RESULTS AND DISCUSSIONS:
Weight Loss (%):
The highest weight loss was recorded in T4 (2ml/1L) followed by T1 (control) while the lowest occurred in fruits treated with 0.5ml/L thyme oil i-e T2 (Table 1). A consistent increase in weight loss was observed in all the treatments throughout the storage period
(Fig.1).
Thus, the results of this study suggest that thyme essential oil might have reduced respiration and transpiration rates which in turn delayed senescence in peach fruits.
Sellamuthu et al. (2013) concluded that weight loss in thyme oil treated avocados was significantly lower comparable to control ones.
TREATMENTS
STORAGE INTERVAL
- DAY 7
- DAY 14
- DAY 21
- DAY 28
- T1 3.20 4.93 7.85 12.29
- T2 2.80 5.54 8.16 11.06
- T3 3.73 6.05 8.96 11.84
- T4 3.11 9.13 18.48 18.70
Titratable Acidity:
A decrease in the titratable acidity was found for T3 (1ml/L) and T4 (2ml/L), which gradually dropped from 0.44 and 0.68 to 0.38 and 0.58. T1 (control) and T2 (0.5ml/L) retained higher content of TA i-e. 0.66 and 0.55, during the entire storage period.
It is matter of fact that fruit taste is determined by the sugar to acid ratio.
It has been proposed that TA decreases in fruits as a result of conversion of acids to sugars during respiration (Burmeister et al., 1997). A decrease in the TA values of peach fruits treated with hot water immersion has been observed by Amjad et al (2016).
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 0.22 0.59 0.42 0.54 0.66
- T2 0.44 0.63 0.41 0.48 0.55
- T3 0.44 0.64 0.55 0.46 0.38
- T4 0.68 0.58 0.73 0.65 0.58
Ascorbic Acid Content (Vit C):
All the treatments showed a gradual decrease in ascorbic acid level during the first week of storage period and a rapid increase in the next seven days.
T2 treated with 0.5ml/L thyme oil, maintained highest ascorbic acid content as compared to other treatments, for the rest of the storage period.
On the contrary, ascorbic acid content in T3 (1ml/L) and T4 (2ml/L) dropped rapidly in the last two weeks i-e 14 days.
91% of ascorbic acid in the human diet comes from fruits and vegetables. It is very sensitive to degradation due to its oxidation as compared to other nutrients during storage and processing (Akhtar et al., 2010).
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 3.0 2.2 2.4 2.6 3.0
- T2 3.3 2.0 2.7 2.9 3.1
- T3 3.0 1.7 4.1 3.4 2.6
- T4 3.0 2.2 4.9 3.4 2.6
PH:
The pH of T2 (0.5ml/L) and T3 (1ml/L) increased from 3.75 and 3.67 to 4.10 and 3.73 while a linear decline was observed in the pH values of T1 (control) and T4 (2ml/L) during cold storage, with no signi?cant di?erence being observed between treatments. The highest value for pH was observed in T2 (4.10) and lowest value in T1 (3.28) followed by T4 (3.61).
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 3.66 3.71 3.98 3.78 3.28
- T2 3.75 3.76 3.83 3.89 4.10
- T3 3.67 3.63 3.75 3.87 3.73
- T4 3.65 3.85 3.17 4.18 3.61
Total Soluble Salts (TSS):
A general increase was observed in TSS of all treated peaches while the TSS of control peaches dropped from 6.53 to 3.02, during storage period of 28 days.
Among the thyme oil treated fruits, maximum TSS was recorded in T3 (1ml/L) followed by T4 (2ml/L) i-e. 5.87 and 5.03. A relatively low TSS was observed in fruits treated with 0.5ml/L thyme oil, whereas much lower values were noticed in control fruits.
The result accounts that thyme oil treatment significantly maintained higher TSS in a concentration dependent manner. Peach fruits are supposed to be sweeter i-e. higher TSS for consumer acceptability (Crisosto et al., 2003).
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 6.53 4.73 5.10 3.60 3.02
- T2 4.60 4.87 5.77 4.07 4.00
- T3 3.87 5.40 4.37 5.07 5.87
- T4 3.83 4.13 6.57 4.00 5.03
Fruit Firmness:
Fruit firmness is one of the most important quality attribute in determining the texture as well as the ripening progress in fruits. Thus, the effect of thyme essential oil on flesh firmness of peach fruits has been examined. Fruit firmness has been attributed as the function of compression and puncture.
During cold storage, fruit ?rmness decreased for both treated and controlled peaches. Maximum flesh firmness was recorded in T2 (0.5ml/L) followed by T1 (control) as compared with T3 (1ml/L). T4 treated with highest concentration of thyme essential oil i-e. 2ml/L displayed the highest softening rate during the period of 28 days.
Higher firmness in treated fruits might be assigned to the reduced hydrolysis of soluble starch.
The decline of flesh firmness in peach fruits during storage was observed by Fern?ndez-Trujillo and Artes (1997) and Serrano et al. (2004).
Compression:
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 33.56 18.22 10.43 19.00 13.67
- T2 31.42 19.49 16.43 22.04 15.77
- T3 27.70 30.96 28.05 16.12 12.09
- T4 49.10 23.17 11.96 20.76 9.90
Puncture:
TREATMENTS STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 5.27 2.64 2.27 4.61 2.00
- T2 6.84 3.17 1.91 2.60 2.77
- T3 7.21 3.60 5.90 2.31 2.02
- T4 12.55 2.96 2.75 4.43 2.03
Organoleptic Evaluation:
TREATMENTS
STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 9 8 8 7 6
- T2 8 8 7 7 6
- T3 8 7 6 6 5
- T4 7 6 5 5 4
% Decay Index:
(Palou et al., 2002)
TREATMENTS
STORAGE INTERVAL
DAY 1 DAY 7 DAY 14 DAY 21 DAY 28
- T1 0 22.22 55.56 77.78 100
- T2 0 11.11 11.11 22.22 33.33
- T3 0 0 0 11.11 22.22
- T4 0 22.22 33.33 55.56 66.67
REFERENCES:
AKHTAR, N., AHMAD, M., KHAN, H. M. S., AKRAM, J., GULFISHAN, G., MAHMOOD, A. & UZAIR, M. 2010. Formulation and characterization of a multiple emulsion containing 1% L-ascorbic acid. Bulletin of the Chemical Society of Ethiopia, 24.
BURMEISTER, D. M., BALL, S., GREEN, S. & WOOLF, A. B. 1997. Interaction of hot water treatments and controlled atmosphere storage on quality ofFuyu’persimmons. Postharvest Biology and Technology, 12, 71-81.
CRISOSTO, C. H., CRISOSTO, G. & BOWERMAN, E. Understanding consumer acceptance of peach, nectarine and plum cultivars. International Conference on Quality in Chains. An Integrated View on Fruit and Vegetable Quality 604, 2003. 115-119.
FERN?NDEZ-TRUJILLO, J. P. & ARTES, F. 1997. Quality improvement of peaches by intermittent warming and modified-atmosphere packaging. Zeitschrift f?r Lebensmitteluntersuchung und-Forschung A, 205, 59-63.
PALOU, L., CRISOSTO, C. H., SMILANICK, J. L., ADASKAVEG, J. E. & ZOFFOLI, J. P. 2002. Effects of continuous 0.3 ppm ozone exposure on decay development and physiological responses of peaches and table grapes in cold storage. Postharvest biology and technology, 24, 39-48.
SELLAMUTHU, P. S., MAFUNE, M., SIVAKUMAR, D. & SOUNDY, P. 2013. Thyme oil vapour and modified atmosphere packaging reduce anthracnose incidence and maintain fruit quality in avocado. Journal of the Science of Food and Agriculture, 93, 3024-3031.
SERRANO, M., MART?NEZ?ROMERO, D., CASTILLO, S., GUILL?N, F. & VALERO, D. 2004. Effect of preharvest sprays containing calcium, magnesium and titanium on the quality of peaches and nectarines at harvest and during postharvest storage. Journal of the Science of Food and Agriculture, 84, 1270-1276.
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