Ashwini* and Nikhita Desai
AICRP on EAAI (Bioconversion Technology), Main Agriculture Research Station, University of Agricultural Sciences, Dharwad-580 005, Karnataka, India.
ABSTRACT
An investigation was undertaken to study effect of medicinal plant extracts/bulb extracts viz bael (50 and 70%), tulsi (50 and 100%), Garlic (5 and 10%) on shelf life of guava. The Physiological loss of weight in guava fruits showed an increasing trend in all the treatments. Contrary to this acidity decreased with storage. However, there was an increase in pH with extension of storage period. The total soluble solids of fruits first increased upto a certain period and there after decreased .Bulb extracts of garlic @ 10 per cent were most effective of all the treatments with minimum spoilage percentage followed by garlic extracts @ 5 per cent concentration and tulsi extracts at 100 per cent concentration. In the present study bael extracts (50 and 100 per cent concentrations) were not effective in extending the shelf life guava (Cv Allahabad Safeda).The investigation concludes that the shelf life of guava fruits Cv Allahabad Safeda can be extended from 4 to 7 days by treating the fruits with 10 per cent garlic extract.
Keywords: Guava fruits, Tulsi ,Garlic ,Bael extract.
INTRODUCTION
Guava (Psidium guajava L.), is one of the most important fruit crops in the world, belonging to the family Myrtaceae, also commonly known as poor man’s Apple due to its low price and it is also a most of the legendary fruits due to its hardy and prolific bearing nature1. Fruits are the source for human health they are rich in carbohydrates, vitamins and minerals with sweet taste, aroma and nutritive value. Fruits are poor in protein content with high level water quantity and the pH ranges from 7 to slightly acidic, these characteristics make a good platform for the growth of various microorganisms such as bacteria, molds and yeasts2.
Plants are the richest resource of drugs of traditional systems of medicine, modern medicines, nutraceuticals, food supplements, folk medicines, pharmaceutical intermediates and chemical entities for synthetic drugs. The major part of traditional therapy involves the use of plant extract and their active constituents3.
Guava fruits are severely affected by wilt disease leading to substantial loss in the crop production. Fusarium solani is the most predominant pathogen causing wilt of guava. To control these pathogens, chemical or synthetic compounds were used, it resulted in environmental contamination as chemical compounds are non-degradable in nature, causes side effects on beneficial organisms of the earth, stays on earth for very long duration and developed new physiological races in the pathogens4. These situations lead to the finding of alternative way for biopreservation, where the biologically synthesized chemicals are used which are ecofriendly and easily degradable. There is a widespread belief that green medicines are healthier and more harmless or safer than synthetic ones Medicinal plants have been used to cure a number of diseases. Though the recovery is slow, the therapeutic use of medicinal plant is becoming popular because of its inability to cause side effects and antibiotic resistant microorganisms5.
In the present study, biopreservation of guava fruits by using different concentration of Bael extract, garlic extract and tulsi extract was carried out in vivo to evaluate the effect of plant extract on preserving the guava fruits.
MATERIALS AND METHODS
LifeStudies of Guava Fruits
Matured, uniform sized, undamaged healthy fruits guava (Cv Allahabad safeda) were randomly selected after harvest and subjected to various treatments. There were seven treatments and three replications in each treatment. Aqueous extracts of efficient medicinal plants leaf/bulb extracts as obtained from screening for their antimicrobial properties in vitro from our previous studies were used.
The post harvest treatments imposed were as follows:
TREATMENTS |
|
T1 |
CONTROL |
T2 |
BAEL EXTRACT @50% |
T3 |
BAEL EXTRACT @75% |
T4 |
GARLIC EXTRACT @5% |
T5 |
GARLIC EXTRACT @10% |
T6 |
TULSI EXTRACT @50% |
T7 |
TULSI EXTRACT @100% |
Method of treatment
The fruits were dipped in the extracts for five minutes and then air dried. The untreated and treated fruits were bagged in new ventilated polythene covers and kept at room temperature. Observations were taken on the 3 rd,6th ,9 th and 12th day for guava.
Observations recorded
The observations recorded for shelf life studies were:
Spoilage Per Cent
The number of spoiled fruits were counted in each treatment. They were expressed as per cent of spoiled fruits.
Spoilage per cent = Number of fruits spoiled x 100
Total number of fruits
Physiological Loss of Weight (PLW)
The fruits were weighed at regular intervals i.e, on the 3 rd,6th ,9 th and 12th day after treatment for guava. The loss in weight of fruits due to spoilage was calculated as per cent loss of weight.
Titrable Acidity (Citric Acid %)
Total titrable acidity was determined by the method, described by Ranganna (1977)6. Five g of pulp was blended with 40 ml water and volume was made upto 50ml with distilled water. Five ml of this was taken and titrated against 0.1N NaOH solution using phenolphthalein. The acidity was expressed as citric acid per cent.
Total Soluble Solids (TSS)
Pulp from randomly selected fruit was taken and macerated for juice extraction and TSS of the juice was determined using hand refractrometer (Erma Japan) of 0-30 per cent range. The values were expressed as per cent total soluble solids of the fruits.
pH
Fifty grams of the pulp were macerated with fifty ml of distilled water. The pH was read using a Digital (Hanna) pH metre6.
Statistical Analysis
The data was statistically analyzed by adopting the analysis of variance technique appropriate to the levels of treatment 7.
RESULTS AND DISCUSSION
Shelf Life Studies of Guava
There was no significant difference between treatments on the 6th day (Table 1). Fruits treated with bael extracts @ 50 per cent concentration had a mean spoilage percentage of 6.67 as compared to that of control which had a mean spoilage percentage of 13.3 per cent . The fruits subjected to the rest of the treatments still remained healthy with no disease symptoms. There was significant difference among treatments on the 9th day after treatment. The fruits treated with garlic @ 10 per cent differed significantly with fruits treated with bael extracts @ 100 per cent which had a mean spoilage percentage of 53.33 per cent .
Table 1: Post Harvest shelf life of guava fruits treated with medicinal plant extracts
| Treatment | Spoilage days after harvest | |||
| 3 Days | 6 Days | 9 Days | 12 Days | |
| T1 Control | 0.00
(12.92) |
13.33
(21.39) |
80.00
(63.44) |
100.00
(93.24) |
| T2 Bael Extract @50% | 0.00
(12.92) |
6.67
(14.89) |
60.00
(50.77) |
100.00
(93.24) |
| T3Bael extract @75% | 0.00
(12.92) |
0.00
(12.92) |
53.33
(46.89) |
100.00
(93.24) |
| T4 Garlic extract @5% | 0.00
(12.92) |
0.00
(12.92) |
40.00
(39.23) |
86.67
(68.53) |
| T5 Garlic extract 10% | 0.00
(12.92) |
0.00
(12.92) |
26.67
(31.05) |
66.67
(54.70) |
| T6 Tulsi Extract 50% | 0.00
(12.92) |
0.00
(12.92) |
46.67
(43.05) |
93.33
(75.00) |
| T7 Tulsi Extract 100% | 0.00
(12.92) |
0.00
(12.92) |
33.33
(35.24) |
66.67
(54.70) |
| CD@5% | – | – | 15.73 | 15.61 |
Note: Spoilage is expressed as % of fruits spoiled
Figures in parenthesis indicate values after arc-sine transformation.
Spoilage percentage was up to 66.67 per cent with garlic (10 per cent) and tulsi (100 per cent) on 12th day of storage. Misra and Dixit (1976)8 reported that the extracts of garlic completely checked the growth of Pestalotia and Phomopsis. These two fungi cause severe post harvest losses in guava9. Srivastava and Bihari Lal (1997)10 stated that the leaf extracts of tulsi protected fruit rot of pear and pomegranate due to Alternaria alternata by 82 and 85 per cent respectively. Effective control of banana anthracnose was brought about by extracts of tulsi11.
The investigation was carried by G. S. Shinde et. al.12 2010 to study the retardation of ripening process and to minimize the post harvest losses in mango fruit under the influence of various plant extract treatments viz., neem leaf extract, bael leaf extract, neem oil and sesame oil.
Physiological loss of weight (PLW)
The PLW was measured at regular intervals upto 12 days after treatment. The treatments were on par with each other after 3 days(Table 2). There was no significant difference in physiological loss of weight in the fruits subjected to all the six treatments and control on the 6th day after treatment the fruits treated with tulsi extract at 50 per cent concentration showed maximum mean weight loss of 4.33 per cent. In rest of the treatment mean weight loss between 4.00 to 4.18 per cent. (Table 2).On 9th day all the treatments and control were on par with each other.
Significant differences were observed in physiological loss of weight on 12th day after treatment. The fruits treated with garlic extracts at 5 per cent and 10 per cent concentration showed minimum mean loss of weight of 24.35 per cent and 23.89 per cent respectively. They differed significantly from the other treatments. The rest of the treatments were on par with each other. Hittalmani (1986)13 reported that the decline in quality of stored fruits is due to build up of microbial populations.Similar results were obtained by Pandey et al. 198314 applied leaf extracts of Mentha and Melia to guava fruits and observed that these treatments were effective in retaining physical quality characteristics of fruits as they reduced moisture loss and storage rot symptoms.
Table 2: Post harvest physiological loss of weight (PLW) of guava fruits treated with medicinal plants extracts
| Treatment | PLW%- days after harvest | |||
| 3 Days | 6 Days | 9 Days | 12 Days | |
| T1 Control | 1.01
(5.74) |
4.07
(11.54) |
9.21
(17.66) |
12.72
(20.88) |
| T2 Bael Extract @50% | 1.00
(5.74) |
4.18
(11.68) |
7.49
(15.79) |
11.23
(19.55) |
| T3Bael extract @75% | 1.00
(5.74) |
4.04
(11.54) |
7.87
(16.22) |
10.05
(18.44) |
| T4 Garlic extract @5% | 1.00
(5.74) |
4.00
(11.54) |
7.00
(15.34) |
8.62
(17.05) |
| T5 Garlic extract 10% | 1.00
(5.74) |
4.00
(11.54) |
6.66
(24.89) |
8.05
(16.43) |
| T6 Tulsi Extract 50% | 1.11
(6.02) |
4.33
(11.97) |
7.26
(15.56) |
11.11
(19.46) |
| T7 Tulsi Extract 100% | 1.00
(5.74) |
4.15
()11.68 |
6.58
(14.77) |
9.98
(18.34) |
| CD@5% | – | – | – | 1.85 |
Note: Weight loss is expressed as % of weight loss
Figures in parenthesis indicate values after arc-sine transformation.
Titrable acidity
On day 3, there was not much difference in the acidity among the treatments (Table 3). On the 6th day, there was a decrease in acidity in all the treatments. After 9 days fruits dipped in garlic showed acidity of 0.46 percent. In rest of the treatments and control, the acidity was low ranging from 0.38 to 0.44 per cent. On day 12, there was a further decrease in acidity. Maximum acidity of 0.35 was recorded in fruits dipped with garlic extracts @ 5 per cent. In rest of the treatments, there was not much difference in the acidity percent.
These results are compatable with the several works of 15 16 17 18 .The decrease in acidity could be probably due to increased utilization of organic acids during respiration resulting in increased rate of ripening19.
Table 3: Post harvest changes in titrable acidity (citric acid %) of guava fruits treated with medicinal plants extracts
| Treatment | Titrable Acidity days after harvest | |||
| 3 Days | 6 Days | 9 Days | 12 Days | |
| T1 Control | 0.54 | 0.47 | 0.41 | 0.27 |
| T2 Bael Extract @50% | 0.52 | 0.46 | 0.39 | 0.29 |
| T3Bael extract @75% | 0.56 | 0.51 | 0.41 | 0.27 |
| T4 Garlic extract @5% | 0.55 | 0.52 | 0.46 | 0.35 |
| T5 Garlic extract 10% | 0.56 | 0.50 | 0.44 | 0.33 |
| T6 Tulsi Extract 50% | 0.54 | 0.46 | 0.38 | 0.26 |
| T7 Tulsi Extract 100% | 0.60 | 0.52 | 0.43 | 0.31 |
Note: Titrable Acidity expressed as citric acid %
Total soluble solids (TSS)
After 3 days of treatment, the TSS of fruits did not vary much (Table 4). It ranged from 7.6 to 8.2 per cent. An increase in TSS content of fruits was noticed in all the treatments and control after 6 days. Fruits treated with tulsi extracts (100 per cent concentration) recorded maximum TSS of 9.8 per cent .Lowest TSS (8.8 per cent) was observed in fruits treated with garlic extracts (5 per cent concentration). On 9 th day, the control fruits recorded lowest TSS (11.0 per cent) .However in all the treatments and control the TSS increased to its maximum. After 12 days of treatment, there was a decline in the TSS of fruits. The fruits treated with bael extracts (50 per cent) recorded minimum TSS of 9.6 per cent whereas the fruits dipped in garlic extracts maintained TSS at 10.4 per cent.
Fruits dipped in garlic (5 and 10 per cent) and tulsi (50 and 100 per cent) maintained the TSS throughout the period .However, the control fruits and fruits dipped in bael extract (50 and 75 per cent) recorded low TSS value throughout the assessment period. Aspergillus flavus and Aspergillus parasiticus infected guava fruits showed a considerable loss in total, reducing and non reducing sugars20. Fungi are capable of synthesizing many of their requirements if simple sources of nutrient are available.
Table 4: Post Harvest changes in total soluble solids (TSS) of guava fruits treated with medicinal plants extracts
| Treatment | Total soluble solids days after harvest | |||
| 3 Days | 6 Days | 9 Days | 12 Days | |
| T1 Control | 8.0 | 9.4 | 11.0 | 9.8 |
| T2 Bael Extract @50% | 8.2 | 9.2 | 11.4 | 9.6 |
| T3Bael extract @75% | 7.8 | 9.0 | 11.2 | 10.0 |
| T4 Garlic extract @5% | 7.6 | 8.8 | 11.6 | 10.2 |
| T5 Garlic extract 10% | 8.0 | 9.6 | 11.4 | 10.4 |
| T6 Tulsi Extract 50% | 8.0 | 9.4 | 11.6 | 10.0 |
| T7 Tulsi Extract 100% | 8.2 | 9.8 | 11.4 | 10.2 |
Note: The values are expressed as per cent total soluble solids of the fruits
pH
The pH was recorded at different intervals for a period of 12 days (Table 5). On day 3, there was not much variation in the pH content among the treatments. On day 6 there was slight increase in pH among all treatments. Fruits treated with bael extracts @ 50 per cent concentration showed a maximum pH of 4.4, followed by fruits treated with tulsi extracts @ 100 per cent concentration (4.2). In rest of the treatments and control the pH (4.1) remained same. At 12 days after treatment, there was further increase in pH among all the treatments and control.
After 12 days of treatment, there was an increase in pH value of guava fruits. There was gradual increase in pH of fruits treated with bael extracts (75 per cent concentration) followed by bael extract (50 per cent) treated fruits. The mature guava fruits had a pH of around 5.0 which is suitable for the production of pectinolytic enzymes by Gleosporium psidii the causal organism of fruit rot of guava.
Table 5: Post-Harvest changes in pH of guava fruits treated with medicinal plants extracts
| Treatment | pH-Days after harvest | |||
| 3 Days | 6 Days | 9 Days | 12 Days | |
| T1 Control | 3.9 | 4.1 | 4.4 | 4.9 |
| T2 Bael Extract @50% | 3.8 | 4.4 | 4.5 | 5.0 |
| T3Bael extract @75% | 4.0 | 4.1 | 4.3 | 5.1 |
| T4 Garlic extract @5% | 3.9 | 4.1 | 4.1 | 4.7 |
| T5 Garlic extract 10% | 3.8 | 4.1 | 4.3 | 4.8 |
| T6 Tulsi Extract 50% | 3.9 | 4.1 | 4.2 | 4.7 |
| T7 Tulsi Extract 100% | 4.1 | 4.2 | 4.2 | 4.9 |
Conclusions
The investigation concludes that the shelf life of guava fruits Cv Allahabad Safeda can be extended from 4 to 7 days by treating the fruits with 10 per cent garlic extract.
Acknowledgements
The authors gratefully thank UAS, Bangalore for the support
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