Sustainable development in the production of healthy vegetable snacks preserved by freeze-drying

The principles of sustainable development in the food industry include general access to food that is safe, affordable and nutrient-rich, and aims to minimize energy consumption, avoid waste and loss of food ingredients throughout the supply chain, and reuse them if possible [1]. Waste of the fruit and vegetable industry is a significant environmental problem. Particularly noteworthy are vegetables, which were rejected in the production process due to unacceptable color, shape or mechanical damage. Most of this type of waste is characterized by high nutritional value, which is worth using when designing new products. An unconventional solution is to obtain vegetable gels that after freeze-drying may become one of the meals or supplement the meal taking the form of a bar [2, 3]. The aim of this work was to develop a three-layer freeze-dried vegetable snacks in the form of bar based on unused during proper production of frozen vegetables. Presented research are the stage of the project BIOSTRATEG 3/343817/17/NCBR/2018 “Development of healthy food production technologies taking into consideration nutritious food waste management and carbon footprint calculation methodology”. Sodium alginate, and a mixture of xanthan gum and locust bean gum were used for the formulation of vegetable gels with carrot, potato, cauliflower, corn, broccoli, green and yellow bean, pepper, chives, dill. Vegetable gels were frozen (–40 °C/2) and freeze-dried (30 °C/63 Pa/72 h). The physical properties of freeze–dried bars included determination of: dry matter content, porosity, shrinkage and compression force. The studies showed that obtaining freeze-dried vegetable snacks based on frozen vegetables not used during the proper production of frozen foods is possible and seems to be very promising considering the growing public awareness of healthy eating. It was shown that more important for physical properties of freeze-dried vegetable gels was hydrocolloid type than vegetables type. Snacks with a mixture of hydrocolloids contained more dry matter content, regardless of the proportion of individual vegetables compared to their counterparts with sodium alginate. The shrinkage of snacks with alginate was significantly larger. The porosity of the lyophilized gels was on the level of 89.06 to 91.82%. Snacks with sodium alginate had a larger number of fine pores, which resulted in a higher porosity and higher compression force when compared to samples with a hydrocolloid mixture.