Recent advances in plant essential oils and extracts: Delivery systems and potential uses as preservatives and antioxidants in cheese

Background Cheese is one of the most widely consumed dairy products worldwide with high commercial value. As cheese consumption and distribution have increased over the years, the cheese industry had to address the issues of safety and preservation of cheese products as well as cheese whey utilization-management. Although not frequently used, preservatives are added in some types of cheese that are naturally susceptible to spoilage (e.g. fresh cheeses), in order to extend their shelf-life. However, consumers' increasing awareness regarding health issues have turned their interest towards minimally processed food and products with ‘clean labels’. In this respect, artificial additives tend to be replaced by natural ones, such as essential oils and extracts from different plants. These natural products exhibit a remarkable antimicrobial and antioxidant activity and, due to their properties, their use as alternative food additives have increased in recent years. Scope & approach Application of essential oils and extracts as preservatives and antioxidants in different types of cheese has been widely studied through the last years. However, despite the promising results for the antimicrobial and antioxidant activities of these natural constituents, their use is still limited in the cheese industry, as they negatively affect the physicochemical and sensory characteristics of the end products. Αn alternative approach to addressing such quality defects, could be encapsulation of essential oils and extracts before their application in cheese products. As there is growing interest in this field, the aim of this paper was to review the latest findings on whether encapsulated essential oils and extracts can act as effective preservatives and/or antioxidants in cheese products. Key findings and conclusions Overall, the performance of essential oils and extracts as preservatives and antioxidants in cheeses is enhanced through encapsulation. In this context, several delivery systems have been examined, e.g. edible films/coatings, being the most commonly used, followed by nanofibers or microcapsules. Both antimicrobial and antioxidant activities are prolonged, since the bioactive compounds in the encapsulant matrix are protected from oxidation, volatilization and degradation. Additionally, interactions between food matrix components and essential oils/extracts constituents are limited, whereas for the films/coatings incorporating essential oils/extracts there is better control of moisture and mass losses during storage, preventing hardness. Even more important is the maintenance of the desired organoleptic characteristics and other quality attributes of the cheese products, along with a concurrent extension of the shelf-life.