Effects of gaseous ozone treatment on the mite pest control and qualitative properties during ripening storage of pecorino cheese

BACKGROUND

Ripened cheeses, such as pecorino, are susceptible to mites and molds contamination on the crust area that must be removed before the product can be marketed. This study investigates the effectiveness of gaseous ozone treatment in the control of microbiological and mite growth without negatively affecting product quality.

RESULTS

Cheese samples were treated with gaseous ozone at 200 and 300 ppb for 8 h per day (overnight) for 150 days in storage rooms under controlled conditions (12 °C and 85% relative humidity). The results showed that ozone at 200 ppb limits the growth of mites starting from 25 days of storage and significantly reduced bacteria, molds, and yeasts counts starting from 75 days of storage. Concerning the physicochemical and qualitative parameters evaluated during ripening (weight loss, moisture content, dry weight, ash, fat, protein, total nitrogen, color, non-destructive firmness), no significant differences were shown between the control samples and ozone treatment at 200 ppb. Sensory analysis (consumer test) also showed no specific defects with the ozone-treated samples. It was observed that the ozone treatment at 300 ppb had limited microbiological growth and no alteration of sensory aspects but did not have the same positive impact on some aspects of overall quality, compared with ozone treatment at 200 ppb.

CONCLUSION

The use of gaseous ozone treatments during ripening of pecorino cheese can potentially offer an excellent solution for the control of mite growth, while preserving the quality and sensory characteristics of the product. For this reason, this technique could be very useful for commercial purposes. © 2022 Society of Chemical Industry.

Critically Appraised Topic on Adverse Food Reactions of Companion Animals (8): Storage Mites in Commercial Pet foods

Background

Dogs with year-round atopic dermatitis are often sensitized to Dermatophagoides house dust mites (HDM). Storage mites (SM) are known to grow on cereal-rich foods. Tyrophagus SM can exacerbate clinical signs of allergy in laboratory dogs sensitized to HDM. Consequently, atopic dogs with high-levels of HDM-specific IgE are likely to have a flare of signs after eating a food contaminated with SM; the development of such flares would lead to a false positive diagnosis of food allergy. Herein, we reviewed the published evidence about the growth of SM on commercial dry pet foods.

Results

We searched two databases on January 25, 2019 for articles providing original information on the growth of SM on commercial dog foods. We found ten articles, five reporting results of laboratory experiments and five from field studies. Storage mites, especially Tyrophagus putrescentiae, can multiply on protein- and fat-rich dog foods. The population growth is higher when the initial mite density is high and when kibbles are crushed. When storage conditions lead to the overgrowth of molds on the kibbles, the mite proliferation is higher. Storage mites do not bore holes in food packages but invade bags via defective seals. In the field, SM contamination usually is undetectable in newly-opened commercial dog foods, and, if present, their number is low. When newly-purchased bags are stored in temperate conditions indoors, little overgrowth—if any—of SM occurs. However, when kept in environmental conditions with higher temperature and humidity, Tyrophagus mites will enter and proliferate in sealed food packages.

Conclusions

Commercial dry pet foods should be kept indoors and sealed to decrease the risk of contamination with SM. When performing dietary restriction (elimination) and provocation trials for the diagnosis of food allergies in dogs, it seems preferable to choose newly-purchased bags—of both original and testing diets—to reduce the probability of their contamination with SM, especially Tyrophagus putrescentiae. In case of doubt about the presence of SM in any of these foods, one should perform food challenges with single home-cooked ingredients. Storage mite contamination might lead to an erroneous diagnosis of food allergy in HDM-sensitized dogs.

Mite species identification in the production of allergenic extracts for clinical use and in environmental samples by ribosomal DNA amplification

The identification of allergy-causing mites is conventionally based on morphological characters. However, molecular taxonomy using ribosomal DNA (rDNA) may be particularly useful in the analysis of mite cultures and purified mite fractions in the production of allergenic extracts. Full-length internal transcribed spacers (ITS1 and ITS2) were obtained from Dermatophagoides farinae, Dermatophagoides pteronyssinus, Dermatophagoides microceras and Euroglyphus maynei (Astigmata: Pyroglyphidae), Glycyphagus domesticus and Lepidoglyphus destructor (Astigmata: Glycyphagidae), Tyrophagus fanetzhangorum, Tyrophagus putrescentiae, Tyrophagus longior, Tyrophagus neiswanderi, Acarus farris and Acarus siro (Astigmata: Acaridae), and Blomia tropicalis (Astigmata: Echymopodidae), using mite-specific primers. Polymerase chain reaction (PCR) products were digested with HpaII and RsaI restriction enzymes in order to produce species-specific PCR restricted fragment length polymorphism (RFLP) profiles. A semi-nested re-amplification step was introduced before the RFLP in order to apply the method to environmental samples. Results demonstrate that rDNA sequences can be used for the unambiguous identification of mite species. The PCR-RFLP system allows the identification of species in purified mite fractions when the availability of intact adult mite bodies for morphological identification is limited. This reliable and straightforward PCR-RFLP system and the rDNA sequences obtained can be of use in the identification of allergy-causing mite species.