The aim of this study was to assess shelf life and nutritional value of apple juice, including the content of bioactive compounds, after pulsed electric field (PEF) treatment, taking into account different number of cycles: 4, 6, 8 (total 200, 300, and 400 pulses, respectively). Determination of vitamin C and polyphenols concentration, antioxidant activity as well as microbiological analysis were conducted immediately after PEF process and after 24, 48 and 72 h of storage. The results showed that PEF did not affect the content of bioactive compounds. PEF-treated juice did not show changes in the amount of vitamin C and total polyphenols during the storage for 72 h under refrigeration. PEF treatment was effective method for inactivation of a wide range of most common food spoilage microorganisms. PEF process can be used as an effective method of food preservation, allowing prolongation of shelf life and protection of nutritional value. This brings new opportunities for obtaining safe, healthy and nutritious food.
The paper presents the results of an evaluation of the quality of eggs from laying hens kept in caged and free range systems using traditional methods and ultra-weak luminescence (USL). It was found that the tested eggs were fresh and were characterized by the required quality, as demonstrated by analysis of the egg white and egg yolk. Eggs from free-range laying hens were characterized by an eight-fold higher emission of photons compared to eggs from caged hens, and they had over three times higher content of natural antioxidants in the form of carotenoids. Most probably, the higher number of photons emitted is associated with a higher content of biologically active substances in the material under study. Photon emission also varies in different ways depending on the specific hen breeding system. Differences in time in the identified maximum values of photon emission result from the composition of individual parts of the egg. Different times in which the emission peaks occurred for free-range eggs and for caged eggs were observed. The application of the USL method in order to confirm its usefulness in the assessment of food quality requires further research.
Staphylococcus aureus is a bacterium which people have been in contact with for thousands of years. Its presence often leads to severe disorders of the respiratory and circulatory systems. The authors of this article present a prototype of a textronic sensor enabling the detection of this bacterium. This sensor was created using a process of physical vacuum deposition on a flexible textile substrate which can be implemented on clothing. With increasing numbers of bacterial colonies, changes in the sensor’s electrical parameters were observed. The sensor’s resistance reduced by 50% and the capacitance more than doubled within the first two days of starting bacterial cultures. Extensive changes in electrical parameters were observed at 100 Hz and 120 Hz of the measurement signal.
In the food industry, the pulsed electric field (PEF) technique is used to support the process of extraction of various substances. The aim of this study was to analyze the effect of a number of PEF pulses applied to peppermint and caraway on both the content of essential oils (EO) and their spectroscopic properties. The examined herb species were placed in a special vessel in the working chamber of the device between two electrodes providing high voltage electric pulses. The pulses were delivered 0, 150, 250, and 350 times per a studied sample of each herb. Essential oils were then obtained by way of hydrodistillation. The infrared spectra for all samples were measured using an FTIR spectrometer in the spectral range of 3700–730 cm−1. The applied electric field of a predetermined number of pulses had no significant effect on the amount of distilled essential oil from caraway fruit, while in the case of peppermint, it caused a slight decrease in relation to the raw material not subjected to PEF exposure. It was found that the analysis of infrared spectra made it possible to compare the quality of the obtained oils with each other and to pre-determine their compositions.
Waste incineration is one of the paths of implementation of the European Union’s strategy aimed at reducing the amount of waste deposited in landfills. Along with the development of methods for processing and recycling various wastes, new waste is generated. One example is waste from polyethylene terephthalate (PET) bottles washed during their recycling. In this paper, physical and chemical properties of such wastes are analyzed in terms of their use in the power industry. This research is part of the search for new sources and new technologies for energy production. The study has taken into account the energy properties of waste intended for combustion (calorific value, water content, chemical composition, volatile substances, combustible and non-flammable content). Thermogravimetric analysis of the material tested indicated that the waste is a good source of energy. It was found that the elemental composition (C, H, N, S, O) of the waste investigated is similar to that for biomass materials, and the calorific value of 13.2 MJ/kg qualifies the waste for combustion, provided that its initial moisture is reduced, for example, for co-combustion in the cement industry. Another possibility is mixing the waste with other kinds of waste to obtain a new fuel with more satisfactory parameters.
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