Етилен-активність яблук сорту Хонейкрісп залежно від режиму охолодження і післязбиральної обробки інгібітором етилену.

Abstract

Succesful fruit storage is based on a system of interrelated factors, the irrational use of one of them reduces its efficiency significantly. The level of losses depends on the physiological state of the fruit, so the improvement of cold storage depending on the harvest time and cooling mode is important. Honeycrisp is a winter apple cultivar of North American selection with a crispy and juicy flesh. Its fruit do not ripen at the same time, requiring multiple picks, and in the suboptimal mode of post-harvest cooling and storage they are affected by bitter pit, low-temperature breakdown and flesh browning. Post-harvest treatment of 1-MCP slows down respiration rate and ethylene emissions, helps preserve organic acids, but it has a little effect on flesh firmness and the content of dry soluble substances. The research was conducted in the storage season 2014/2015 at the Department of Fruit Growing and Viticulture of Uman National University of Horticulture. Honeycrisp apples were collected and stored in a branch of the Department - the farm «Yanis», Khotyn district, Chernivtsi region. The apples were harvested at harvesting maturity (first collection) and a week later (second collection), taking into account firmness of the flesh, content of dry soluble substances and iodine-starch test. Fruits of a homogeneous ripeness degree of the highest commercial grade were selected from typical trees of a pomology variety; accounting units were immediately formed and examined for damage, and placed into paper lined boxes. On the day of collection, the products were cooled to 5 °C overnight, followed by the storage at 2±1 °С and relative humidity 85-90% (conventional method) or cooled with a seven-day exposure at 10 °С and its subsequent decrease by 1 °С per day to storage temperature 2±1 °С. An ethylene production rate was measured in a sample of three fruits with the ICA-56 analyzer (International Controlled Atmosphere, Ltd.). After removing from the cold storage and 24-hour warming of fruits, the first measurement was done at 18...20 °C and during shelf-life at the same temperature and relative humidity of 55...60 %. It has been found out that during a 30-day shelf-life, fruit ethylene activity increases, regardless of the picking time and cooling mode. For both picking dates, post-harvest treatment of 1-MCP reduces the ethylene activity of apples with traditional cooling by 1.3–39.5 times, and with slow cooling – by 1.1–11.2 times, as compared with the fruit without such treatment. During a six-month storage duration, the highest intensity of ethylene emission was recorded for untreated 1-MCP fruit of late harvest, regardless of the cooling mode. At the end of a six-month storage period of traditionally chilled fruit, the rate for mass-harvested apples with 1-MCP treatment was 1.9 time slower (1.4 time slower for late-harvested ones), as compared with the fruit without treatment. With slow cooling, the ethylene activity of mass-harvested apples treated with 1-MCP was 5.8 times slower (1.8 time slower for late-harvest fruits), as compared with untreated fruits. It has been found out that the ethylene activity of freshly picked apples cv. Honeycrisp is mainly determined by the harvest time (39.7 % effect), post-harvest 1-MCP-treatment (28.0) and much less by the cooling regime (5.8 %). After a two- and four-month storage, the change in ethylene activity is determined by the treatment of 1-MCP (impact factor, respectively, 90.9 and 83.7 %), and after a six-month storage it is determined by the collection period (37.8 %) and the post-harvest treatment of 1-MCP (53.1 %).