The Quality of Freeze-Dried and Rehydrated Blueberries Depending on their Size and Preparation for Freeze-Drying

Effect on Phytochemical Content and Microbial Contamination of Actinidia Fruit after Shock Cooling and Storage

Mini kiwi fruits are tasty and contain valuable nutrients - vitamin, micro end macroelements and polyphenols. The tested cultivars (Sientiabrskaja, Geneva, Issai, Ken’s Red) belong to two species of Actinidia (A. arguta and A. kolomikta), which tolerate well the conditions of a temperate climate with negative temperatures in winter. The effect of postharvest shock cooling on fruit quality was investigated after 6 weeks of storage in CA and then after 5 days of shelf life. Shock cooling of fruit after harvest reduced adverse changes in fruit quality after storage in CA cold storage and shelf life. They were firmer, more puncture resistant, and retained more L-ascorbic acid and polyphenols. After 6 weeks of cold storage in CA, eight types of fungi and molds were found that caused the mycotoxins patulin, deoxynivalenol, and zearalenone were found in the fruit of all cultivars. Fruits of the Ken’s Red cultivar were the most firm and puncture resistant, the darkest, and contained the most anthocyanins and the least L-ascorbic acid. In contrast, fruits of the cultivar Sientaibrskaja were the least suitable for storage and transport.

Chemical and Enzymatic Changes of Different Soils during Their Acidification to Adapt Them to the Cultivation of Highbush Blueberry

Although there has been an increase in the cultivation of highbush blueberry (Vaccinium corymbosum L.) worldwide for several years now, the availability of suitable soils for this species remains a problem. Highbush blueberry is a plant that requires acidic soils (pH 3.8–5.5), which are well aerated and have a stable level of groundwater and high humus content. In the present study, substances such as urea phosphate fertilizer, sulfur, sulfuric acid, and phosphogypsum were used to acidify three soils: peat, loamy sand, and loamy silt. The study aimed to lower the pH of the tested soils and optimize this parameter to cultivate highbush blueberry. The resulting changes in pH, content of macro- and micro-elements, and enzymatic activity were evaluated. Acidifying substances mitigated peat and loamy sand’s reaction to highbush blueberry requirements, while the reaction of loamy silt was changed only slightly, which made this soil unsuitable for plant cultivation. Sulfur dust acidified the examined soils rapidly and to the highest degree, followed by urea phosphate and phosphogypsum, while the weakest acidification was achieved with sulfuric acid solutions. The salt concentration of the soil was increased the most by the highest dose of phosphogypsum, which indicated that it could not be used to acidify soil for the cultivation of highbush blueberry. Among the acidifying substances, only urea phosphate showed a stimulating effect on the soils’ enzymatic activity, whereas others did not significantly affect or decrease this parameter.

Changes in the Quality of Old Apple Cultivars After Freeze-Drying

There are several thousand different cultivars of apple trees but only a limited number are cultivated on an industrial scale. Old cultivars can be useful, for example, in the processing industry due to their different composition. In many cases, they have higher organic acid content. The content of mineral components, colour, and polyphenols in the fruit of 7 old apple tree cultivars, growing in the Wolinski National Park, was studied. The changes that occurred in the fruit after freeze-drying were also evaluated. The trees from which the fruit was picked for analysis, despite the lack of chemical protection, were fruiting and the apples had only a few symptoms of damage caused by pests or diseases. The fruit was characterised by a high soluble solids content (14.4-16.4%), in which sugars and especially fructose dominated. The number of organic acids varied greatly and ranged from 0.27 (Oberlander Himbeerapfel) g to 1.07 g/100 g (Winter Goldparmane). The content of polyphenols in fresh apples ranged from 186 mg (Horneburger Pfannkuchenapfel) to 354 mg/100 g (Winter Goldparmane) and increased after freeze-drying from 666 mg (Weisser Winterkalvill) to 1486 mg/100 g (Winter Goldparmane). The dominant group of polyphenolic compounds was phenolic acid. The freeze-drying process caused unfavourable changes in the colour of the pulp. The fruits of Oberlander Himbeerapfel cultivar were most susceptible to these changes. However, the least darkened fruit of Horneburger Pfannkuchenapfel.