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Freezing is the method usually used for preserving delicate fruit, because the product tends to maintain its original attributes, i.e., keeping its nutritional properties as close as possible to those of fresh fruit. Strawberry is a widespread and highly demanded fruit, but the fresh fruits are available in a short period of time and the largest amount of strawberry is processed by freezing. The aim of the paper is to determine the effect of process of freezing in the industrial conditions, with precooling, on the relevant parameters of the strawberry quality. The fruits were frozen in the conventional freezing tunnel by cold air temperature of –33 °C until reaching a temperature of –15 °C in the thermal center of the fruits. Packaged frozen fruits were stored in the chamber at –18 °C. In order to determine the changes in strawberry quality, the content of dry matter, total sugars and acids, pH, vitamin C, and sensory quality characteristics were analyzed. Also, quality index of the fresh and frozen strawberry is determined by calculation. The obtained results showed that there were no significant changes in the physicochemical parameters of quality after the freezing of the strawberry fruits. Significant changes are found in the sensory characteristics and the most remarkable is the loss of consistency and firmness of the frozen strawberry. Also, some modified color, taste and aroma of the strawberry fruit have been noticed after freezing in the industrial conditions.

Raspberry leaf blotch emaravirus (RLBV) is a recently characterised virus infecting raspberries reported in several European countries. RLBV causes yellow blotching, the distortion of leaf margins, and the twisting of raspberry leaves. For a long time, similar symptoms were attributed to the feeding damage caused by raspberry leaf and bud mite (Phyllocoptes gracilis). From 2014−2017, a large-scale survey was conducted in Serbia to investigate the degree of association of the observed symptoms with the RLBV infection. A total of 98 symptomatic and asymptomatic samples were collected from 30 locations. All collected samples were tested on the RLBV presence by reverse transcription and polymerase chain reaction (RT-PCR) using three sets of RNA-specific primers targeting RNA-1, RNA-3, and RNA-5 of the RLBV genome. RT-PCR analysis revealed high incidence of RLBV in tested samples (68.7%). RLBV was confirmed in raspberries ‘Fertödi Zamatos’, ‘Glen Ample’, ‘Meeker’, ‘Polana’, ‘Tulameen’ and ‘Willamette’. Twenty-one isolates were selected for sequencing the portion of the nucleocapsid (NC) gene. The nucleotide sequences of the isolates showed 93.2−100% identity. Phylogenetic analysis confirmed significant genetic variability of the Serbian RLBV isolates based on the nucleocapsid-encoding sequences and revealed the existence of two main clusters. Phylogenetic analysis of the 45 RLBV sequences from Finland, Slovakia, Scotland, and this study also confirmed the existence of two main clusters of isolates.

In vitro clonal propagation of small fruit species has been one of the most broadly exploited approaches in biotechnology. However, the most critical aspect of this propagation technology has been the maintenance of genetic fidelity of tissue culture-raised plants. In the present study, three techniques were deployed in the assessment of genetic fidelity of micropropagated plants (TC plants) of blackberry cultivar Cacanska Bestrna' and raspberry cultivar 'Meeker' in the second year after planting in the open field, in comparison to plants originating from the standard planting material (ST plants). Flow cytometry analysis deployed to estimate the DNA ploidy level and relative nuclear DNA content in TC and ST plants revealed no significant differences in nuclear DNA content between plants of different origin. Chromosome counting in root/shoot tip meristems also showed a normal tetraploid chromosome number (2n = 4x = 28) in TC blackberry plants and a normal diploid chromosome number (2n = 2x = 14) in TC raspberry plants. Polyacrylamide gel electrophoresis of peroxidase (POX) extracted from the leaf tissue revealed no differences in POX profiles between TC and ST plants either. The results obtained in this study verify the suitability of micropropagation by axillary branching for commercial exploitation in blackberry and raspberry.

Biological and chemical properties of cv. Willamette were contrasted with those of cvs Tulameen, Latham, Meeker and K81-6 grown under agro-environmental conditions of Western Serbia. The following parameters were examined: yield per unit land area, total dry matter content, soluble solids content, total reducing sugars, total acids content, pH value, total pectines and total anthocyanins. The obtained results showed that cvs Willamette and Meeker had exceptional yield potential and highest quality fruits, which renders them suitable for both fresh use and various forms of processing, whereas cv. Tulameen can be recommended for fresh consumption only. K81-6 is recommended for processing and fast freezing after harvesting.

The objective of this study was to test yield and fruit quality of the red raspberry 'Meeker' and the blackberry 'Cacanska Bestrna' propagated using the standard method (ST) and in vitro, by tissue culture (TC). The monitored parameters included the total number of canes, cane number per one metre of the planted row, yield per cane (raspberry) or per bush (blackberry) and total yield. Monitoring fruit quality parameters included the weight and dimensions of fruit, the number, weight and dimensions of individual drupelets and weight of drupelet seeds. No significant differences were determined either for the total number of canes and/or the cane number per row metre in plants originating from both types of planting material in both genotypes. Significant differences were observed to the advantage of the raspberry ST plants, in the total yield, as well as the fruit weight in the blackberry ST plants. A significantly higher weight of drupelet seeds was observed in TC plants of both genotypes. Concerning the organoleptic assessment of fruits, no significant differences were recorded between fruits coming from ST and TC plants.

A two-year research was conducted on volatile compounds of raspberry cultivar 'Meeker' and blackberry cultivar 'Cacanska Bestrna' fruits, harvested at full ripeness and collected from plants propagated by both standard vegetative technique (by suckers from adventitious root buds for raspberry and tip layering for blackberry) and in vitro micropropagation. Out of the total number of volatile components, key aromatic components were selected, having a decisive impact on the aroma of raspberry and blackberry fruits. In both experimental years (2011-2012), contents of 48 key aromatic components were compared in the raspberry fruits, whereas 53 key aromatic components were quantified and compared in the blackberry fruits. These components were further classified in alcohols, aldehydes, ketones, acids, esters, terpenes, sesquiterpenes, lactones, C13 norisoprenoids (only in raspberry fruits), hydrocarbons (only in raspberry fruits) and phenols (only in blackberry fruits). No significant differences have been established in the presence of certain volatile aromatic components in the raspberry fruits collected within the same year from plants produced using the standard method, compared to plants obtained by in vitro micropropagation. The same trend was established in blackberry fruits.