Effect of high pressure processing on the inactivation of spoilage microorganisms and L. innocua and E. coli cells inoculated in a mixed fruit and vegetable smoothie

FERNÁNDEZ MARÍA VERÓNICA; VAUDAGNA, SERGIO; AGÜERO MARÍA VICTORIA; JAGUS ROSA JUANA; DENOYA, GABRIELA

Sorrento

Workshop; International Nonthermal Processing Workshop and Short Course; 2018

Universidad de Sorrento

The availability of sugar, nutrients and high aw make fruit and vegetable (F&V)beverages susceptible to microbial growth, one of the main causes of spoilage.Additionally, reports indicate that pathogenic species like Listeria monocytogenes and Escherichia coli, among others, can survive in these products during long periods of storage. High hydrostatic pressure (HHP) technology is proposed as an alternative processing method able to improve microbiological stability, while preserving sensory and nutritional characteristics of food products.The aim of this study was to evaluate the microbial stability of F&V smoothies treated with HHP during 28 days of storage at 5ºC. Additionally, the effectiveness against a Listeria innocua and Escherichia coli contamination was determined during 12 days of storage at abuse temperature.The ingredients (orange juice 59%, apples 15%,carrots 15%, beet leaves 6% and beet stems 5%) were washed, peeled, chopped and blended in a homogenizer. The smoothie was packed into polyethylene terephthalate bottles (100 mL) and then processed with HHP (630 MPa / 6 min). Mesophilic aerobic bacteria, Enterobacteriaceae and molds and yeasts counts were determined. In order to evaluate the treatment effectiveness against a contamination with microorganisms of interest,smoothies were inoculated with Listeria innocua and Escherichia coli simulating a contamination in stages prior to HHP treatment.Treatment of the F&V smoothies with HHP reduced native microbiota to values below detection limit (DL= 1 log CFU/g) until the end of the storage, eliminating one of the main causes of deterioration of these products.Moreover, the HHP technology, allowed control a contamination of 6 log CFU/g of E. coli and L. innocua, for at least 12 day sat 15ºC.These results indicate that the HHP treatment applied is effective not only to improve microbial stability of the products but also to ensure their safety when a contamination occurs.