de Laval, Qc, Canada H7N 429; 'OAEP, Vibhavadee Rangsit Road Bangkhen Bangkok. 10900 ... fresh storage life, while ensuring the quality of the mangoes. 273 ... AA is easily and reversibly oxidized to DHA, which is still the level of total ...
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EFFECT OF GAMMA IRRADIATION WITH OR WITHOUT HOT WATER DIP AND TRANSPORTATION FROM TRAILAND TO CANADA ON NUTRITIONAL QUALITIES, RIPENING INDEX AND SENSORIAL CHARACTERISTICS OF THAI MANGOES (NAHNG GLAHNG WAHN VARIETY)
Lacroix, M.'*, Gagnon, M.l, Pringsulaka, V.', Jobin, M.', Latreille, B.', Y.', Charoen, S.', Adulyatham, P.', Lettre, No chpramool, K.2, Prachasitthisak, J.'r'and Grad, B.' 'Canadian Irradiation Center, 535 Blvd Cartier, de Laval, Qc, Canada H7N 429; 'OAEP, Vibhavadee 10900, Thailand
C.P. 320, Succ. L-D-R, Ville Rangsit Road Bangkhen Bangkok
ABSTRACT Two lots of mangoes of the Nahng Glahng Wahn variety from Thailand were (TIC) at 0.49 to 0.77 kGy. irradiated at the Thai Irradiation Center Following this, one batch was retained in Thailand while the other was shipped of the same to the Canadian Irradiation Center (CIC) for investigation This way, it was hoped to compare the effects of variables during storage. (I) before and after gamma radiation with hot water dip (HWI) or without transportation on the ripening, vitamin C and vitamin A content and sensory The results indicate that the I and HWI treatments qualities of mangoes. The irradiated groups appeared to have delayed the ripening of the mangoes. a slightly higher content of ascorbic acid on the first day after irradiation than their corresponding controls. The sensory evaluation indicates that the panelists mostly favoured the I and HWI irradiated groups for the overall appearance and texture of whole mangoes and pulp and in taste and palatability Transportation stress did not appear to have much of an of the pulp alone. effect on the ascorbic acid and dehydroascorbic acid levels and the sensorial The mangoes stored and studied in Canada appeared to have a lower tests. vitamin A content.
KEY WORDS Mangoes;
irradiation;
nutritional
evaluation;
sensory
evaluation.
INTRODUCTION The commercial prospects for the mango industry in Thailand are very promising. to fully exploit the economic potential of this However, commodity, the most important pest and diseases which afflict the fruits must be efficiently dealth with, so that the time available is extended to cover the relatively large distances involved between the production site and the ultimate consumers. In order to control severe post-harvest losses of low dose (C 1 kGy) gamma irradiation has been recognized to be an mangoes, effective process in the disinfestation of fruit flies and seed weevils, the inactivation or reduction of spoilage microorganisms and the delay of ripening and senescence (Thomas and Sreenivasan, 1970). This project was initiated by Nordion International Inc. who contracted the Canadian Irradiation Center (CIC), the Research Center of Sciences Applied to Food (CRESALA) of the Institut Armand-Frappier and the Office of Atomic Energy for Peace (OAEP) to investigate the possibility of using ionizing radiation alone and in combination with a hot water dip treatment to achieve a longer fresh storage life, while ensuring the quality of the mangoes.
273
274
M. LACROIX et al. MATERIALS
Irradiation
and storase
AND METHODS of manaoes
Upon arrival at TIC, the mangoes (Nahng Glahng Wahn variety) were sorted to select only those in the uniformly mature green stage, free or color breaks, bruises or other quality defects. All radiation treatments were made in the JS-8900 carrier type irradiator equipped with a Co6' source. The minimum absorbed dose was 0.49 kGy and the maximum absorbed dose was 0.77 kGy for a mean dose of 0.63 kGy. 48 cartons each of unirradiated (control or C), irradiated (I) and hot-dipped plus irradiated (HWI) mangoes were shipped immediately to Montreal for delivery to CIC at day 7 where they were stored at 15'C and 60-65% R.H. Another 48 cartons in each of the C, I and HWI groups were kept at TIC where they were stored at 18'C and 65-75% relative humidity from day 1. I and HWI mangoes were divided into two groups with mean minimum and maximum absorbed doses of 0.56 kGy (I-) and 0.70 kGy (I+). Fricke dosimeters were placed strategically throughout the carrier during loading to validate the dose distribution throughout the cartons.
Rioenina
of manuoes
At TIC and CIC, the fruits were evaluated for ripening (surface color development) defined in 4 stages: stage 1. Mature green; stage 2. More green than yellow; stage 3. More yellow than green; stage 4. Fully ripe - all yellow.
Vitamin
A and C
The determination of ascorbic acid (AA) and dehydroascorbic acid (DHA) levels was carried out with a method described by the A.O.A.C., 12th edition, 1975 at TIC and by the method described by Boehringer Mannheim analysis kits at The determination of vitamin A was carried out by the method described CIC. in the AOAC (1990).
Sensorv
evaluation
At TIC and CIC the taste and palatability of pulp mangoes and the overall appearance, odor, and texture on whole and pulp mangoes were evaluated using a hedonic acceptability test (Larmond, 1979).
RESULTS Rioenina
AND DISCUSSION
of manaoes
The results of the ripening changes of mangoes showed that, at the TIC, the C samples were riped 100% within 20 days while I and HWI samples took 32 days At the CIC, at day 27, the C mangoes are completely to reach 100% ripening. in stage 4 while 66% of I and 47% of HWI treated mangoes are in stage 4 (Table delayed in I mangoes as 1). Development of ripe skin color was significantly compared to the C. The HWI treatment also showed a delayed ripening of about However, HWI 12 to 14 days as compared to the C in TIC and 10 days in CIC. was not significantly different from irradiation alone in this respect.
Vitamin
A and C
The changes in the content AA and DHA are shown in Figure 1 (TIC) and Figure 2 (CIC). The AA level of the mangoes peaked twice at the TIC (at day 8 and around days 15 to 18) while it peaked only once at the CIC (around days 7 to 12). The higher levels of AA in the C than in the I and HWI groups were more The DHA level of the apparent in the lot at CIC than in the lot at TIC. At CIC, mangoes had 2 peaks at TIC (at day 13 and around days 20 to 25). there was one peak which not only occurred later (around days 23 to 34) but there were no Moreover, reached much higher values than in the TIC lot. consistent differences in DHA between the C, I and HWI in lots at TIC and CIC. AA is easily and reversibly oxidized to DHA, which is still the level of total
8th International Meeting on RadiationProcessing vitamin C also decreases (Thomas, 1975). 1981) the low dose range (up to 1 kGy),
However, nutrient
27.5
according to (FAO/IAEA/WHO, losses are insignificant.
The effect of irradiation on vitamin A content is shown in table 2. In general, in both the TIC and CIC series the vitamin A content increased as the fruit ripened with differences due to treatment being more apparent at TIC. This difference is probably due to the delay in vitamin A synthesis in treated The most notable differences between TIC and CIC were the lower mangoes. This could be due to the stress of values in the latter than the former. The level of vitamin A content in transportation endured by the mangoes. mangoes is not affected greatly by low doses irradiation (Cuevas-Ruiz et al ., 1972).
Sensory
evaluation
The general trend in these hedonic tests was where there were significant differences in the overall appearance and texture of whole mango and pulp and in taste and palatability of the pulp between the various groups, they were mostly in favour of the I and HWI treated groups throughout the experiment. However, the odor of whole mangoes and pulp were not much affected by the The texture of whole and pulp irradiation treatments (Tables 3 and 4). mangoes was hard and disliked somewhat on the first day of sensory evaluation but became softer and more acceptable during storage with the ripening of the fruit. Moreover, when the fruit became overriped, as occurred earlier in the controls than in the I and HWI groups, the texture, the taste and palatability The appearance of black and brown spots, as then became unacceptable again. it occurred earlier in the control, was responsible for the decrease in the acceptability of the overall appearance of the mangoes. As observed by quality of HWI mangoes was found acceptable. Manalo, 1985, the organoleptic
CONCLUSION From both TIC and CIC experimental results, it is clear that irradiation alone or combined with a hot water dip, delayed the ripening of mangoes without affecting consumer acceptability and sensorial quality of mangoes.
REFERENCES AOAC Association of Official Analytical Chemists (1990). Official methods of analysis. 15Th edition. J. Agric. Univ. Puerto Cuevas-Ruiz, R.J., H.D. Graham and R.A. Luse (1972). Rico. 56: 26. FAO/IAEA/WHO (1981). Wholesomeness of irradiated food. Who technical report series 659. Larmond, E. (1979). Laboratory methods for sensory evaluation of food. Canada department of agriculture, Ottawa, publication 1637. Integrated studies of irradiated Philippine mangoes. Manalo, J.A. (1985). IAEA-R-2833-F. Osborne, D.R. and P. Voogt. (1978). The analysis of nutrients in foods. Academic press. (1970). J. Scient. Ind. Res. 29: 414. Thomas, P. and A. Sreenivasan.
8th International
WC 42-113-l
Meeting
on Radiation
Processing
