Sustainable development of Medjool date cultivation in Jericho: improvement of quality management and evaluation of
multifunctional properties Leonardo Borsacchi1, Patrizia Pinelli2
1 ARCO (Action Research for CO-development) c/o PIN Scrl - University of Florence, Italy, leonardo.borsacchi@pin.unif.it
2 Department of Statistics, Computer Science, Applications (DiSIA) - University of Florence, Italy and ARCO (Action Research for CO-development) c/o PIN Scrl - University of Florence, Italy patrizia.pinelli@unifi.it
Abstract
Date palm (Phoenix dactylifera L., cv. Medjool) is a millenary cultivation and an important income generator for Palestinian people. Plantations are mainly located in the Jordan Valley. Actually, despite the potential high quality of Palestinian Medjool dates, the export to Europe still faces many difficulties due to product variability in size and loose skin.
This study took place within the project “Sostegno alla riorganizzazione produttiva, manageriale e
commerciale delle cooperative di datteri palestinesi ed egiziani” (AID 10601), implemented by Jean
Paul II Foundation and funded by the Italian Agency for Development Cooperation. The main objective of the project is to enhance the quality management among farmers’ member of PFCA cooperative, based in Jericho, through the definition and introduction of new procedures and best practices. Along this goal, there is a first exploration of the main issues affecting the quality of dates production with particular attention for the antioxidant content of date fruits and seeds and the corresponding antiradical activity.
The results reported in this paper consist in the data collected during a field research mission held in Jericho and Jiftlek in September 2017. The adopted methodology consisted, firstly, on the active involvement of the project stakeholders, including desk-based analysis of reports; conduction of semi-structured interviews with a sample of date producers, on field visits during the activities of harvest and sorting, meeting with local stakeholders; secondly, in an analytical approach aimed at the discovering of the potential biological properties and multifunctional applications of dates. Regarding the production of dates in Jericho, we should remark that the nutritional quality of date fruit is strongly related to the polyphenolic antioxidants. Though a high nutritional value and health benefits have long been demonstrated for date flesh (Baliga et al., 2011), date seeds demonstrate an excellent nutritional quality, due to high amounts in fibers, minerals, vitamins, and phenolic antioxidants (Habib et al., 2014). The characterization of the antioxidant profile of flesh and seed tissues of Medjool date by HPLC/DAD method and the evaluation of the antiradical properties assessed by DPPH test show the presence of different polyphenol classes, i.e. hydroxycinnamic acids, flavonoids and tannins.
The first results of our investigation highlight the importance of P. dactylifera L. (cv. Medjool) as a promising source of functional ingredients and boost its potential use in the food and nutraceutical
industries. Thus, Palestinian dates, with a systematic implementation of standardized procedure, could really improve the quality and becoming a widely exportable product on the European market.
Keywords: Sustainable food commodities, Agrifood chain, Quality management, Antioxidant
compounds, HPLC/DAD
1. Introduction
This study took place within the two-year long project “Sostegno alla riorganizzazione produttiva,
manageriale e commerciale delle cooperative di datteri palestinesi ed egiziani” (AID 10601),
implemented by Jean Paul II Foundation and funded by the Italian Agency for Development Cooperation. The main objective of the project is to enhance the overall quality and sustainability of the managerial and strategic organisation of a target group of date producers in Palestine, part of the Palm Farmers Cooperative Association (PFCA).
The date palm (Phoenix dactylifera L.), one of the oldest plants cultivated by mankind, is broadly distributed in many regions of the world, including Asia, Africa, Arabian countries, and the Middle East. The worldwide production of P. dactylifera fruits is about 7.5 million tons (FAOSTAT, 2016). Date palm cultivation in the Palestinian territories exists in the regions of Jericho and the Jordan Valley, in the West Bank and in the Gaza Strip. The Mediterranean climate, dominant in the area, provides optimal conditions for growth and development of date palm. It is estimated that 5000 tons were produced in Palestine in 2015. Several constraints face date cultivation and development, including high investment costs, lack of marketing strategies and concurrence by Israeli production, together with a limited availability of water. There are hundreds of named varieties of P. dactylifera date palms, and one of the most famous is the large soft Medjool date palm. The area of Jericho possesses a comparative advantage for growing Medjools. The climate in the region, where temperatures range from 12 °C in March up to 50 °C between July and October, is considered ideal for Medjool production, which requires hot and dry weather.
This paper presents the first findings of an in-field research mission conducted in Jericho and Jiftlek in September 2017 by ARCO, a university action-research centre founded in 2008 at PIN S.c.r.l. (Polo Universitario “Città di Prato”) – University of Florence.
2. Methods
With the aim to improve the technical and productive competencies and procedures of the farmers of PFCA, this study has focused in particular on the following specific objectives:
i) to understand more about the existing procedures (in particular harvest and selection steps) of a sample of selected farmers part of PFCA, with the aim to collect relevant information and evaluate the possibilities to share existing best practices among all the members;
ii) to explore the main issues affecting the quality of dates production and their linkages with internal and international markets, also assessing potential areas of interventions;
iii) to understand if the content in polyphenolic molecules and antioxidant properties of the investigated fruits is also influenced by actual production procedures. At this stage, the attention is focused at the characterization and quali-quantitative evaluation of natural compounds present in these vegetal matrices. The chemical characterization and the quantitative evaluation of these minor polar compounds in different date tissues can be useful to recover active principles with important applications in herbal, cosmetic, besides functional food supplements ingredients.
Further activities of the research will also include in the future the realization of a pre-feasibility study for the combined use of polyphenolic molecules obtained from the involved matrices in new design products for use in herbal drugs and cosmetics.
2.1 On field assessment
The adopted methodology actively involved the project stakeholders. In particular, the activities conducted before and during the field mission were: a) Desk-based analysis of internal reports (e.g. field mission reports, farmers’ profiles) prepared by CNR, Slow Food and Jean Paul II Foundation, as well as publications of studies conducted by national and international research centers. b) On field conduction of semi-structured interviews with a sample of 5 farmers, members of PFCA, along with on-site sustainability audit of their fields and farms during the activities of harvest and sorting. c) Conduction of semi-structured interviews with representatives of Jericho Chamber of Commerce, Industry and Agriculture.
2.2 Extraction and HPLC/DAD analysis of date fruits
The collected samples of date fruits (flesh and seed) were reduced in powder and extracted with a hydroalcoholic solution (ethanol/acidic water 7:3 at pH 3.2). The raw extract was also fractionated by an Extrelut® cartridge and using exan, ethylacetate and methanol as elution solvents. The ethylacetate fraction was evaluated for its content in low molecular weight polyphenol, without the interference of sugars. The characterization and the quali-quantitative evaluation of polyphenol compounds was carried out by HPLC / DAD analyses performed with an HP 1100L instrument equipped with an HP DAD (Agilent Technologies, Palo Alto, CA). In particular, the analytical column used was Luna C18 250×4.60 mm, 5μm (Phenomenex), according to a previuous method (Abu-Reidah et al., 2017), slightly modified.
2.3 Quantitative analysis
In order to calibrate the individual polyphenolic compounds, specific calibration curves (R2
≥0.998.) of 5-level of concentration were built using standard substances (98-99% of purity). In case of lack of the specific molecule, the calibration was carried out with compounds having similar chromophore, measuring the absorbance at the maximum UV absorption. In details, the amount of ferulic acid was
calculated at 330 nm, using pure ferulic acid as a reference; caffeic acid derivatives were evaluated at 330 nm, using chlorogenic acid (5-O-caffeoylquinic acid) as standard; gallic acid and the other compounds (tannins) with similar chromophore were evaluated at 280 nm, using a standard solution of gallic acid; finally, the flavonoids were calibrated at 350 nm using a standard of luteolin-7-O-glucoside.
2.4 Folin-Ciocalteau assay
Total polyphenols were determined as follows: the hydro-alcoholic date extract (125 μL) was mixed with 500 μL of water and 125 μL of Folin-Ciocalteau reagent and allowed to stand for 6 min; 1250 μL of a solution of sodium carbonate (7%) was added to the mixture. After 85 min, the absorbance of centrifuged samples was measured at 725 nm against water as a blank, by using a DAD 8453 spectrophotometer (Agilent Technologies). The amount of total phenolics is expressed as Gallic Acid Equivalents (GAE, mg gallic acid / g of sample, on Dry Weight basis), through the calibration curve of gallic acid. The calibration curve range was 20 - 500 μg/mL (R2 =0.9976).
2.5 Diphenyl-picryl-hydrazyl radical (DPPH) test
The antiradical capacity of the extracts was estimated according to a previously reported procedure (Heimler et al., 2005), with slight modifications. The antiradical activity (AR%) was calculated through the following relationship:
[AR% = 100 (A0−A20)/A0]
where A0 and A20 were the absorbance of DPPH, at time 0 and 20 min., respectively, after adding the diluted extract. The EC50 of the extracts was determined through the use of five-point linearized curves [AR%-ln (concentration in polyphenols)], built determining AR% for five different dilutions of each extract and then by calculating the molar concentration in polyphenols of the solution that inhibits the DPPH activity to 50%.
This paper outlines the first findings that will been implemented in the future with further investigations and analyses.
3. Results and Discussion
The target cooperative PFCA, formed by 117 members, was funded in 1996, counting a total of around 400 date producers operating in the area of Jericho and Jiftlek. It aims to collect and to invest the fees of the members in order to build facilities for common use. Main cultivation of the cooperative’s members is palm tree, although some of them tried in the past to cultivate other crops in addition to palms. No activities of stocking, processing and treatment are directly managed by PFCA and single associates manage the post-harvest steps at their own.
The introduction of new quality procedures among the members of PFCA could foster more sustainable behaviour and improve commitment among them. In particular, the aim is to obtain a more sustainable chain, with reference to: a) Environmental sustainability, i.e. guaranteeing the integrity of ecosystems (e.g. through appropriate irrigation, fertilization, pest control and weeding practices); b) Economical
sustainability, i.e. generating long-term income; c) Socio-cultural sustainability, i.e. guaranteeing fair access to fundamental rights and conditions of well-being, within the workers and within the community, providing opportunities to create and develop internal and external relations involving the community, and recognizing the cultural value of a food commodity.
Table 1 outlines the main results of the current situation of the visited PFCA’s planters, emerged by the on field assessment.
Table 1.Comparison among members based on authors' on field assessment. Source: Authors
As well as the assessment of the current situation of managerial issues of the PFCA’s members, we carried out a quality evaluation of the actual production, in order to define possible new market destinations. As previously reported, fruits and vegetables are an important source of dietary antioxidants and several epidemiological studies show that their regular intake in the diet may decrease the risk of several chronic diseases. Date fruits are among the most nourishing natural food available to humankind and are knew to have numerous health benefits. Rich in vitamins and minerals, the date fruit
Planter #1 Planter #2 Planter #3 Planter #4 Planter #5
E n v ir o n m e n ta l is su e s Main environmental strengths Willing to introduce eco-friendly fertilisation // Try to be like organic Clean and organized // Main environmental weaknesses No full technical awareness about fertilisation Lack of waste disposal Lack of waste (e.g. leaves and bushes) disposal // Lack of waste disposal S o ci a l is su e s Main social strengths Good organisation of work time-shifts Air conditioners in the workspace Family involvement Workspace designed according international safety and hygiene standards // Main social weaknesses Absence of personal protective equipment Absence of personal protective equipment Absence of personal protective equipment // Absence of personal protective equipment E co n o m ic i ss u es Main economic strengths Stable financial status Stable financial status Use of social networks to sell dates on the local market Export to Europe, Turkey, Arab countries, Russia. Stable financial status Main economic weaknesses Cheap price of dates on local market, concurrence on international markets Cheap price of dates on local market Cheap price of dates on local market // Lack of marketing strategy
is a good source of high nutritional value food. In particular, the soft dates have higher moisture content, a mild flavor, relatively low sugar and a fair amount of antioxidants, as the phenolic compounds (hydroxycinnamic acids, tannins and flavonoids). Antioxidant phytochemicals present in foodstuffs are the main responsible for such health benefits. Moreover, date seeds, which constitutes between 10% and 15% of date fruit weight, can be an interesting source of phytochemicals. The date seeds are often considered a waste product of many date processing plants producing pitted dates, date syrup and date confectionery. At present, seeds are used mainly for animal feeds in the cattle, sheep, camel and poultry industries, but date seed concentrates could be an important and inexpensive source of fibers and antioxidants.
Table 2 shows the antioxidant content in the investigated samples, reporting the results of both raw and purified extract, as detailed in the caption. It is interesting to underline the very higher content of phenol compounds in seeds with respect flesh in the raw extracts. The functional properties of date seeds have been already reported by (Ali Al-Farsi et al., 2008), evidencing in the seeds a composition of phenolics of 3102–4430 mg gallic acid equivalents/100 g, and by (Habib et al., 2014) which reports a content of phenolics of 24.6 g kg−1 gallic acid equivalent. Both results are assessed by the Folin-Ciocalteau test and are slightly higher with respect our results for the cultivar Medjool, but it depends by the use of more efficient extraction solvents, and then, our results presumably underestimate the actual antioxidant potential of date seeds. The work of (Habib et al., 2014) reports a total amount of flavonoids and phenolic compounds in date seed of about 50.72 g kg−1, being the main class of compounds the flavan-3-ols in both their monomeric and polymeric forms, representing almost 99% of total polyphenols. Such results indicate date seeds as a very rich source of bioactive compounds, thus constituting strong candidates for functional food additives and nutraceuticals.
Table 2. Total polyphenolic content of raw extracts and single phenol classes in purified extracts of
date tissues (flesh and seed) from cultivar Medjool. Data are the average values (±SD) of triplicate samples and are expressed as mg/100g dw. aHydroalcoholic solution (ethanol/acidic water 7:3 at pH
3.2) evaluated by Folin-Ciocalteau test. bEtylacetate fraction from Extrelut® cartridge evaluated by
HPLC/DAD analysis. Raw Extracta Date Flesh Raw Extracta Date Seed Purified Exctractb Date Flesh Purified Exctract b Date Seed TANNINS
(as gallic acid) 2.954±0.13 1.078±0.02
HYDROXYCINNAMIC ACIDS
(as ferulic acid) 4.229±0.39 1.237±0.27
FLAVONOIDS
(as quercetin
3-O-glcoside) 0.641±0.16 ND
TOTAL
The interesting functional properties of date seed have been assessed by measuring the antiradical potential by DPPH test. In particular, reporting the data of EC50 as the quantity in mg of date fruit that inhibits 1 mg of radical, the EC50 of the hydroalcoholic extracts of date flesh was in the range 167-285 mg, whereas a value of 0.75 mg was registered for the EC50 of date seeds. It means date seed extracts are on average three hundred times more active than extracts obtained from date flesh. Figure 1 shows the logarithmic curve of the radical inhibition in function of the hydroalcoholic extract concentration (as mg of date seed per mL).
Figure 1. Logarithmic curve describing the relation between concentrations of the hydroalcoholic
date seed extract and the percentage of inhibition of DPPH radical.
4. Conclusions
Regarding the production of dates in Jericho, we should remark that some issues on quality are due to the lack of adoption by producers of standardized methods. Thus, Palestinian dates, with a step-by-step implementation of standardized procedures, along with the adoption of effective marketing strategies, could really improve their quality to be ready to face potential new markets and opportunities for this commodity.
Concerning the analytical research, the first results show that Medjool date is a good source of natural antioxidant compounds belonging to different polyphenolic classes, and such composition accounts for the antioxidant and antiradical properties of the fruit. Particular attention must be devoted to very high antiradical potential of date seeds. It is worth of noting that, as in the case of any other crop cultivation, there are periods with an excessive concentration of date fruits on the market. Moreover, in Palestine a good equipment for storage and preservation it is not available yet. Hence, the processing of Medjool dates and the utilization of seeds to obtain new products is very important to increase the income in this sector, in particular for such dates, which do not belong to the premium price category.
y = 0,1319ln(x) + 0,9641 R² = 0,8278 0% 20% 40% 60% 80% 100% 120% 0 0,2 0,4 0,6 0,8 1 1,2 1,4
Further activities, after the assessment of antioxidant properties of the Medjool date, could be requested for the definition of new procedures for the members of PFCA, in order to foster more sustainable behavior and improve commitment among them by sharing same practices, with the aim to obtain a more sustainable chain. Within this perspective, in the future the production of dates could be carried out using ecofriendly procedures in order to obtain also biologically active compounds useful for nutraceutical and cosmetic applications and markets in addition to date production for the ready-to-eat market.
References
Abu-Reidah I.M., Gil-Izquierdo A., Medina S., Ferreres F., 2017. Phenolic composition profiling of different edible parts and by-products of date palm (Phoenix dactylifera L.) by using HPLC-DAD-ESI/MSn. Food Res Int, 100, 494–500. Ali Al-Farsi M., Yong Lee C., 2008. Optimization of phenolics and dietary fibre extraction from date seeds. Food Chem, 108, 977–985.
Borochov-Neori H., Judeinstein S., Greenberg A., Volkova N., Rosenblat M., Aviram M., 2015. Antioxidant and Antiatherogenic Properties of Phenolic Acid and Flavonol Fractions of Fruits of ‘Amari’ and ‘Hallawi’ Date (Phoenix
dactylifera L.) Varieties. Journal of Agricultural and Food Chemistry, 63(12), 3189–3195.
Habib H.M., Platat C., Meude E., Cheynier V. and Ibrahim W.H., 2014. Polyphenolic compounds in date fruit seed (Phoenix
dactylifera): characterization and quantification by using UPLC-DAD-ESI-MS. J Sci Food Agric 94, 1084–1089.
Heimler D., Vignolini P., Dini M.G., Romani A., 2005. Rapid tests to assess the antioxidant activity of Phaseolus vulgaris L. dry beans. J Agric Food Chem 53, 3053–3056.
http://www.fao.org/faostat/
Nasir M. U., Hussain S., Jabbar S., Rashid F., Khalid N., Mehmood A., 2015. A review on the nutritional content, functional properties and medicinal potential of dates. Science Letters, 3, 17–22.
Ou B., Hampsch-Woodill M., Prior R.L., 2001. Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe. J Agric Food Chem, 49, 4619–4626.
Russo G., Dalla Ragione I., Fantinati L., Simonetti C., Lauteri M., 2017. A Socio-ecological Analysis of the Date Palm (Phoenix dacylifera L.,) System in Jericho Area Palestine, in: Kallel A., Ksibi M., Ben Dhia H., Khélifi N. (Eds.) Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions, p. 1425-1427, Springer. Yasin B. R., El-Fawal H. A. N., Mousa S. A., 2015. Date (Phoenix dactylifera) polyphenolics and other bioactive compounds: A traditional Islamic remedy's potential in prevention of cell damage, cancer therapeutics and beyond. International Journal of Molecular Sciences, 16(12), 30075–30090.
