SILKWORM (BOMBYX MORI) PUPAE AS A POTENTIAL NOVEL FOOD

Sericulture is an economic agricultural activity practised in various regions of Europe. Italy has a long tradition of silkworm rearing: in the past, it was Europe's leading silk producer and despite the decline in activity due to economic and environmental difficulties, silkworm rearing is still practised in the country. Among the main obstacles to the resumption of the activity is the difficulty in creating a profitable supply chain that would allow the farmer a sufficient profit margin. One of the possible solutions lies in finding new uses that give greater added value to silk and all the by-products of the supply chain. With this aim in mind, this thesis aims to explore the possibilities of reusing the silkworm chrysalis, a by-product that is poorly valorised at present, by evaluating and studying its use in the food sector. The first chapter is an introduction to the silkworm, explaining its history, the importance of the insect, traditional and innovative uses. Finally, the factors to be taken into account, within the European scenario, to develop a food product from the chrysalis are analysed. Chapter II presents the objectives of this work. The following chapters present the results of the literature search which were obtained with the aim of gathering the data necessary for the presentation of a novel food dossier, i.e. a document gathering information on the safety and composition of a potential novel food. The ‘systematic review’ methodology is applied to obtain reliable and comprehensive data on the chemical composition of the chrysalis in terms of macronutrients (Chapter III) and on data on all aspects of the safety of chrysalis as a food (Chapter IV). Subsequently, Chapter V focuses on evaluating the chemical and microbiological safety of silkworms reared in the Veneto region, also testing the relative extraction products. The sixth chapter, on the other hand, evaluates how the microbiological load varies according to the different farms and phases of the silkworm life cycle and examines how the current cocoon drying process impacts the microbial load of the chrysalis. Moreover, in anticipation of the future use of the chrysalis as a food, in chapter seven, various alternative technological processes applied to kill and dry the chrysalis are studied, evaluating how they affect the microbiological load and oxidative state of the final product. Once the best technological process has been identified, the shelf-life is evaluated and analyses are carried out to characterise the food, for the preparation of the ‘novel food’ dossier. In the eighth chapter, the catalogue of silkworm breeds conserved at the Laboratory of Sericulture of Padua is presented, reporting the morphological descriptors used. Finally, the ninth chapter contains the final conclusions of this thesis work.