Influence of high-pressure homogenization treatments combined with lysozyme activated packaging on microbiological and technological quality of vegetable smoothie during shelf life

In this study the effect of a high pressure homogenization (HPH) treatment, alone and in combination with a biodegradable polylactic acid (PLA) packaging activated with lysozyme on a smoothie made with apple, carrot and rice beverage was evaluated. In particular, the effects of treatments on the microbiological and quality characteristics of smoothies were assessed during storage at 4 and 10 & DEG;C in climatic chambers at RH of 50 %. Obtained results showed the efficacy of HPH at 100 MPa to reduce the initial cell load of mesophilic and psy-cothrophic aerobic bacteria, lactic acid bacteria, yeasts and aerobic spore-forming bacteria. Moreover, the combination of HPH and lysozyme activated packaging resulted in an increased antimicrobial effect against mesophilic, psychrotrophic and lactic acid bacteria during product storage at 10 & DEG;C. Yeast and spore forming bacteria showed, instead, lower cell loads independently from samples. Samples packed in active packaging, both treated and not, showed a better color retention in terms of lightness and red index, compared to control (C) ones both when stored at 4 and 10 & DEG;C. The HPH treated smoothies, both activated and not, at 4 & DEG;C remained microbiologically stable for more than 20 days. However, the use of active packaging has also allowed to reduce the microbiological proliferation during storage at 4 & DEG;C. Moreover, few differences in color indices were high-lighted between samples stored at 4 & DEG;C. Obtained results indicate that the combination of HPH treatment and active packaging may represent a useful strategy to increase safety and shelf-life of vegetable smoothies.

Automated summary

This study evaluated the effects of HPH treatment and PLA packaging activated with lysozyme on a smoothie made with apple, carrot, and rice beverage. The results showed that HPH treatment effectively reduced the initial cell load of various bacteria and yeast. When combined with lysozyme activated packaging, the antimicrobial effect against bacteria was further increased. The use of active packaging also improved color retention. Overall, the combination of HPH treatment and active packaging could enhance the safety and shelf-life of vegetable smoothies.