The polyphenol content of cocoa beans and the products derived from them, depend on the regions in which they are grown and the processes to which they are subjected, especially temperature. The aim of the study was to compare the total content of polyphenols and antioxidant activity of chocolates obtained from roasted and unroasted cocoa beans. The chocolates produced from each of the six types of unroasted beans and each of the five types of roasted beans were investigated. The seeds came from Ghana, Venezuela, the Dominican Republic, Colombia and Ecuador. The highest total polyphenol content was determined in cocoa beans originating from Colombia and in the chocolates obtained from them. A higher content of total polyphenols was found in unroasted cocoa beans, which indicates the influence this process had on the studied size. The ability to scavenge free DPPH radicals was at a high level in both the beans and the chocolates produced from them, irrespective of the region where the raw material was grown. A positive correlation between the total polyphenol content and the ability to scavenge free radicals was found.

This study aimed to determine the effect of edible coatings based on whey protein isolate and essential oils (lemon and lemongrass) on the colour, hardness, polyphenols and flavonoids content, structure, and sensory attributes of fresh-cut pears during storage at 4 °C. The optical and barrier properties of the edible films were also determined. Analysed films showed good transparency (Lightness 86.6–95.0) and excellent oxygen and carbon dioxide permeability, which were reduced due to the presence of lemon and lemongrass essential oils. Pears were coated by immersion in a solution containing 8% of whey protein isolate and the addition of lemon oil at 1.0% or lemongrass essential oil at 0.5%. Coating caused a reduction in colour changes, loss in hardness, polyphenols and flavonoids. The study showed that the highest efficiency was demonstrated by the whey protein isolate coatings without the addition of essential oils by preserving the colour and firmness of fresh-cut pears. For these samples, the highest sensory acceptability was also achieved.

The purpose of this study was to determine the possibility of using a chokeberry juice concentrate as a component of osmotic solution and convection-microwave-vacuum drying applying to obtain dried pro-health-promoting strawberries. The research material was Honeoye strawberries, which were dehydrated in sucrose and sucrose with chokeberry juice concentrate addition, and then subjected to microwave-convection-vacuum or freeze-drying. Analyses were conducted to determine the influence of the applied processes on vitamin C content, total polyphenols, antioxidant activity, and sensory properties in dried fruit. Study results confirmed the possibility of using a chokeberry juice concentrate as a component of the osmotic solution, especially with regard to polyphenolics content and antioxidant activity. In addition, convection-microwave-vacuum drying was shown to be a promising technology for the production of dried strawberries, with high pro-health potential and acceptable sensory qualities.

Osmotic dehydration (OD) of apples caused a reduction of normalized water content (NWC) and an increase of normalized solids gain (NSG), independently of the kind of osmotic solution. The use of 22°Brix osmotic solutions with the addition of fruit concentrates or bilberry extract resulted in only slight reduction in the NWC in the samples, i.e. by about 15 and 20%, respectively after 6 and 24 h, against a value up to 80% in case of 65°Brix use. Similarly, larger NSG was achieved at higher solution concentrations, but the differences were smaller. In the case of the use of 80% bilberry press cake extract the NSG was very low but NWC was relatively high. Such a low concentration of slightly concentrated fruit juices is not effective for dehydration of apples, but it may be sufficient to enrich the fruit with the desired colorants. This higher concentration of osmotic solution and a larger addition, especially of the concentrate of chokeberry juice, significantly affected the color changes of dehydrated apples. The apple dehydrated in mixture of 65°Brix sucrose and 15% chokeberry juice concentrate solution exhibited the highest sensory parameters. The addition of berry fruit juices and extract was able to improve the apple sensory quality after 24 h OD in comparison with sucrose solution. Ethanol extract was a good osmotic agent, but not accepted due to taste and overall quality. However, the addition of the extract can be successfully used in conjunction with a sugar solution.

This paper presents the influence of blanching, ultrasonic processing and freezing conditions on selected physical properties of freeze-dried red beet, i.e., water activity, structure, porosity and shrinkage. Red beets subjected to a selected pre-treatment using its various parameters were frozen by three methods and then freeze-dried. Ultrasound reduced the water activity of samples. Blanching in water reduced shrinkage and improved porosity. In addition to the type of pre-treatment applied, the quality was also affected by freezing conditions before drying. Combined freezing resulted in the highest shrinkage and the lowest porosity and water activity. Slowly frozen samples were characterized by the best porosity.

The aim of the current research was to evaluate the effect of pre-treatment and drying methods on the properties of dried carrots. Carrots were blanched (B) (1 or 3 min) or osmotic dehydrated (OD) (15 or 30 min) and dried by either convection (CD), microwave-convection (MW-CD), microwave-vacuum (MVD), or freeze-drying (FD). FD carrots showed the highest dry matter content (93.6–95.8%) and the lowest water activity (0.24–0.38). MVD carrots had lower dry matter content (79.5–95.8%) and two times more water activity (0.447–0.637) than FD. The highest color difference (∆E) in relation to raw material was noted in MVD samples (22–35) and the smallest in CD and FD (7–18), mainly due to the increase in brightness of the dried carrot. In general dried MCD carrot samples were characterized by the highest max force (hardness) (21.6–42.5 N; on average 34.7 N) in the breaking test and the lowest hardness was observed in the CD (10.8 N) ones. Pre-treatment and drying caused a significant decrease in the content of carotenoids (2.0–2.7 times) and chlorophyll (2.7–4.5 times) compared to the fresh carrot but a retention or increase in the total content of phenolics and antioxidant activity, especially in microwave-vacuum-dried carrots with an increase of even 2.7–2.9 times compared to raw material. High phenolic content (195.6–277.4 mg GA/100 g d.m.) was found in pre-osmotic dehydrated samples, and lower phenolic content was found in blanched samples (110.7–189.6 mg GA/100 g d.m.). Significantly, the highest average antioxidant activity was found in microwave-vacuum-dried samples (228.9 µmol Trolox/100 g d.m.). The results of this study indicate that microwave-vacuum-drying as an alternative to freeze-drying, including in combination with thermal or osmotic treatment, is very promising for the production of dried carrot snacks.