The integrity of fruit bodies of the oyster mushrooms is for a significant factor in the efficiency of their storage. Fresh mushrooms can contain spores of different kinds of bacteria which will start to grow when the tissue of fruit body is broken during the packaging process. Oyster mushroom growers in Ukraine are using the standard size of polystyrene foam trays for packaging, which reduces food safety and total quality of mushroom during storage. One of the solutions to this problem can be the possibility to grow clusters sizes best suited for packaging and storage. Data about the effect of hole size on yield and number of fruit bodies in the clusters of Pleurotus ostreatus var. florida is known. The purpose of our research was to determine the effect of hole size (factor A: 50, 100 and 150 mm) and placement of substrate blocks on the shelves (factor B: horizontal, vertical and slant = 60 ° slope) on the size of clusters and biological efficiency of strain Pleurotus ostreatus 2301 IBK. This strain is the most popular in Ukraine due to fruit body morphology and good taste. The culture of tested was obtained from the Institute of Botany, NASU (Kiev). The culture was incubated on Malt Dextrose Yeast Agar (MDYA) at 24- 26 °C and used to produce spawn on a mixture of mix barley, wheat and rape seeds (10:9:1). The substrate is containing sunflower husks and barley straw (3:1). After pretreatment and pasteurization were inoculated with spawn (3.5%wet weight). The inoculated substrate blocks were in sealed polyethylene bags measuring 350 × 900 mm and a film thickness of 70 μm. The average mass of each substrate block was 12430 ± 230 g. The substrate block per treatment was replicated six times and incubated at 18 ± 2 °С. Light (200 lux) and reduced temperature (16 ± 2 °С) was introduced to the formation of pinheads after substrate blocks were fully colonized (12 days of incubation). Relative humidity of air was 87± 3 %; CO2 concentration was 1050 ± 50 ррm. The morphological characteristics of clusters and biological efficiency were determined from the first flush of harvesting. The first pinheads were observed 14-16 day from inoculation at all variants of research. The first flush of harvesting lasted 5 days from pinhead to harvesting in all experiments. Results indicated that BE in the bags set at the horizontal position was 10 % less than other variants of the experiment. The relation between hole size on substrate blocks and size of fruit body clusters was different in all variants of the experiment. The effect was more on the substrate blocks set at the horizontal position, the width of clusters was more than their height by 69-79 mm, whereas it was not more than 40 mm in other variants of the experiment. There was a linear correlation between hole size and size of fruit body clusters. The inference from the results is that knowing the right size of holes used on fruiting substrate blocks, in this case, 50 mm, can lead to clusters best for packaging and storage of oyster mushrooms in commercial operation in Ukraine.
oyster, clusters of fruit bodies, morphology, industrial cultivation, food safety, packaging