No abstract

Waste management is still one of the leading global challenges in the 21st century. From the European Union’s point of view, the Waste Framework Directive obliges businesses and households to recycle at least 55% of their municipal waste by 2025 and to reach 65% in 2035. Hence there is a great need to seek new solutions for the reuse of various waste materials. One of the most widely used wastes is their utilization as fillers or reinforcements in the metal- or polymer-based composites. The reuse of wastes for the production of tribological materials gives not only environmental benefits related to the transformation of waste into raw materials but also may improve the mechanical and tribological properties of such materials. Moreover, the use of waste reduces the production costs resulting from the lower price of filler materials and longer service life of developed products. The purpose of the current review is, therefore, aimed at the evaluation of the reuse of agricultural, industrial and postconsumer wastes as reinforcements in the composites used for tribological applications. The tribological performance (wear rate, coefficient of friction) of both monolithic and hybrid composites reinforced with waste materials was a particular subject of interest in this review.

In this study, physicochemical changes occurring in the fruiting bodies of Agaricus bisporus champignons, subjected to mechanical vibrations under model conditions and a 4-day storage (shelf-life), were analysed. The experiment was conducted in two versions (applying vibrations for 3 and 6 h, at the frequencies of 46 Hz and 28 Hz). As part of physicochemical analyses, such parameters as pH, extract, dry mass, colour parameters and colour difference ∆E, polyphenol content and antioxidant activity were determined. The values of the examined physicochemical parameters changed depending on the applied frequencies and vibration time during transport under model conditions, as well as a result of short-term storage (shelf-life). The greatest total colour difference ΔE occurred in the sample subjected to vibrations for 6 h, followed by a 4-day storage. The changes in pH value, dry matter content and refractometric extract were relatively more significant in the samples subjected to 46 Hz vibrations than to those subjected to 28 Hz. The content of polyphenols and the antioxidative activity of mushrooms subjected to vibrations was higher than in the sample stored but not subjected to vibrations.

The study assessed the changes in the quality and physical and chemical parameters of apples of four cultivars (‘Gala’, ‘Idared’, ‘Topaz’, ‘Red Prince’) subjected to mechanical vibration during transport under model conditions and after storage (shelf-life). Quality changes in apples were evaluated based on skin and flesh colour, total soluble solids, dry matter, firmness, titratable acidity, pH value, total polyphenol content, and antioxidant capacity. The vibration applied at a frequency of 28 Hz caused changes in the above parameters, which were visible also after storage and depended on the cultivar, but often did not show any clear trend or direction or were not statistically significant. The values of the total colour difference factor ΔE showed considerable variations in the skin colour but only small variations in the flesh colour of individual cultivars. Vibration resulted in a decrease in firmness. Variations in dry matter, total soluble solids, pH, and titratable acidity were small, often insignificant. Mechanical vibration and storage led to an increase in the polyphenol content and antioxidant capacity of all studied cultivars. The greatest stability of quality parameters, relatively high content of bioactive compounds, and antioxidant capacity were observed for ‘Red Prince’. The lowest quality parameters were noted for ‘Gala’. The analysed cultivars continued to show a high level of antioxidant capacity after treatment, which allows the conclusion that they remain a good source of bioactive compounds after transport and short-term storage.

Many organisations consider environmentally friendly activities, including the reduction of their carbon footprint, to be a significant aspect of their operation. In this study, a mathematical model was used to calculate the carbon footprint of food products at different stages of internal transport, using data on internal transport energy consumption. It was shown that for most products, the highest carbon footprint was related to the raw material transport stage from the loading/unloading point to the workstations on the production line. Broccoli showed the highest carbon footprint for internal transport per tonne of raw material. The study proposes methods of reducing the internal transport-related carbon footprint, which involves reorganising the distribution of goods in the warehouse and using nutritionally valuable vegetable waste in the production of food products.