Effect of Stage of Ripening on Mechanical Damage in Tomato Fruits

Transcription

1 American-Eurasian J. Agric. & Environ. Sci., 9 (3): 97-3, 1 ISSN IDOSI Publications, 1 Effect of Stage of Ripening on Mechanical Damage in Tomato Fruits 1 Salamolah Mohammadi-Aylar, 1 Shahzad Jamaati-e-Somarin and Jafar Azimi 1 Islamic Azad University, Ardabil Branch, Ardabil, Iran Young Researchers Club, Islamic Azad University, Ardabil Branch, Ardabil, Iran Abstract: Mechanical damage is the major cause of postharvest losses and among the perishable crops tomato is susceptible to mechanical injury considrably. By conducting a series of impact tests (from.18 to.88 J) by a pendulum impact apparatus, occurance of damage, in the form of rupture and latent damage, were investigated as affected by stages of ripening (pink, ripening, maturity and Plasmolism) and variety (Super Bta and Petoerly-ch). According to the results at any treatment of variety and stage of ripeness, falling of tomatoes from maximum height of 59 cm does not occure any rupture in fruit, causes injury in tomatos as degradation as a kind of latent damage. However, the minimum energy required for rupture injury was about 1.58 J and.84 J in first and third stages of ripenening, respectively. According to the results of ANOVA, there are no differences between two varieties based on rupture injury, whereas, impact energy and especially stage of ripeness had significant effect on all types of mechanical damage in tomato fruit. Also, the results showed that the severity and rate of latent damage increase progressively, through to hours of storage of fruits in natural conditions. Ripenenning stage is the major factor affect severity of latent damage through hours after impact. Key words: Tomato Impact Latent damage Ripeness Mechanical injury INTRODUCTION loading, variety, texture, maturity, temperature, size, shape, etc., [4]. In this case, McColloch [5] reported on Mechanical damage is the major cause of postharvest hidden and cumulative bruising injury on tomato due to losses in fruits and vegetables [1] specially in dead load and impact corresponding to maner in which undeveloped countries and considerable research efforts tomato are bruised during commercial handling. Van are required in this relation. Mechanical damage occures linden, et al., [6] tried to present a method to evaluate in the postharvest handling system primarily in two ways: bruise damage in tomato and establish a method to impact forces and compressive forces. Excessive impact determine the bruise susceptibility of different tomato occure during harvesting, grading, handling and cultivars by a statistical model. Allende, et al. [7] transportation []. Among the perishable crops tomato characterized factors that determine puncture injury (Lycopersicon esculentum) is very susceptible to during handling of tomatos. Also, Desmet, et al. [8] mechanical injury. In a study of a tomato handling system accuired data on mechanical impacts using an Campbell et al. [3] found that up to 4% of the crop instrumented sphere to identify the critical points where sustained mechanical damage. puncture injury may occur in handling chain in Mechanical damage to tomato is manifested by water- postharvest operations of tomato. He also tried to predict soaked cellular breakdown of the cross-wall and cavity the puncture injury of a susceptible and not susceptible [4]. However, despite extensive development in cultivar under practical onditions. In addition, it was mechanical harvesting and handling of tomato, research mentioned that tomatoes at harvest were less on resistance of this product to mechanical damage has susceptible to puncture injury than after storage for been limited. The bruise susceptibility of fruits and several days [8]. Geyer et al. [9] reported the vegetables depend on many factors such as severity of incidence of cracks and bursts after harvest and Corresponding Author: Shahzad Jamaati-e-Somarin, Young Researchers Club, Islamic Azad University, Ardabil Branch, Ardabil, Iran, Tel: , jamaati_1361@yahoo.com. 97

2 Am-Euras. J. Agric. & Environ. Sci., 9 (3): 97-3, 1 Van Zeebroeck et al. [1] investigated to verify the (impact levels) cosidered in the experiments (Table 1) hypothesis that within a cultivar higher absorbed according to classification of severity of impact handling energy of tomato also indicates higher bruise damage systems. In this classification two broad categories: when impacted by the same impact energy. low energy system (less than.9 J) and High energy However, bruises are not always immediately visible system (about 1.5 J) are introduced []. but they become noticeable during subsequent handling An impact pendulum apparatus developed at the shelf life [6]. In this case a rilaible description is not university of Mohaghegh Ardabili, department of available. Another factor which affects tomato bruising is agricultural machinery [11], with 15 cm lentgh of the stage of ripening which considered in the researches pendulum wire, was used to apply controlled impact very seldom. Hense, it is useful to consider fruit energy to each fruit. The whole fruits of tomato were degradation after impact, which cause some type of sujected to impact after measuring the weight and 3 deterioration of fruit and is known as latent damage, in principal diameters of the samples. addition to rupture injury, which cause the water loss of fruit. Damage Susceptibility: To investigating damage Therefore, the objectives of this study is: (i) to susceptibility, it is usual to develop a relatonship between identify critical ripeness stages where rupture may the impact energy and size of damage in the form of area occure; (ii) to determine the effect of stages of ripeness or volume of damage. This teqchnique was utulized by on fruit degradations after impact; and (iii) to compare Mohsenin [4]. But in tomato fruit, it is very hard to two varieties of Super Beta and Petoerly-ch in relation to detect the bruised area because of little or absulutly no mechanical damage. skin or flesh colour change. Accordingly, in adition to considering direct rupture injury, immediately after each MATERIALS AND METHODS test the samples were evaluated for any change on the skin of tomatoes as a kind of fruit deterioration. To obtain Sample Preparation and Impact Test: Two varieties of an accurate evaluation the following bruise classes were tomato (Super Bta and Petoerly-ch) were examined in the defined which could show damage severity (Table ). impact tests and for each cultivar, 16 tomatos were hand To evaluate the latent damage it was necessary to picked directly from orchard in random and stored at 18 C consider the deterioration of fruits during hours after (as in real process in comercial procedure) for 16 days. impact. Therefore, at three stages (, and hours Four stages of tomato ripeness, means: pink, ripening, after the impact) the visual evaluations were done. During maturity and plasmolism, mached to 1, 6, 11 and 16 days this priod the storage condition was 18 C and 8% after harvest, respectively, were considered in the tests. relative humidity (natural environmental condition in For each treatment 1 replications were utilized. comercial handling in the region). All statistical analysis At each ripeness stage the moisture content of was performed using the Mstat-C statistical software, in samples were measured. Also, two levels of height of drop the form of a randomized factorial experimental design. Table 1: Different impact levels and their mean values used in the experiments Drop Height (mm) Impact energy (J) Level (1.4) Level (.4) Table : Class index for different types of deteriorartion after impact Type of deterioration no bruis little skin softness medium skin softness severe skin softness black area with little faded completely faded Class Index I II III IV V VI 98

3 RESULTS AND DISCUSSION Am-Euras. J. Agric. & Environ. Sci., 9 (3): 97-3, 1 Table 3 sumerized the physical conditions of the samples in the experiments. It could be seen that the moisture content increase until 11 days after harvest and then decreased in plasmolism stage. Indeed, it is a natural phenomena in which unsoluble liquids such as Pectine transform to simple compositions which caused the water to freedom and increasing water amounts in fruit flesh. Also, during 16 days after harvest in the environmental condition of 14 to 18 degree of centigrade (Plasmolism), tomato lose a fraction of its water. According to obtained results, at any treatment of Fig. 1: Rupture and its location on bottom of fruit variety and duration of time, falling of tomatoes from maximum height of 59 cm does not occure any rupture in statistical regression model, indicate that the percent of fruits. Whereas, in falling of fruits from 118 cm height the rupture (Z) depend only to stage of ripeness (X) minimum rate of ruptures occurred in 3% of the samples (Figure ): at first stage of ripness (Table 4). However, the minimum 3 z=a+bx +cx (1) energy required for rupture injury was about 1.58 and.84 J in first and third stages of ripening, respectively. Nearly Based on this result, it is prefered to use a D model in all samples, rupture occurred at the bottom of the fruit (Eq. ). Indeed, a simple linear model define the where the fruit joint to stalk (Fig.1). It seems that the relationship between percent of rupture (Z) and stage of impact caused to develop the fllaws which exist at the ripeness (x) exactly (r =.89). bottom of the fruit as like as the results of the compression tests on similar varieties [1]. Z= x () It was observed that the percentage of rupture was increased proportional to development of ripening stage According to the results of analysis of varience, (Table 4). Figure shows that the rate of rupture does not there are no differences between two varieties based on depend on rate of kinetic energy. Eqation (1) as a 3D mechanical injury, whereas, impact level and stages of Table 3: physical specifications of the samples in various treatments Var. Supper-Beta Petoerly-ch Stages of Ripeness MC (%) Weight (gr) MC (%) Weight (gr) Pink Ripening Maturity Plasmolism Table 4: Percentage of rupture injury in various treatments Var. Supper-Beta Petoerly-ch Days after harvest Time Stages Ruptured (%) Energy (mj) Ruptured (%) Energy (mj)1 Pink Ripening Maturity Plasmolism

4 Am-Euras. J. Agric. & Environ. Sci., 9 (3): 97-3, 1 1 Rupture Time Pink Stage 4 4 I II III Severity of IV Deterioration V I II III IV Severity of Deterioration V Energy Fig. : Percentage of rupture increase proportional to stage of ripeness (Time) (r =.9) Ripening Stage Fig. 3: Quantity and severity of damage during hours after impact in Petoerly-ch variety and at first stage of ripness (pink) Fig. 4: Quantity and severity of damage during hours after impact in Petoerly-ch variety and at second stage of ripness (ripening) ripeness had significant effect on all types of mechanical damage (ruprure and latent damage) on tomato fruits. The same results obtained for interaction of impact level and stage of ripeness. 1.7 Maturity Stage I II III IV Severity of V Deterioration Fig. 5: Quantity and severity of damage during hours after impact in Petoerly-ch variety and at third stage of ripness (maturity) The results showed that at a constant level of impact energy, which did not yield any form of skin rupture, the factor of rippening level significantly affected severity and quantity of damage. In other words, it is very important to know the level of ripening stage, that impacts occure after it. Indeed, when impact done on tomatoes in pink stage, it did not reach to sixth class of damage (VI), even after hours storage in natural condition. In this relation, figure shows that only % of samples reached to fifth class of damage (V ). However, when tomato received impacts after second, third and fourth stages of ripeness (means: ripening, maturity and plasmolism) quantity and quality of damage increase progressively. Altough, there is a considrable difference between ripening stage and two later stages. Indeed, if the fruit recieves impact after ripening stage only % of samples yield the most severe damage, means completely faded and 4% of samples yield to black area and with little faded. While, if the impact occure on tomatoes after third and fourth stages of ripeness, 1% of samples involve fifth and sixth levels of deterioration (Figures 3 to 6). Accordingly, we can distinguish a critical condition between second and third stage of ripeness (ripening and maturity) of tomato in which latent damage increase in quantity and severity (Fig. 7). These results were similar in both varieties (Super Bta and Petoerly-ch). It is important to notice that, in every two varieties and in a constant level of kinetic energy (59 mj), between 5 to 1% of damage occure in fruits, if the impact takes nd rd th place after, 3 or 4 stage of ripness and its severity increases with the increase of ripness stages. While the similar amount of kinetic energy did not make any form of damage in fruits at least at hours after impact. 3

5 Am-Euras. J. Agric. & Environ. Sci., 9 (3): 97-3, 1 Plasmolism Stage I 3 II III 1 IV Severity of V Deterioration Damage StagesOfRipeness Storage Fig. 6: Quantity and severity of damage during hours after impact in Petoerly-ch variety and at fourth Fig. 9: Percentage of increasing of rupture proportional to stage of ripness (plasmolism) stage of ripeness (Time) (r =.86) Damage (%) 1 8 Damage No Bruise Little Softnes Medium Softnes Sever Softnes Little Faded Complete Faded Plasmolism Maturity Ripening Pink Fig. 7: Quantity and severity of damage based on stage of ripeness in Petoerly-ch variety Stora.. As shown in Figures -5, the duration of storing fruits in local natural condition (18 C and 8% relative humidity) had a significant effect on quantity and severity of latent damage in tomato fruits. This result was similar in two varieties under this study. Consequently, it is reasonable to propose for any suitable change in environmental condition of tomatoes, sudenlly after impact. This result could be seen in figure 8. Equation (3) shows that the rate of damage (z) could be modelled as a linear surface and based on this model the time of storage (in natural condition) is the main independent parameter (y), while the stage of ripeness (x) has the minor effect (Figure 9). z=a+bx+cy+dy (3) REFERENCES 1. FAO., Prevention of postharvest food losses: fruits, vegetables and root crops. FAO Training Series No. 17/. Food and Agriculture Organization of the United Nations, Rome, Italy.. Shafiur Rahman, M., Handbook of Food Preservation. In: Food Science and Technology, Vol. 94., CRC Press. 3. Campbell, D.T., S.E. Prussia and R.L. Shewfelt, Evaluating postharvest injury to fresh market tomatoes. J. Food Distribution Res., 17: Mohsenin, H., Physical Properties of Plant and Pink Animal Materials. Gordon and Breach Science Ripening Maturity Publishers, New York, NY. Stages of Ripeness Plasmolism 5. McColloch, L.P., 196. Bruising injury of tomatos. Fig. 8: Effect of duration of time after impact on quantity U.S. Dept. Agric. Mkg. Res. Rpt. No. 513, of damage in different stage of ripeness Washington, D.C. 31

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