Quality Properties and Headspace Volatiles of Hot Air-Dried Strawberries.

Strawberry is one of the most important soft fruit in food industry. With its flavor and antioxidant content, it is widely used mainly in confectionery and beverage industry. Strawberries are perishable and this limits their usage in foods. For that reason, drying is one of the solutions to make them durable. The aim of this study is to analyze certain quality parameters and headspace volatiles of hot air-dried 'Florida Fortuna' and 'Osmanli' strawberries (Fragaria xananassa) at 50, 60 and 70°C. The results showed that drying the strawberry samples at high drying temperature caused a decrease in acidity and bulk density and a deterioration in ascorbic acid content. However, total phenolic contents and total color difference values of both of strawberry samples increased with drying process. A total of 24 headspace volatiles were detected in dried strawberries. The most abundant volatiles were dimethyl sulfide, acetic acid and acetone. The highest number of compound groups were aldehydes, acids, esters and sugar degradation products, respectively. The highest retention of fresh strawberry volatiles and minimum formation of sugar degradation products were obtained by drying at low temperature.

Identification of predominant aroma components of raw, dry roasted and oil roasted almonds.

Volatile components of raw, dry roasted and oil roasted almonds were isolated by solvent extraction/solvent-assisted flavor evaporation and predominant aroma compounds identified by gas chromatography-olfactometry (GCO) and aroma extract dilutions analysis (AEDA). Selected odorants were quantitated by GC-mass spectrometry and odor-activity values (OAVs) determined. Results of AEDA indicated that 1-octen-3-one and acetic acid were important aroma compounds in raw almonds. Those predominant in dry roasted almonds were methional, 2- and 3-methylbutanal, 2-acetyl-1-pyrroline and 2,3-pentanedione; whereas, in oil roasted almonds 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2,3-pentanedione, methional and 2-acetyl-1-pyrroline were the predominant aroma compounds. Overall, oil roasted almonds contained a greater number and higher abundance of aroma compounds than either raw or dry roasted almonds. The results of this study demonstrate the importance of lipid-derived volatile compounds in raw almond aroma. Meanwhile, in dry and oil roasted almonds, the predominant aroma compounds were derived via the Maillard reaction, lipid degradation/oxidation and sugar degradation.

Detection and enumeration of four foodborne pathogens in raw commingled silo milk in the United States.

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.