Subscribe Now Subscribe Today
Research Article
 

Impact of Pretreatments and Drying Temperatures on Quality of Siwi and Sakkoti Dates



Amira Sh. Shawky, Mohamed S. Abbas, S.M.H. Rabie, M.T.M. Assous and M.A. Mostafa Zeinab
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail
ABSTRACT

Background and Objective: Drying of date helps in preserving it to be consumed outside the harvest season and removes some moisture from dates and also slows down the action of date endogenous enzymes. This study was carried out to investigate pretreatments and drying temperature on the physical and chemical properties of 2 date varieties (Siwi and Sakkoti) at the khalal stage. Materials and Methods: The date fruits at khalal stage were dipped in ascorbic acid solution, sodium metabisulfite solution and sulfur dioxide before cut into pieces, halves and as whole. Then dates were dried at 50, 55, 60 and 65°C, respectively till ~20% moisture content and examined the physical and chemical properties of dried dates. Results: Moisture content of Siwi and Sakkoti at the khalal stage was 56.90 and 51.72%, respectively, while total sugars were 79.76 and 75.74%, respectively on dry weight bases. The color of dates Hunter (L and b) were the highest of treated with meta-bisulfate solution or sulfur dioxide and the lowest of color date observed (Hunter, a) comparing with control and ascorbic acid. Conclusion: The pretreatments indicated that the dipping dates in sodium meta-bisulfate solution or sulfur dioxide then, dried at 60˚C produce high quality parameters of semi-dry dates comparing control and ascorbic acid.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

Amira Sh. Shawky, Mohamed S. Abbas, S.M.H. Rabie, M.T.M. Assous and M.A. Mostafa Zeinab, 2020. Impact of Pretreatments and Drying Temperatures on Quality of Siwi and Sakkoti Dates. Pakistan Journal of Biological Sciences, 23: 658-666.

DOI: 10.3923/pjbs.2020.658.666

URL: https://scialert.net/abstract/?doi=pjbs.2020.658.666
 
Copyright: © 2020. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

INTRODUCTION

Date palm (Phoenix dactylifera L.), a tropical and subtropical tree, belonging to family Palmae (Arecaceae) is one among man kind's oldest cultivated plants and- in the Arabian Peninsula. Date fruits have rich content of essential nutrients which include carbohydrates, minerals, dietary fibers, vitamins and small amounts of fat and protein. Egypt is ranked the first internationally concerning the amount of production of different dates, however, very little amounts are directed for export due to lack in awareness, technology and facilities for post-harvest treatments, processing and packaging. Dates have played an important role in the daily life of the people for last 7000 years1. World production of dates has increased significantly and steadily over the last 30 years. Arab countries produce about 74.5% of world total production. Egypt is the largest world's top ten producers of dates2. Egypt produces 1.68 million tons of date fruits, which represents 15.1% of the total production of Egyptian fruits (11.15 M tons). Only 16.5% of total date fruit production (278000 tons) was directed for food processing3. Date fruits have great importance in human nutrition owing to their rich content of essential nutrients which include carbohydrates, minerals, dietary fibers, vitamins and small amounts of fat and protein4. Dates are good source of rapid energy (carbohydrate content, 70-80%) and provide 274-300 k.cal of energy from 100 g of the flesh date. Most of the carbohydrates in dates are in the reducing sugars form of (fructose and glucose)5. Fresh soft date has easily eaten. Thus, for these qualities, dates are being used for breakfast during the holy month of Ramadan all over the Muslim world6. Dates are also used as component in food preparation such as sweets, snakes, confectionery, baking products, institutional feeding and health foods7. Drying of date helps in preserving it to be consumed outside the harvest season. Drying removes some moisture from dates so that bacteria, yeast and mold cannot grow and spoil the dried dates and also slow down the action of date endogenous enzymes8. However, a disadvantage of hot air drying causes serious damage to quality attributes of the products such as flavor, color, texture and valuable nutrients9. This investigation aimed to, evaluate the effects of pre-treatments and dying temperature on some quality attributes of Siwi and Sakkoti dates so that improving product quality and preserving the nutritional value.

MATERIALS AND METHODS

Date palm fruits (Phoenix dactylifera L.) Siwi and Sakkoti date varieties at the end khalal stage were obtained from Bahria Oases and Aswan Governorate, respectively in September 2018, Egypt. Sodium metabisulfite, sulfur and ascorbic acid were purchased from El-gomhoria Company, Egypt. The study was carried out at the department of Food Engineering and Packaging, Food Technology Research Institute, Agricultural Research Center, from September 2018- August 2019.

Processing methods
Preparation for dates before pretreatments: The date fruits were exposed to steam for 3 min at atmospheric pressure to inactivate enzymes and soften the texture of date fruits, then cooled in tap water according to Degefa et al.10.

Pretreatments for dates before drying: The dates from each cultivar were divided into 4 groups, then treated as follows: The first group of dates was dipped in ascorbic acid solution (0.5%) for15 min. The second group of dates was dipped in sodium meta-bisulfate solution (0.5%) for 15 min. The third group of dates was treated with sulfur dioxide in an enclosed room and the concentration of sulfur used to burn was 29 g m3 for 12 h. The fourth dates a control without previous treatments.

After pretreatments the fourth treatment was divided into 3 groups follows, the 1st group was dried as the whole date after treated with above treatment, the 2nd group was dried as half date after treated with the above treatment and the 3rd group was dried as pieces' date after treated with above treatment.

Drying process: The treated date with different pretreatments and control as whole fruits, halves and pieces were dried at 50, 55, 60 and 65°C, respectively till ~20% moisture content.

Color measurement: International color measurement L, a and b values of fresh date fruits as well as the dried date samples was measured using Minolta Chroma Meter, model CR-200. Calibration was done by a white plate before use. Color changes were quantified for L, a and b which refers to yellow tonality as was described by Barbagallo et al.11. Color measurement of whole date fruits were measured in terms of (CIE) Hunter L, a, b, H and C values where L-value measures the degree of lightness ranging from black, a-value measures the greenness to redness and b-value measures the blueness to yellowness. H-value is the hue angle which may be defined as the angle between the hypotenuse and 0 on the (bluish-green/red-purple) axis, H-value is calculated from the arctangent of b/a. H-value should remain positive between (0 and 360) of the color wheel and C-value is calculated from a and b. It represents the hypotenuse of a right triangle created by joining (0,0), (a, b) and on index somewhat analogous to color saturation or intensity as was described by Hunter12 and Little13.

Chemical analysis of fresh and dried dates: Total soluble solids (TSS) were determined by Abbe refractometer at 20°C and the pH value was measured using a Beckman pH meter. Moisture content, acidity, fiber, ash, protein, reducing, non-reducing and total sugars, were determined according to AOAC14. Tannins content was determined according to Makkar et al.15. Total phenols were determined calorimetrically using the Folin-Ciocalteu reagent as was described by Wolfe et al.16, using a UV-1601 spectrophotometer (Shimadzu, Kyoto, Japan). The concentrations are expressed as milligrams of gallic acid equivalents per 100 g of date.

Statistical analysis: The results of color measurements of fresh dates and dried dates were statistically analyzed using SPSS statistical package17.

RESULTS

The moisture content, total soluble solids, pH value, acidity, total phenols, tannins, ash, crude proteins, crude fiber, total sugars, reducing sugars and non-reducing sugars and color measurements L, a, b, C and H values of Siwi and Sakkoti cultivars at khalal stage in Table 1.

Effect of pretreatments and drying temperature on the moisture content of dried date products: The moisture content decreased with increasing drying temperatures. So, the highest moisture content value 21.63% in control whole fruits at 50°C and the lowest value 19.21% for pieces of date fruits pretreated with sulfur dioxide and then dried at 65°C (Table 2). Also, the moisture content of dried Sakkoti date products was listed in Table 3. The highest moisture content value 20.53% was recorded for whole date fruits pretreated with sodium meta-bisulfate and dried at 50°C and the lowest value was 17.45% for pieces of date fruits treated with ascorbic acid at 65°C.

Effect of pretreatments and drying temperatures on pH value and acidity of dates: The effects of pretreatments and drying temperatures on pH value and acidity of Siwi are clearly shown in the Table 4. The pH value increased with increasing drying temperature which reported pH at 50°C less than that at 65°C but the size of the date fruits had no effect on pH value. The measurement of acidity (expressed as malic acid) of Siwi dried products indicated increasing acidity by the pretreatments and decreasing by increasing drying temperature.

The pretreatments and drying temperatures effect on Sakkoti dried products in Table 5. The highest pH value 6.53 was recorded for control whole date fruits at 65°C and the lowest value, 5.38 for whole date fruits pretreated with sulfur dioxide and dried at 50°C.

Table 1:
Physical-chemical properties of date fruits varieties at khalal stage (on dry weight bases)
L-value measures the degree of lightness ranging from black, a-value measures the greenness to redness and B-value measures the blueness to yellowness, H-value is the hue angle which may be defined as the angle between the hypotenuse and 0 on the (bluish -green /red -purple) axis, H-value is calculated from the arctangent of b/a, H-value should remain positive between (0 and 360) of the color wheel, C-value is calculated from a and b, It represents the hypotenuse of a right triangle created by joining (0,0), (a, b) and on index somewhat analogous to color saturation or intensity

Table 2: Effect of pretreatments and drying temperature on moisture content (%) of siwi date

Table 3: Effect of pretreatments and drying temperature on moisture content (%) of Sakkoti date

Table 4:
Effect of pretreatments and drying temperature on pH value and acidity as malic acid (%) of siwi date (Dry weight bases)

Effect of pretreatments and drying temperatures on total phenols content of dried date products: Regarding dried Siwi date products, data of total phenols in Table 6. Total phenols ranged from the lowest value 0.428% for control whole date fruits dried at 50°C to the highest value 0.507% for date pieces pretreated with sulfur dioxide and dried at 65°C. Total phenols of Sakkoti dried products were ranged from the lowest value 0.648% for control whole date fruits dried at 50°C to highest value 0.715% for pieces' date fruits pretreated with sulfur dioxide (Table 7).

Effect of pretreatments and drying temperatures on sugar contents of dates: The total, reducing and non-reducing sugars contents of Siwi and Sakkoti date fruits (Table 8 and 9).

Table 5: Effect of pretreatments and drying temperature on pH value and acidity as malic acid (%) of Sakkoti date (dry weight bases)

Table 6: Effect of pretreatments and drying temperature on phenol content (%) of Siwi date (dry weight bases)

Table 7: Effect of pretreatments and drying temperature on phenol content (%) of Sakkoti date (dry weight bases)

From these results, total sugars and non-reducing sugars decreased with increasing drying temperature while reducing sugars increased by increasing drying temperature.

Effect of pretreatments and drying temperature on the color of whole dates: Color measurements of pretreated whole date fruits dried at different temperatures in Table 10 in terms of Hunter L, a, b, H and C values.

For each date cultivar, means in a row (comparisons among pre-treatments means within each drying temperature) sharing same upper case letter(s) are not significantly different at p<0.05, means in a column (comparisons among pretreatments means within each drying temperature) sharing same lower case letter(s) are not significantly different at p<0.05.

Table 8: Effect of drying temperature on sugar contents (%) of Siwi date (dry weight bases)
RS: Reducing sugars, NRS: Non-reducing sugars, TS: Total sugars

Table 9: Effect of drying temperature on sugar contents (%) of Siwi date (dry weight bases)

DISCUSSION

The chemical composition of Siwi and Sakkoti date fruits this results in agreement with Al-Farsi et al.6 who reported that moisture content of fresh date was 42.49% and Zaitoon et al.18 reported moisture content in khalal stage 67.22%, crude fiber 3.71%, crude protein 2.11%, ash 0.86%. Data were also in agreement with Nezam El-Din and Abd El-Hameed19 who reported that total acidity, total sugars, reducing sugars, total phenols were 0.45%, 72.6%, 63.1%, an d 0.66%, respectively. The results of tannins were similar to that of Al-Hooti et al.20 who reported 0.4% for tannins value and in agreement with Al-Farsi and Lee21 who reported TSS of date fruits 30-45 Brix at khalal stage. Also, Mohamed et al.22 reported total phenols content of 35.82 and 99.34 mg/100 g for two Sudanese date palms. chemical properties of dates vary depending on various factors such as cultivars, region, climate and fertilizer20. The color measurement of Siwi and Sakkoti date fruits these results agreed with those found by Mohamed et al.22 and Hasnaoui et al.23 who reported that L value ranged from 12.12 to 38.93, a value in the range of +1.35 to+15.29 and b value in the range of +0.86 to +35.12. Measuring the color of date fruits is useful in comparing different dates. Overall, the difference in color is mainly due to genetic variability24. The values of H and C indicated the yellow color of date fruits12,13.

Almost all food-processing techniques and particularly fruits drying involve the use or the modification of water in food. The control of water activity in foods is an important tool for extending their shelf life. It protects the quality of foods by controlling microbial, chemical and physical changes. The moisture contents of Siwi and Sakkoti date fruits were agreement with Hussain et al.25 who found minimum moisture reduction (13.91%) and maximum moisture reduction (24. 13%). The results were in agreement with Ashraf et al.26 who reported that the increase in drying temperature and decrease in sample thickness significantly reduced drying time.

Table 10: Mean values of color whole dried Siwi and Sakkoti dates

Moisture content and drying rate were influenced by the drying temperature and sample size. The results shown moisture content was affected by temperatures and fruit surface transpiration. The effects of pretreatments and drying temperatures on pH value and acidity of Siwi and Sakkoti date fruits were in agreement with Nezam El-Din and Abd El-Hameed19 and Anet and Reynolds27 who reported a little decrease in pH value in sulfur treated date which may be resulted from the effect of sulfur dioxide on inhibition of non-enzymatic browning reaction. Total acidity of all treatments were more than that of the control date fruits which related to browning reaction Nezam El-Din28 and Mortazavi et al.29 who showed that reduction in acidity level by heating can be due to the conversion of part of organic acids into sugars, the relationship between the enzymatic acidity in date fruits and the pH value and color30. The total phenols of Siwi and Sakkoti date fruits shown were in agreement with those of Mansouri et al.31 who reported that phenols increased by drying. The significant increase in phenolic content on drying possibly due to degradation of tannins and maturation of degradative enzymes at a higher temperature, all treatments showed higher values of phenols content than the control32. Health benefit is an important attribute which enhance the quality of dried products. These results agreed with Mechlouch et al.33. Total sugars and non-reducing sugars decreased with increasing drying temperature and whereas reducing sugars increased by increasing drying temperature26. The reducing sugars represented 95.08% of the total sugars at tamer stage; this could be due to the effect of the inverses activity on the non-reducing sugars during ripening34.

Measuring color of whole date fruits is useful for the comparison among different pretreatments and the effects of drying temperature on the quality of dried dates. The high (L) value shows high degree of lightness of color. Statistical analysis showed significant differences (p<0.05) among means of color values of Siwi and Sakkoti cultivars the higher (L and b) values for the pretreatment with sulfur dioxide or sodium metabisulfite solution regardless increasing temperature. While, the color value of date observed in Siwi and Sakkoti cultivars, the lowest (a) values of the pretreatment with sulfur dioxide or sodium metabisulfite solution regardless increasing temperature. Color of pretreated were in agreement with Hasnaoui et al.23 and Biglari et al.24 evaluated the fruit color of date palm cultivars from Moroccan oases at tamer stage . The high color of (C) showed that near to yellow of dates. Hunter color (C) value was shown the intensity of color, Siwi and Sakkoti cultivars showed the highest (C) value 36.01 and 44.74 for pretreatment with sulfur dioxide dried at 60°C. Color (H) value of Siwi date was no significant sulfur dioxide or sodium metabisulfite solution at same temperature. On the other hand, the color (H) of pretreatments with sulfur dioxide or sodium metabisulfite solution were high score compared other treatments. In general, the difference in color mainly due to the pretreatments, drying temperature and the best treatments were sulfur dioxide or sodium metabisulfite solution with 60°C. The study recommends pretreated with sodium metabisulfite solution or sulfur dioxide before drying to improve color dried date products.

CONCLUSION

Date varieties (Siwi and Sakkoti) at the khalal stage of maturity can be successfully dried to produce high quality of semi-dry date products (whole, halves or pieces fruits) with pretreatments sodium metabisulfite solution or sulfur dioxide, then dried at 60°C.

SIGNIFICANCE STATEMENT

This study discovers the effect of pretreatments and different temperatures of date fruits Siwi and Sakkoti that can be beneficial for manufacturers to apply it on large scale. This study will help the researcher to cover the critical areas of the best pretreatment and temperature to obtain the best quality of date fruits that many researchers were not able to explore. Thus a new theory on these pretreatments materials and possibly other drying temperatures may be used in date industries.

ACKNOWLEDGMENT

The authors wished to thank Food Technology Research Institute, Agricultural Research Center for providing the necessary laboratory facilities.

REFERENCES
1:  Ahmed, I.A., A.W.K. Ahmed and R.K. Robinson, 1995. Chemical composition of date varieties as influenced by the stage of ripening. Food Chem., 54: 305-309.
CrossRef  |  Direct Link  |  

2:  FAO., 2015. Statistical databases. Food and Agriculture Organization of the United Nations, Rome, Italy.

3:  Ministry of Agriculture and Land Reclamation, 2015. Annual bulletin for agricultural economy. Economy Affaires Section, Central Management for Agricultural Economy, Cairo, Egypt.

4:  Al-Shahib, W. and R.J. Marshall, 2003. The fruit of the date palm: Its possible use as the best food for the future? Int. J. Food. Sci. Nutr., 54: 247-259.
CrossRef  |  PubMed  |  Direct Link  |  

5:  El-Sharabasy, S.F. and R.M. Rizk, 2019. Atlas of Date Palm in Egypt. Food and Agriculture Organization of the United Nations, Cairo Egypt, ISBN-13: 9789251315996, Pages: 544.

6:  Al-Farsi, M., C. Alasalvar, A. Morris, M. Baron and F. Shahidi, 2005. Comparison of antioxidant activity, anthocyanins, carotenoids and phenolics of three native fresh and sun-dried date (Phoenix dactylifera L.) varieties grown in Oman. J. Agric. Food Chem., 53: 7592-7599.
CrossRef  |  Direct Link  |  

7:  Abiola, T., D.C. Dibie, O.J. Akinwale and O.A. Shomuyiwa, 2018. Assessment of the antidiabetic potential of the ethanolic extract of date palm (Phoenix dactylifera) seed in alloxan-induced diabetic rats. J. Diabetes Metab., Vol. 9. 10.4172/2155-6156.1000784

8:  Vega-Mercado, H., M.M. Gongora-Nieto and G.V. Barbosa-Canovas, 2001. Advances in dehydration of foods. J. Food Eng., 49: 271-289.
CrossRef  |  Direct Link  |  

9:  Nijhuis, H.H., H.M. Torringa, S. Muresan, D. Yuksel, C. Leguijt and W. Kleok, 1998. Approaches to improving the quality of dried fruit and vegetables. Trends Food Sci. Technol., 9: 13-20.
CrossRef  |  Direct Link  |  

10:  Degefa, B.A., S. Muhammad and E. Fathelrahman, 2017. Market acceptability of dried dates at the unripe “Bisr” stage in United Arab Emirates. Emirates J. Food Agric., 29: 674-684.
CrossRef  |  Direct Link  |  

11:  Barbagallo, R.N., M. Chisari and G. Caputa, 2012. Effects of calcium citrate and ascorbate as inhibitors of browning and softening in minimally processed 'Birgah' eggplants. Postharvest Biol. Technol., 73: 107-114.
CrossRef  |  Direct Link  |  

12:  Hunter, R.S., 1942. Photoelectric tristimulus colorimetry with three filters. NBS Circular C 249, U.S. Department Commerce, Washington, DC., USA.

13:  Little, A.C., 1975. A research note off on a tangent. J. Food Sci., 40: 410-411.
CrossRef  |  Direct Link  |  

14:  AOAC., 2005. Official Methods of Analysis. 18th Edn., Association of Official Analytical Chemists, Washington, DC., USA.

15:  Makkar, H.P.S., M. Blummel, N.K. Borowy and K. Becker, 1993. Gravimetric determination of tannins and their correlations with chemical and protein precipitation methods. J. Sci. Food Agric., 61: 161-165.
CrossRef  |  Direct Link  |  

16:  Wolfe, K., X. Wu and R.H. Liu, 2003. Antioxidant activity of apple peels. J. Agric. Food Chem., 51: 609-614.
CrossRef  |  Direct Link  |  

17:  SPSS., 1990. SPSS/PC for the IBM PC/XI. SPSS Inc., Chicago, IL., USA.

18:  Zaitoon, A.M., A.M. Elansari, Y.S. Ahmed and N.A. Taha, 2016. Phase transitions of samani date palm (Phoenix dactylifera L.) fruit using Differential Scanning Calorimeter (DSC). Emirates J. Food Agric., 28: 625-632.
CrossRef  |  Direct Link  |  

19:  Nezam El-Din, A.E.M.M.M. and A.K.E.D. Abd El-Hameed, 2001. Study on the storage of Egyptian Siwi date variety (semi-dry date). Egypt. J. Agric. Res., 79: 1485-1498.

20:  Al-Hooti, S., J.S. Sidhu, J. Al-Otaibi, H. Al-Ameeri and H. Qabazard, 1997. Processing of some important date cultivars grown in United Arab Emirates into chutney and date relish. J. Food Process. Preserv., 21: 55-68.
CrossRef  |  Direct Link  |  

21:  Al-Farsi, M.A. and C.Y. Lee, 2008. Nutritional and functional properties of dates: A review. Crit. Rev. Food Sci. Nutr., 48: 877-887.
CrossRef  |  Direct Link  |  

22:  Mohamed, R.M.A., A.S.M. Fageer, M.M. Eltayeb and I.A.M. Ahmed, 2014. Chemical composition, antioxidant capacity and mineral extractability of Sudanese date palm (Phoenix dactylifera L.) fruits. Food Sci. Nutr., 2: 478-489.
CrossRef  |  Direct Link  |  

23:  Hasnaoui, A., M.A. Elhoumaizi, A. Asehraou, M. Sindic, C. Deroanne and A. Hakkou, 2010. Chemical composition and microbial quality of dates grown in Figuig oasis of Morocco. Int. J. Agric. Biol., 12: 311-314.
Direct Link  |  

24:  Biglari, F., A.F.M. AlKarkhi and A.M. Easa, 2008. Antioxidant activity and phenolic content of various date palm (Phoenix dactylifera) fruits from Iran. Food Chem., 107: 1636-1641.
CrossRef  |  Direct Link  |  

25:  Hussain, I., S. Ahmad, M. Amjad and R. Ahmed, 2014. Effect of modified sun drying techniques on fruit quality characters of dates harvested at rutab stage. J. Agric. Res., 52: 415-423.
Direct Link  |  

26:  Ashraf, Z., Z. Hamidi-Esfahani and M.A. Sahari, 2012. Evaluation and characterization of vacuum drying of date paste. J. Agric. Sci. Technol., 14: 565-575.
Direct Link  |  

27:  Anet, E.F.L.J. and T.M. Reynolds, 1957. Chemistry of non-enzymic browning. II. Reactions between amino acids, organic acids and sugars in freeze-dried apricots and peaches. Aust. J. Chem., 10: 182-192.
CrossRef  |  Direct Link  |  

28:  Nezam El-Din, A.M.M., 1978. Studies of the effect of browning reaction on the quality of dehydrated food. M.Sc. Thesis, Faculty of Agriculture, Al-Azhar University, Cairo, Egypt.

29:  Mortazavi, S.M.H., F. Azizollahi and N. Moallemi, 2015. Some quality attributes and biochemical properties of nine Iranian date (Phoenix dactylifera L.) cultivars at different stages of fruit development. Int. J. Hortic. Sci. Technol., 2: 161-171.
CrossRef  |  Direct Link  |  

30:  Benjamin, N.D., M.S. Al-Khalidi, H.R. Shabana and A.S. Moroki, 1985. The effect of cold storage conditions on the quality of six date fruit cultivars at Rutab stage. Date Palm J., 4: 1-18.

31:  Mansouri, A., G. Embarek, E. Kokkalou and P. Kefalas, 2005. Phenolic profile and antioxidant activity of the Algerian ripe date palm fruit (Phoenix dactylifera). Food Chem., 89: 411-420.
CrossRef  |  Direct Link  |  

32:  Maillard, M.N. and C. Berset, 1995. Evolution of antioxidant activity during kilning: Role of insoluble bound phenolic acids of barley and malt. J. Agric. Food Chem., 43: 1789-1793.
CrossRef  |  Direct Link  |  

33:  Mechlouch, R.F., A.A.G. Thabet, E.O. Elakesh and H.H.W. Elfalleh, 2015. Changes in the physico-chemical properties of palm date using different drying methods. University de Gabes Tunisie Bull., 17: 59-78.
Direct Link  |  

34:  Ramadan, B.R., M.N.A. El-Rify, A.A. Abd El-Hamid and M.H. Abd El-Majeed, 2016. Effect of some treatments on chemical composition and quality properties of Saidy date fruit (Phoenix dactylifera L.) during storage. Assiut J. Agric. Sci., 47: 107-124.
Direct Link  |  

©  2021 Science Alert. All Rights Reserved