New Technology

RECENT ADVANCES IN POST HARVEST TECHNOLOGY OF

VEGETABLES AND FRUITS IN PAKISTAN  

1.             ABSTRACT

                  In Pakistan the magnitude of post harvest losses of vegetables and fruits is about 35%. Efforts are being made both at federal and provincial level to minimize these losses to safe guard the interest of growers, processors, traders, retailers and consumers. However, the primary objective of research and development activities on post harvest handling and quality preservation of vegetables and fruits being carried out in the country is our national food security and to promote export of these high value commodities to other countries. The recent advances made in the area of post harvest technology and research in Pakistan are discussed in this paper. 

2.             INTRODUCTION

                   Agro-climatic conditions of Pakistan ranging from tropical to temperate allow growing 40 different kinds of vegetables and 21 types of fruits (Raja, M.B. and K.M. Khokhar, 1993). Major vegetables grown in Pakistan include potato, onion, chilli, melons, cucurbits, tomato, turnip, okra and pea, whereas citrus, dates, mango, guava, apple, banana, apricot, grapes, almonds, peach, plum and pomegranate are the main fruit crops. At present area under fruits and vegetables is 0.995 million ha (4.3% of the total cropped area) with the total production of 10.992 million tonnes (Government of Pakistan, 1999). Area and production both increased in the past but at a very low pace. The major factor limiting increase in area and production remained high investment and low return to the growers. Postharvest losses in fruits and vegetables range from 25-40% (Raja, M.B. and K.M. Khokhar, 1993) or even qreater (Iqbal, M., 1996). Consumers prices rise in addition to hidden quality losses. These losses bring low return to growers, processors and traders and country also suffers in terms of foreign exchange earning. In fruits and vegetables the quality of produce starts deteriorating right after their harvest. Primary factors responsible for post‑harvest produce losses are: poor pre‑harvest measures-- adoption of poor production techniques (varieties with low shelf life, imbalance use of nutrients, insect pest and disease infestation and abiotic stresses; low tech harvesting procedures-- non‑application of pre‑harvest recommended treatments/practices, harvesting at improper stage and improper care at harvest; and post‑harvest problems-‑ non‑removal of field heat, dumping produce, moisture condensation causing pathogen infestation, packaging in bulck with out sorting and grading of produce, improper transportation and storage, and distant and time consuming market distribution (Kader, A.A., 1992). In order to preserve the produce quality different post-harvest techniques are recommended for variety of produce. These techniques include; hydrocooling, refrigeration & freezing, modified atmosphere (MA) packaging, MA storage,  control atmosphere storage, skin coating, hypobaric or low pressure storage, irradiation, dehydration, canning, high pressure processing and pulsed electric fields and pulsed light applications. In order to promote horticultural industry in Pakistan, standardization of pre-harvest and post-harvest management technologies minimizing postharvest losses and to enhance foreign exchange earning to the maximum extent are therefore essentially required for necessary adoption. At present various R&D institutions are working on different aspects of postharvest management of vegetables and fruits.

3.             RESEARCH INFRASTRUCTURE

                Information on institutions and their involvement in postharvest handling, dehydration, processing and  preservation of fruits and vegetable work is given in Table-1.

  Table-1:  Institutions involve in postharvest research work on vegetables and fruits.

                  For proper redressal of the key issues a well coordinated research and development programme at national level is however lacking.

  4.             ADVANCES IN POSTHARVEST TECHNOLOGY AND RESEARCH

                  Information on recent advances made in postharvest technology and research at various institutions in Pakistan (also include as given under references) is summarized below.

  4.1 Selection of varieties for better shelf life

                 Vegetable varieties: Riogrande, Roma AVRDC Cv. (tomato), NARC ‑ 91 (onion), Medium Long Green (chillies), Local Selections (cucumber) and VIP (pea) have shown better transportation quality and longer shelf life. In fruits; varieties: Begum Jangi (date palm), Cardinal, Flame Seedless (grapes), Local Selections (fig), Sultan (pomegranate) and ARS (N) Mingora No. 7, No. 8 & No. 9 (peach) were found high yielding with longer post‑harvest life.

  4.2 Influence of rootstocks on postharvest quality of some apples 

                Studies carried out at Deciduous Fruit Development Centre, Sariab, Quetta revealed that on rootstock MM 106, apple cultivars (Red Delicious, Golden Delicious, Star King Delicious and Spartan) showed better performance than on M‑9 rootstock for fruit texture and soluble solids. On the basis of organoleptic evaluation or consumers' acceptability' MM‑106 showed partially better performance than M‑9. For skin colour of fruit, rootstock M‑9 showed better results over MM‑106. However, rootstock MM-106 should better performance in terms of fruits texture, total soluble solid contents and consumers' acceptability over M-9 rootstock.

  4.3 Pre-harvest application of fungicides

               Pre-harvest application of Benlate 50 WP minimized mold growth and increased shelf life of citrus (Kinnow Mandrin) at ambient storage temperature.

4.4 Pre-harvest application of growth hormone

                GA3 when applied @ 20 ppm on grape Cv. "Kishmish" not only increased the berry size, yield, protein, reducing & non‑reducing sugars, pectin and ascorbic acid but also, the mineral contents of berries (sodium, calcium magnesium and iron contents) were increased hence improved the quality of fruits and also its postharvest longevity.

4.5 Postharvest application of calcium chloride

                  Freshly harvested tomato fruits of variety" Nagina" when dipped in 4% CaCl2 solution and kept at 15oC maintained marketable quality upto 16 days. 

4.6 Studies on degreening of citrus and mango

                   Studies on degreening of citrus and mango showed that citrus variety "Salustiana" stored at 30oC and 85‑90% RH (controlled atmosphere) developed uniform colour after  24 hours, whereas in case of variety "Honey Mandrine" there was a slight colour development even after 36 hours. In case of mango variety "Chaunsa" stored at 17oC and 80‑85% RH after chilling resulted uniform colour development and produced natural flesh taste.

  4.7 Studies on wax coating materials

                   Wax coating studies are being carried out to make the produce more attractive with better shelf life. Carnauba based surface wax increased shelf life of Kinnow 3‑4 weeks by delaying senescence. Edible film coatings with gelatin (4%), corn starch (3%), HPMC (3%) and stearic acid (1.5 to 3%) composition enhanced storage life of carrots variety, "T‑29" upto 45 days with minimum (10‑15%) post‑harvest water loss. 

4.8 Studies on potato storage

                   Autumn potato crop is the main crop grown in the plains of Punjab. The crop is harvested during the month of January. The produce is kept in the field until the end of February because of low temperature. Thereafter, potatoes are mostly stored in the field in ordinary storage structures, where weight loss, rotting and sprouting of tubers deteriorate the quality of produce. In cold storage the produce is held at 4-5oC. At this temperature starch is converted to sugar and therefore potatoes become sweet. Also, because of high charges of electricity this costs much higher as compared to ordinary storage conditions or storage of potatoes at relatively higher temperature. Studies associated with these problems reveal that:

1.         Improved low cost on-farm storage structure (where hot air is replaced by cool air during night using electric fan) the inside temperature was observed 3-4oC low and the stored potatoes retained marketable quality upto 90 days.

2.         The sprout suppressant, "Camptothecin" when applied (sprayed)  @ 0.5 mM inhibited sprouting of  tubers upto 45 days at 39oC, whereas in untreated control sprouting started after 30 days at 39oC.

3.         The sprout suppressants CIPC @ 1500 ppm and 2000 ppm, IPC @ 1500 IPM and 2000 ppm and DECCO - 276E (combination of CIPC and IPC) @ 4.4 ml/100 ml water spray checked weight loss, sprouting and sweetening when potatoes were held at 5oC and 9oC storage temperatures and 90% RH until 105 days.

4.        Quality of potato tubers when held at 5oC or 9oC and 90% RH was retained until 60 days as the weight loss, rotting, sprouting and sweetening were checked.

  4.9 Studies on date palm storage

       Results on date palm post‑harvest storage indicated that ‑3oC was the optimum storage temperature for variety "Dakki". After one month of storage T.S.S. increased from 38.5% to 42.0% with 38.6% weight loss

  4.10 Studies on tomato fruit storage

      In case of  tomato, variety "Nagina" when dipped in 4% CaCl2 solution and kept at 15oC maintained marketable quality upto 16 days.

  4.11 Studies on olive preservation

      Olive fruit when preserved using 15% NaCl solution was found successful.

4.12 Quality preservation of apricots

    Apricots when dipped @ 3% solution of potassium meta bisulphite for 3 hours and then dried proved to be         successful.

4.13 Radiation effects on extending shelf life of some fruits and vegetables

      Nuclear Institute for Food and Agriculture (NIFA), Peshawar demonstrated inhibitory effects on sprouting of onions and  potatoes during storage; delay in ripening in banana, guava, mangoes, pears, tomatoes and persimmon; rot control in oranges and improvement in quality of mature green peaches by using safe levels of Gama radiations.

  5. SUMMARY

           Selection of varieties according to the market requirement coupled with improved production practices would ensure minimum wastage after harvest. For country like Pakistan low cost, economically feasible technology such as on-farm low cost storage (structures) hydrocooling, MAP, CA storage and waxing/skin coatings seems to be appropriate. Sorting and grading are pre-requisite for appropriate packaging and market distribution. Low cost energy efficient on‑farm storage structures are to be introduced on extensive scale. Packaging has to be cost effective. Dehydration of vegetables and fruits is to be introduced as cottage industry. Preservation and processing of vegetables and fruits both at semi- commercial and commercial scale needs to be carried out. The aforementioned items would ensure optimum return to growers and traders. Better produce handling and management would ensure regular market supply and the consumers will enjoy the affordable prices. This will also help promoting export of high value perishable commodities to other countries. A well coordinated R&D programme on produce handling and marketing at national level is, therefore, essentially required.

  6. REFERENCES

1. Ayub Agricultural Research Institute. 1998. Annual Research Programme Meeting of Horticulture Research Institute, Vegetable Research Institute, Postharvest Technology Centre and Food Technology Section, 08 October 1998, Faisalabad.

2. Government of Pakistan. 1999. Agricultural Statistics of Pakistan Ministry of Food, Agriculture & Livestock. Economic Wing, Islamabad.

3.  Iqbal, M. 1996. Type and extent of postharvest losses in horticultural commodities on Pakistan (pp:33-42). In: Proceedings of national conference on postharvest technology of horticulture commodities, 10-12 September, 1996, Quetta.

4. Kader, A.A. 1992. Postharvest Tec hnology of Horticultural Crops. Second Edn. University of California, Division of Agriculture and National Resources. Publication 3311.

5. Nuclear Institute for Food and Agriculture. 1996. Annual Report, NIFA, Peshawar.
6. Raja, M.B and K.M Khokhar. 1993. Postharvest horticulture technology and its future prospects (pp:265-277). In: proceeding of first international horticulture seminar, 09-11 January 1992. Pakistan Agricultural Research Council, Islamabad.

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