No abstract

A nationwide survey was conducted to obtain qualitative and quantitative data on bacterial contamination of raw commingled silo milk intended for pasteurization. The levels of total aerobic bacteria, total coliforms, Enterobacteriaceae, Escherichia coli, and Staphylococcus aureus were determined using the TEMPO system. The prevalence rates and levels of presumptive Bacillus cereus, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. were determined in 214 samples. B. cereus was detected in 8.91% of samples, at 3.0 to 93 CFU/ml. E. coli O157:H7 was detected in 3.79 to 9.05% of samples, at <0.0055 to 1.1 CFU/ml, depending on the assay utilized. Salmonella spp. were recovered from 21.96 to 57.94% of samples, at <0.0055 to 60 CFU/ml. L. monocytogenes was detected in 50.00% of samples, at <0.0055 to 30 CFU/ml. The average log-transformed counts of total viable bacteria were slightly lower in samples containing no pathogens. No correlation was observed between the levels of organisms detected with the TEMPO system and the presence or levels of any pathogen except E. coli O157:H7. A higher average log-transformed count of total viable bacteria was observed in samples positive for this organism. The high prevalence rates of target pathogens may be attributed to a variety of factors, including detection methods, sample size, and commingling of the milk in the silo. The effects of commingling likely contributed to the high prevalence rates and low levels of target pathogens because of the inclusion of milk from multiple bulk tanks. The high prevalence rates also may be the result of analysis of larger sample volumes using more sensitive detection methods. These quantitative data could be utilized to perform more accurate risk assessments and to better estimate the appropriate level of protection for dairy products and processing technologies.

This study aimed to dry orange peels using tray drying (TD), vacuum infrared drying (VID), and vacuum microwave drying (VMD) techniques and to investigate the effects of different drying techniques on the drying kinetics, physical, chemical characteristics, and volatile compounds. The VMD raised the drying rate and the effective water diffusivity compared to the TD and the VID. It was detected that the TD, VID, and VMD at 50°C required 300, 106, and 20.67 min, respectively. The VMD showed the highest vitamin C, total phenolic substance, total carotenoid content, whereas the TD indicated the lowest color values. A total of 63 volatile compounds which consist of 16 aldehydes and ketones, 4 esters, 34 terpenes, and 9 other types of compounds were determined in dried orange peels. It was determined that the VID technique caused the least destructing in volatile compounds, whereas the TD technique was the most destructive.Practical ApplicationsDrying is a common preservation method used for the long‐term durability of foods. Drying of orange peel conduces not only to decrease environmental problems but also to provide economic benefits. Dried orange peel is used in herbal teas and food products because it is rich in aromatic flavor and odor components. Orange peel was dried using tray drying, vacuum infrared drying, and vacuum microwave drying. The vacuum microwave drying increased the drying rate and effective water diffusivity to others. The vacuum microwave drying and vacuum infrared drying protected quality characteristics, and volatile compounds of orange peels. This study demonstrated that the waste orange peels could be dried with different drying methods and converted into products with high nutritional components.