Antimicrobial packaging design : Exploring the potential of allyl isothiocyanate release from mustard seeds

Food spoilage is a major challenge in extending the food shelf life and for the consumer to consume fresh and nutritious product demands. Antimicrobial packaging system is designed to inhibit the spoilage bacteria growing in food products. Allyl isothiocyanate (AITC) is acknowledged as a volatile and strong antimicrobial compound that can inhibit the growth of a variety of microorganisms in food products. Mustard seeds containing a high content of sinigrin, which is the precursor of AITC, can be used as an antimicrobial carrier in antimicrobial packaging. This thesis aimed to explore the potential of allyl isothiocyanate release from mustard seeds to design an antimicrobial packaging. The factors influencing the released AITC concentration and its efficacy on microbial growth in a packaging system were investigated. The AITC concentrations were measured in each phase of the packaging system (antimicrobial source, headspace and (model) food). Mass transfer and reactions occurring inside the package were described by a kinetic model containing a set of combined mathematical equations to understand the mechanism of formation, release, absorption, and degradation of AITC. The antimicrobial effects of AITC on the growth of spoilage bacteria in a food medium and/or real food were analyzed to understand the effectiveness of the antimicrobial package in microbial inhibition and the extension of the shelf life of foodsResults show lower fat content in ground mustard seeds and thinner thickness of mustard-incorporating film release higher AITC into packaging headspace. AITC in the seeds, packaging polymer, headspace volume and food components influenced the partitioning rate of AITC into the foods. An increase in the protein content of the food caused a slower AITC penetration into the food matrix, but the complex between proteins and AITC stabilized AITC in the food matrix. Furthermore, a higher temperature resulted in faster AITC absorption by the food matrix and faster degradation in the packaging system. Higher concentration and better stability of AITC in the headspace inhibit the spoilage bacteria in medium and foods in a prolonged time without influencing food sensory attributes. Multiresponse kinetic modelling has been established to describe the mechanism of mass transfer and reaction of AITC in the packaging system.The design of antimicrobial packaging using in-situ formation to control the release of antimicrobial compounds into the headspace gives new opportunities to effectively inhibit microbial growth and prolong shelf life. The study gives an insight into a natural antimicrobial source as sustainable and low-cost concepts to be applied in the food packaging system. The system that effectively inhibits the spoilage bacteria can reduce global food waste and fulfil consumer demands on fresh foods.&nbsp