated. Lipolytic bacteria and yeast–mould counts ranged from undetectable to 9.9 × 105 and 6.9 × 105 cfu/g, respectively. Most of the samples showed higher free fatty acids (FFA) and peroxide values (PV) than the limits mentioned in International Dairy Federation standards. Storage at 5°C for 30 days was not sufficient to stop the lipolytic and yeast–mould growth and lipid oxidation of the samples. Ghee samples with considerably higher trans ‐C18 : 1 and trans ‐C18 : 2 fatty acids contents were considered to be adulterated with hydrogenated oils. It is recommended that specific attention should be given to technology transfer and the education of traditional dairy product manufacturers.

Effect of Sorbic Acid and Potassium Sorbate Addition to the Brine on Microbiological and Chemical Properties of Turkish White Cheese during Ripening

In this study, the basic microbiological and chemical properties of Turkish white cheese, containing 300 ppm, 500 ppm and 700 ppm sorbic acid and potassium sorbate, ripened in brine for 90-days at 4 ± 1°C were investigated. Amount of sorbic acid and potassium sorbate added to the brine and ripening time had a significant impact on dry matter, fat, salt, salt in dry matter, titratable acidity, protein, water soluble nitrogen and the concentration of preservatives in cheese (p<0.01).During ripening, preservative diffusion to cheese significantly affected total aerobic mesophilic bacteria, coliform bacteria, and yeast-mould counts of cheese (p<0.01). Results indicated that sorbic acid and potassium sorbate could successfully be used as preservative agents in production of white cheese.

Selected Microbiological Properties of Kashar Cheese Samples Preserved with Potassium Sorbate

Kashar cheese, traditionally produced, is a popular dairy product in Turkey. Kashar cheese—a hard cheese—is frequently contaminated with mould. Potassium sorbate can be used for preservation of Kashar cheese. In this article, the effect of potassium sorbate on the microbiological characteristics of Kashar cheese was studied. It was found that the microbial counts at stored at 4 ± 0.1°C for 12 and 24 hours were not different from that of fresh milk samples. The means of total aerobic mesophilic bacteria (TAMB), lactic acid bacteria (LAB), coliforms, Staphylococcus aureus, proteolytic microorganisms, lipolytic bacteria, psychrotrophic bacteria and yeast-moulds in the cheese samples were determined as 4.3 × 107, 2.1 × 105, 3.5 × 10, 1.2 × 10, 4.5 × 105, 5.6 × 104, 1.7 × 103, and 4.8 × 104 cfu/g, respectively. The addition of potassium sorbate to Kashar cheese decreased the coliform and yeast-mould counts. The yeast and mould counts of cheese samples with added dry potassium sorbate were lower than that of fluid potassium sorbate.

Chemical, microbiological and sensory changes associated with fish sauce processing

The production of sardine fermented fish sauce was replicated in the laboratory in order to study the chemical, microbiological and sensory changes associated with the process. Fish sauce were produced by incubating mixtures of sardine (Sardina pilchardus) at different concentrations of sodium chloride and glucose at 37 °C for 57 days. Changes in chemical composition (moisture, protein, fat contents), pH, total volatile basic nitrogen (TVB-N, mg N/100 g fish flesh), trimethylamine (TMA-N, mg/100 g fish flesh), thiobarbituric acid (TBA, mg malonaldehyde/kg fish flesh), water activity (aw), color measurement, total viable count, lactic acid bacteria count, yeast and moulds counts and sensory analyses were observed. The fish sauces with spices were determined lower bacteria counts than fish sauces without spices. The addition of glucose to the fish sauces caused a significant increasing in the bacterial counts. Staphylococcus aureus and yeast-mould counts were not detected during fermentation period. The use of spices in fermentation of sardine enhanced good color, aroma and taste.

The Microbiological and Chemical Quality of Orgu Cheese Produced in Turkey

The chemical composition and microbiological properties of Orgu cheese, locally produced in Turkey, was investigated. The moisture, fat, protein, salt and % acidity were 52.25, 17,86, 19.96, 5.32 and 1.11% respectively while coliform, TAMB, LAB, Lipolytic and proteolytic microorganisms and yeast-mould counts were 3.73, 6.89, 6.78, 5.29, 4.50 and 5.45 cfu/gin success in cheese samples.

The Microbiological and Chemical Quality of Sikma Cheese Produced in Turkey

In this study, 34 sikma cheese samples, collected from Kahramanmaras province of Turkey were investigated and revealed that they contained 53% dry-matter (DM), 43.87% fat in DM, 20.25% protein, 3.28% WSP, 6.12% salt in DM. The average titre table acidity and ripening degree were 1.71 and 17.05% respectively. The coliform, TAMB, LAB, Lipolytic and proteolytic microorganisms and yeast-mould counts were 5.99, 7.82, 7.01, 5.73, 4.56, 5.03 log cfu/g in success in cheese samples.

Microbiological quality of fresh leafy vegetables, salad components and ready-to-eat salads: an evidence of inhibition of Listeria monocytogenes in tomatoes

A total of 116 samples of 11 different fresh vegetables from a local market generally consumed in raw form as well as 12 samples of ready-to-eat green salads procured from three grade 1 and 2 restaurants in Mumbai, India were examined for overall microbial quality in terms of bacterial, mold and coliform levels and incidence of pathogens such as Listeria and Yersinia. Standard procedures and media were used for isolation and identification studies. Thoroughly washed samples of 26 leafy vegetables, 12 roots, 62 tomatoes and four samples each of cabbage, capsicum and cucumber showed total bacterial and yeast-mold count in 106-107 cfu/gm and 102-105 cfu/gm range respectively. On the other hand, higher range of bacterial (106-108 cfu/gm) and mold (104-107 cfu/gm) count were noticed in ready-to-eat salads from restaurants. The MPN index/gm for coliforms for vegetables from a local market ranged from <3 to >1100 whereas for ready-to-eat salads it was 11 to 460. Evidence of higher number of coliforms was observed mostly in green leafy vegetables. All (100%) local vegetables exhibited the incidence of Listeria and Yersinia. On the other hand, ready-to-eat salads showed 20 and 73% presence of Yersinia and Listeria respectively. Higher occurrence of fecal coliforms was (65.6%) found in raw vegetables while they were absent in ready-to-eat salad samples. Non-pathogenic species like Y. intermedia and L. innocua were predominating species in most of the samples. Nevertheless, presence of L. monocytogenes was observed in 7 out of 62 tomatoes, 5 out of 10 coriander leaves, 2 out of 4 spinach samples and one from 4 cabbage samples. Studies conducted to understand the ability of L. monocytogenes 036 and 35152 to grow in tomato in the presence of naturally occurring bacteria suggested that artificially inoculated (103 cfu/ml) cells are killed after 3 days, 12 days and 14 days of incubation at 37°C, 8-10°C and 2-4°C respectively.

Airborne Microorganisms in a Pork Processing Establishment

Airborne microorganisms were enumerated in the various processing rooms of a commercial pork slaughter and further processing plant, every other month for a year. The room where sausage emulsions were prepared had higher airborne aerobic bacteria and yeast-mold counts than the other rooms sampled. The mean log aerobic bacteria counts per 0.028 m3 across months were 1.83, 1.83, 1.82, 1.71, 1.93, 2.48, 2.08, 1.62, and 0.95 for the evisceration, offal, carcass cooler, carcass breaking, curing cellar, sausage emulsion preparation, sausage stuffing, sausage packaging, and sliced meat packaging rooms, respectively. The mean log yeast-mold counts per 0.028 m3 for the same rooms were 0.90. 0.88, 0.32, 1.06, 1.11, 1.25, 1.03, 1.01, and 0.97, respectively. Coliform counts did not exceed 5 per 0.028 m3 in any of the samplings and usually were totally absent from the sampled air except in the sausage stuffing and the offal rooms. The mean log aerobic counts per 0.028 m3 for all sampling locations combined were 1.86, 1.78, 1.78, 1.14, 1.84, and 1.93 for February, April, June, August, October, and December, respectively. The lowest count was during the August sampling, and may represent more outside air being introduced into the plant. The mean log yeast-mold counts per 0.028 m3 for the same months were 0.84, 0.53, 1.12, 0.91, 1.04, and 1.03, respectively. The mean temperatures (°C) of the processing rooms referred to above, across months, were 19.5 ± 3.3; 19.4 ± 4.1; 2.4 ± 1.4; 11.0 ± 2.5; 7.0 ± 1.2; 10.0 ± 2.1; 9.3 ± 1.8; 9.6 ± 1.1; and 10.6 ± 0.8, respectively. Different (P<0.05) temperatures within processing rooms among months were noted for the carcass cooler, curing cellar, sausage stuffing, sausage packaging, and sliced meat packaging rooms. These data provide baseline data for the airborne microorganisms in the various rooms in a pork processing establishment.