Efficacy of Liquid Smoke to Mitigate Infestations of the Storage Mite, Tyrophagus putrescentiae, in a Model Semi-Moist Pet Food

SIMPLE SUMMARY: Pests such as mites have been contaminating food products, including pet food, over the years. Mite-infested pet food, apart from causing allergies in pet animals and degrading food quality, can also cause illnesses like asthma in humans as they are often handled by pet owners and children at home. In this study, we evaluated liquid smoke as a natural and clean label additive in semi-moist pet food to protect against mite infestation. Our results indicated that while liquid smoke did not kill or inhibit the mite growth, some liquid smoke fractions provided a repellency effect to retard mite infestation in semi-moist pet food. ABSTRACT: The storage mite Tyrophagus putrescentiae infests a wide range of food products including pet food. Control of this mite depends on chemical methods such as fumigation and spraying with insecticides. Methyl bromide was used as a fumigant for high-value stored products, especially to control mite infestation in dry-cured hams and cheeses, but it is now banned for most uses in many countries because of its atmospheric ozone-depleting effects. Effective alternatives to methyl bromide are needed to develop integrated pest management programs for this pest. Liquid smoke is a naturally derived flavoring and preservative with known antimicrobial properties. The objective of this study was to investigate the efficacy of liquid smoke preparations, with varying phenol and carbonyl concentrations and pH, on the survivability and orientation behavior of T. putrescentiae in a model semi-moist pet food. The mite survivability assays using liquid smoke-treated and untreated semi-moist pet food samples indicated that there was no difference among treatments (p > 0.05) for mite infestation and survival. Two-choice behavioral assays using semi-moist pet food cubes dipped in varying concentrations (0%, 0.3%, 1%, 5%, 10%, 25%, 50%, or 100% v/v) of liquid smoke preparations found that some of the liquid smoke preparations containing medium to high carbonyl content repelled the mites. In conclusion, liquid smoke did not kill or inhibit the mite population growth in semi-moist pet food. However, some liquid smoke fractions containing medium to high carbonyl content were repellent to mites and may retard mite infestation in stored semi-moist foods.