Low Temperature Refrigeration as an Alternative Anti-Pest Treatment of Dates

Abstract

-Large amounts of dates are produced and consumed around the world each year. Apomyelois ceratoniae causes main losses during storage and export of date fruit. Fumigation is the most widely used treatment to prevent postharvest losses. However, this treatment negatively affects the biological value of dates, environmental and economic parameters of production. Widespread fumigation agent methyl bromide is toxic to a human body and contributes to the destruction of the ozone layer. The aim of the current work was to find a new method based on the use of low temperature refrigeration to reduce the pest and insect infestation preserving the nutritive value of dates during cold storage at the same time. A. ceratoniae mortality under different temperatures and dates respiration rate, sugar, organic acids, pectic substances content and sensorial characteristics were studied. The results indicate that at −18 °С the A. ceratonie larva dies within 2 h, the eggs and larvaewithin 24 h respectively. Thus, it is clearly shown that there is no need in using chemicals or irradiation to prevent dates pests. Physicochemical and organoleptic proprieties of dates were satisfactory during 360 d at −18 °С and during 180 d at +4 °С. The low temperature refrigeration and storage at −18 °С is recommended for dates to prevent pests and quality losses. It is apparently advantageous for environment and climate if compared with other anti-pest treatment variants.

Effect of Physical Methods on Date Fruits Insects and Microbes

“…The conditions were time, concentration, temperature and requirements during treatment. From data in Table (7) the method of preserving dates by freezing or ozone is done in the date's production areas, while, the method of preserving dates by radiation requires transferring the dates to the commercial radiation unit outside the production areas. From the same table it was observed that the three methods lead to the main purposes, which are the final disposal of insects and their instars and the reduction of the microbial load to the allowance limits.…”

“…(from the time when the fruit temperature reaches -18•C or lower) is enough to kill all life stages of stored products insects. Lallouche et al [7] indicated that date fruits were stored at −18°С the Ectomyelois ceratoniae Zeller larvae die within 2 hrs., and the eggs and larvaewithin 24 hrs., respectively. They were recommended for storage dates at −18°С to prevent pests and improve the quality.…”

Commercial techniques for preserving date palm (Phoenix dactylifera) fruit quality and safety: A review

“… Methods/Techniques employed Advantages Disadvantages Reference Refrigeration Slow down enzymatic reactions, as well as the activity of microbial and insect’s life The efficacy of low temperatures depends on (i) the inherent initial quality attributes of the dates, (ii) the microbe and insects present at harvest, and (iii) the temperature applied. Cooling does not prevent insect infestation although it reduces it, however, insect infestation does not take place at temperature below 4 °C, but at these levels the insects will not necessarily be destroyed ( Lallouche et al, 2017 ) Fumigation Killing insect life in all its stages of development: egg, larva, pupa and adult Treatment must not be applied to fresh fruits or when stored under deep refrigeration, and the average practical dose is 15 g/m 3 for 12–24 h at 15–16 °C Fumigant is slow acting Does not stop insects to emigrate from the dates (disinfestation) and insects in various countries have developed resistance to this gas The residue levels after treatment stay within the MRL (maximum residual levels) ( El-Mohandes, 2010 , Navarro, 2006 ) Heat Treatment 100% mortality of emigration and control of nitidulid beetles in dates Cause discolouration and have a blistering effect that separates the skin from the flesh of the fruit ( Finkelman et al, 2006 , Kader, 2009 , Navarro, 2006 , Rafaeli et al, 2006 ) Modified Atmosphere Packaging (MAP) The most effective to preserve the quality maintenance of dates with limited effects on the appearance of physiological disorder signs Limited effects on the appearance of date fruits ( Al-Redhaiman, 2005 , Dehghan-shoar et al, 2010 , Kader, 2009 ) Edible Coating Improve the appearance of dates, protect the fruits, and reduce stickiness in case of soft dates Reduce water evaporation from the fruit and thereby reduce its weight loss by up to 50% and maintain the quality of the fruits Some negative influence mainly on sensory attributes and flavor ( Aboryia and Omar, 2020 ) Ozone(O 3 ) Treatment Reduce or eliminate all life stages (adults, larvae, and eggs) of Indian meal moth ( Plodia interpunctella ) and sawtooth grain beetle ( Oryzaephilus surinamensis ) The O 3 is a generally recognized as safe sanitizer in the food industry ...…”

Applying Dynamic U-Value Measurements for State Forecasting in Buildings

“…According to previous research [1], buildings contribute to 39 % of total greenhouse gas emissions and approximately 40 % of global energy consumption [2]. Furthermore, statistics [3] reveal that people spend 87 % of their time inside various types of buildings.…”