Retention of short chain fatty acids under drying and storage conditions

Cheese whey permeate was used as a substrate for the fermentation of Propionibacterium freudenreichi PS1 for the production of short chain fatty acids, components of the bio-aroma of Swiss cheese. The liquid bio-aroma was encapsulated by spray drying under different conditions of air inlet temperature and feed rate. A study was carried out on the stability of the bio-aroma during storage in laminated packages at 30 °C for 96 days using the product showing the greatest retention of acetic and propionic acids. The results showed that the best drying conditions were an air entrance temperature of 180 °C and a feed rate of 24 g/min resulting in particles with a smooth surface and few invaginations and micro-fissures. However, 72% of the acetic acid and 80% of the propionic acid were lost during storage showing that the wall material used was inadequate to guarantee product stability.

Use of the polymerase chain reaction for detection of Fusarium graminearum in bulgur wheat

The detection of mycotoxigenic fungi in foodstuff is important because their presence may indicate the possible associated mycotoxin contamination. Fusarium graminearum is a wheat pathogen and a producer of micotoxins. The polymerase chain reaction (PCR) has been employed for the specific identification of F. graminearum. However, this methodology has not been commonly used for detection of F. graminearum in food. Thus, the objective of the present study was to develop a molecular methodology to detect F. graminearum in commercial samples of bulgur wheat. Two methods were tested. In the first method, a sample of this cereal was contaminated with F. graminearum mycelia. The genomic DNA was extracted from this mixture and used in a F. graminearum specific PCR reaction. The F. graminearum species was detected only in samples that were heavily contaminated. In the second method, samples of bulgur wheat were inoculated on a solid medium, and isolates having F. graminearum culture characteristics were obtained. The DNA extracted from these isolates was tested in F. graminearum specific PCR reactions. An isolate obtained had its trichothecene genotype identified by PCR. The established methodology could be used in surveys of food contamination with F. graminearum.