Effects of Essential Oils and Hydrolates on the Infectivity of Murine Norovirus

Antiviral Activity of Natural Compounds for Food Safety

Gastroenteritis and hepatitis are the most common illnesses resulting from the consumption of food contaminated with human enteric viruses. Several natural compounds have demonstrated antiviral activity against human enteric viruses, such as human norovirus and hepatitis A virus, while little information is available for hepatitis E virus. Many in-vitro studies have evaluated the efficacy of different natural compounds against human enteric viruses or their surrogates. However, only few studies have investigated their antiviral activity in food applications. Among them, green tea extract, grape seed extract and carrageenans have been extensively investigated as antiviral natural compounds to improve food safety. Indeed, these extracts have been studied as sanitizers on food-contact surfaces, in produce washing solutions, as active fractions in antiviral food-packaging materials, and in edible coatings. The most innovative applications of these antiviral natural extracts include the development of coatings to extend the shelf life of berries or their combination with established food technologies for improved processes. This review summarizes existing knowledge in the underexplored field of natural compounds for enhancing the safety of viral-contaminated foods and underscores the research needs to be covered in the near future.

Strategies to improve the postharvest management of flat oyster (Ostrea edulis) from aquaculture using the short-term storage and package in an innovative closed-circuit system

This study aimed to improve postharvest management of flat oysters reared in a longline system in the mid Adriatic Sea, using short-term storage and package in an innovative closed-circuit system. For the trial, 870 oysters were employed, divided into three experimental groups (A, B, and C), N = 270 oysters each group, whereas the remaining 60 oysters were used for the 2 controls. Each group differed in relation to the time spent in the depuration tank and the time of packaging: group A was packed and immediately transferred to the cell; group B was depurated in a tank for 48 h, then packed and transferred to the cell; group C was depurated in a tank for 48 h and then packed, depurated for another 24 h and transferred to a cell. Samples of each group were sampled at different times of permanence in cell (t0) up until 12 days (t12) for biomorphometric, sensorial, nutritional, and microbiological analysis. Although the nutritional and sensorial quality of the oysters was more pronounced in group A, B and C groups also showed good results. In these two groups, thanks to the use of the modern water recirculation system the quality and safety of oysters was improved by reducing the presence of sludge and eliminating fecal contaminants completely than A treatment and seawater control. These results were also confirmed by the tank control, where a more extended depuration period positively influenced the same parameters emphasizing the importance of the adequate depuration processes in oyster production.

In Vivo Evaluation of the Potential of Thyme and Lemon Hydrolates as Processing Aids to Reduce Norovirus Concentration during Oyster Depuration

In this study, we evaluated the use of hydrolates, co-products of essential oil distillation, as processing aids to improve the depuration process of Pacific oysters (Crassostrea gigas) as a post-harvest method aimed at reducing the norovirus (NoV) viral load. Live oysters were kept in water to which hydrolates of Thymus serpyllum and Citrus limon at 1% were added for 24 h. The concentration of NoV was quantified using the ISO 15216-1 quantitative real-time RT-PCR method in the oyster digestive tissue both before and after the treatment. The results showed a significant reduction of 0.2 log in the NoV GII concentration after 24 h of treatment with 1% C. limon hydrolate. Conversely, treatment with T. serpyllum did not appear to reduce the concentration of NoV compared to the control. Additionally, a sensory analysis was conducted through a blind survey comparing untreated and treated oysters. No changes in the sensory and physical characteristics of the oysters were observed, except for a decrease in the marine flavour intensity, which was positively perceived by consumers. These results indicate that the addition of hydrolates of C. limon at 1% during depuration might represent a promising processing aid for enhancing both the safety and acceptability of live oysters.