Postharvest treatment
After harvesting, fruits should be graded according to the degree of ripening and fruit size, then stored under low temperature, dried, or processed. Dehydrated jujube fruits can be obtained by drying under the sun for about three weeks or in a cabinet drier at 60°C for 36–48 hours until the moisture content reduced to less than 25%. The dried fruit can be consumed as such or further processed into juice, wine, powder and so on. For more information see Jujube quality management
Fruit quality testing
Two internal maturity parameters should be tested: total soluble solids and citric acid content (used to calculate sugar-acid ratio). Sugar levels are a commonly used measurement in a wide range of crops. The percentage sugar, measured in degrees Brix (°Brix), indicates the sweetness of the fruit by measuring the number of soluble solids in the juice.
A hand-held refractometer can be used to measure total soluble solids (percentage sugar/°Brix). Acid content of juice from jujube fruits can be measured using a pH meter. The sugar-acid ratio contributes to the unique flavour of the fruit and can be calculated by dividing the degrees Brix by the citric acid concentration.
Tests on fruit grown in Western Australia found that the variety Li had the highest level of total soluble solids (31°Brix) of the three varieties tested and Chico had the lowest (25°Brix). Chico had around double the amount of acid as Li and Suimen and therefore the lowest sugar-acid ratio of the three varieties.
Storage practices
Pests and diseases
Jujube fruit is very perishable and highly susceptible to postharvest decay. Blue mould caused by Penicillin expansum is one of the most serious postharvest diseases of jujube in China.
Storage and processing
Fresh jujube fruit cannot be stored for a long period under ambient conditions due to its perishable nature. Its shelf life is usually only two to three days without any treatment. Studies have shown that semi-red fresh fruits can be kept crisp for over 100 days if packed in 0.04–0.07mm vented polyethylene bags and stored at -1 to 1°C, with relative humidity and CO2 concentration kept within 90–95% and 5% respectively. Dried fruit can be stored for up to 12 months in a dry, cool and sheltered environment.
Storage is not an issue in WA yet as demand is greater than supply so the fruit does not get stored for long. However, as the industry grows and fruit is exported either interstate or overseas then the development of storage techniques and transportation will be a priority.
Markets
Small quantities of Chinese jujube are grown in WA and sold at local markets and some Asian supermarkets in Perth. There is an opportunity to market the fruit both internationally and into the local market as a fresh or dried product.
In 2017, fresh jujubes were sold in Perth at wholesale prices from $8–20 per kilogram. Local dried product sells at retail prices ranging from $25–45 per kilogram.
Western Australia’s proximity to South East Asia and its counter-seasonal production to the northern hemisphere provide an opportunity to market product for the increasing demand, especially during festivals. Target markets include China, Singapore, Malaysia, Hong Kong and Taiwan.
The jujube industry in Australia has the potential to be a new profitable agricultural business to meet the requirements of domestic and overseas markets. The development of a jujube industry will be beneficial in fighting salinity and water shortages which are challenges facing sustainable agriculture in Australia.
West Australian Jujube Growers Association Inc.
The West Australian Jujube Growers Association Inc. was formed in December 2013. It is the representative industry body of jujube growers, formed to strengthen and grow the industry in Western Australia. Its aim is to work with industry and government bodies to implement consistency in all aspects of jujube production and marketing. For more information or to become a member email wajujubegrowersassociation@gmail.com.
Acknowledgements
This work was funded by AgriFutures Australia (formerly Rural Industries Research and Development Corporation) and DPIRD with support from the Western Australian Jujube Growers’ Association.
References
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Liu, M. 2006 ‘Chinese Jujube: Botany and Horticulture’ Horticultural Review, Volume 32 (ed J. Janick), John Wiley & Sons, Inc., Oxford, UK.
Li, J.W., Fan, L.P., Ding, S.D., Ding, X.L., 2007. 'Nutritional composition of five cultivars of Chinese jujube'. Food Chemistry 103, 454–460.
Yan, G and Ferguson, AR 1993 ‘The Chinese Date or Chinese Jujube’ Horticulture in New Zealand, vol 4 number 2, pp 13–18.
Yao, S. 2013 ‘Past, Present and Future Jujubes-Chinese Dates in the United States’, Hort Science, American Society for Horticultural Sciences.