Impact of Ultrasound Pretreatment on Juice Yield and Bioactive Content in Juice Produced from Selected Berries Fruit

The aim of the work was to investigate the effect of ultrasound application during juice pressing. The impact on pressing yield and extraction of bioactive compounds during production of juice from strawberry, blackcurrant and raspberry was evaluated. Juice pressing was carried out after four kinds of mash pretreatment. The tested objects were heated to 55 °C, treated by ultrasound, and/or macerated with an enzyme. The obtained juices were analyzed for the content of bioactive compounds and compared to the 'Control' sample, which was the juice pressed without any pretreatment. Although the results presented here do not conclusively show that enzymatic maceration can be completely replaced by the use of ultrasound, in the case of strawberry and raspberry fruit, juice yield after ultrasound treatment increased almost as much as after enzymatic maceration. Additionally, in the case of raspberry fruit, the antioxidant activity of the juice samples was definitely improved when ultrasound was used. The results from this experiment also showed that it is possible to separate the effect of temperature from the effect of mechanical and chemical actions in ultrasound treatment.

Discrimination of tomato seeds belonging to different cultivars using machine learning

This study was aimed at developing the discriminant models for distinguishing the tomato seeds based on texture parameters of the outer surface of seeds calculated from the images (scans) converted to individual color channels R, G, B, L, a, b, X, Y, Z. The seeds of tomatoes ‘Green Zebra’, ‘Ożarowski’, ‘Pineapple’, Sacher F1 and Sandoline F1 were discriminated in pairs. The highest results were observed for models built based on sets of textures selected individually from color channels R, L and X and sets of textures selected from all color channels. In all cases, the tomato seeds ‘Green Zebra’ and ‘Ożarowski’ were discriminated with the highest average accuracy equal to 97% for the Multilayer Perceptron classifier and 96.25% for Random Forest for color channel R, 95.25% (Multilayer Perceptron) and 95% (Random Forest) for color channel L, 93% (Multilayer Perceptron) and 95% (Random Forest) for color channel X, 99.75% (Multilayer Perceptron) and 99.5% (Random Forest) for a set of textures selected from all color channels (R, G, B, L, a, b, X, Y, X). The highest average accuracies for other pairs of cultivars reached 98.25% for ‘Ożarowski’ vs. Sacher F1, 95.75% for ‘Pineapple’ vs. Sandoline F1, 97.5% for ‘Green Zebra’ vs. Sandoline F1, 97.25% for Sacher F1 vs. Sandoline F1 for models built based on textures selected from all color channels. The obtained results may be used in practice for the identification of cultivar of tomato seeds. The developed models allow to distinguish the tomato seed cultivars in an objective and fast way using digital image processing. The results confirmed the usefulness of texture parameters of the outer surface of tomato seeds for classification purposes. The discriminative models allow to obtain a very high probability and may be applied to authenticate and detect seed adulteration.

The Effectiveness of Vacuum-microwave Drying Methods in the Preservation of Amelanchier Berries (Amelanchier canadensis L. Medik.)

In Poland, Amelanchier berries are of considerable interest to both consumers and potential producers, which presents marketing challenges and opportunities. An attempt was made to preserve Amelanchier berries using a vacuum-microwave method of drying in order to determine its usefulness for producing microbiologically stable dried fruit with a high nutritional values. The berry variety “Prince William” (Amelanchier canadensis) was chosen as the experimental material. Vacuum-microwave drying was performed in two variants: (convective drying [CD] + vacuum microwave method [VMW]) after convective pre-drying of fruit and (VMW) without pre-drying. Unassisted CD was used as the reference method. Application of a vacuum-microwave drying method to Amelanchier berries makes it possible to obtain a stable preserved product of high-quality, yielding moderate shrinkage and good retention of bioactive compounds. An optimized method of vacuum-microwave drying, applied directly to frozen fruit, allows the retention of 70 % of cyanidin glycosides present in the raw material.