This study used a tomato variety of Martha / TW at breaker stage with the weight ..... Coatings for Food itpplicanons, edt by M.E. Embuscado and K.C. Huber.
Sesame and Lemon Grass Oils as Coating Materials to Reduce the Deterioration of Tomato Fruits during Storage I Made Supartha Utama*, Ni Luh Yulianti*, Oki Adhi Prastya* and Greg Luther** * Department of Agriculture Engineering, Faculty of Agriculture, Udayana University, BaliIndonesia ** The Asian Vegetable Research and Development Center (AVRDC) - the World Vegetable Center, Shanhua, Taiwan
Abstract Tomato fruits are produced and consumed in most countries in the world; and therefore, tomato is an important vegetable for human consumption. Due to the postharvest nature of the fruit, the involvement of postharvest handling technologies is important to reduce damage and losses during the postharvest period, especially in the region of which is lack of cold chain in its supply. Efforts to develop a simple and cost-effective technology to reduce the postharvest spoilage of tomato fruits, particularly for developing country where the cold chain are not well established, is very important. This study aims to determine the effect of the different combined concentrations of sesame oil and lemongrass oil as a coating material on the postharvest losses of tomato fruits stored at room temperature. The results showed that 0.5% sesame oil and 0.5% lemongrass oil in the oil-water emulsion is the best combination in reducing post-harvest losses of tomato fruits. Key words: Tomato, sesame oil, lemon grass oil, fruit coating, postharvest deterioration
Introduction Tomato is one of horticultural products demanded by consumers since it is a source of vitamin C and minerals, and is multipurpose as vegetables, table fruit, juices or drinks. Tomato is a commodity that is classified as susceptible to damage (perishable). Postharvest losses of tomato fruit is mostly due to improper handling and it could reach by up to 35.5% which was depend on the distribution chains (Yoga et al., 2011). The postharvest losses include physical, physiological, mechanical and microbiological damages. Therefore, necessary efforts to maintain fruit quality and extend the shelf life of fresh tomatoes are important. Coating of tomato fruits is a method of applying a thin layer film on the surface of the fruit to inhibit the release of gases, water vapor so that the fruit ripening process and shriveling can be slowed. The materials used as a coating material has to be able to form a barrier layer on the surface of the fruits, and does not harmful for human consumption and be able to extend the shelf life of the fruit. One of the types of coating materials that can be used on fruit and vegetables is oil-based coating materials. This material can also serves as a carrier of various functional compounds such as emulsifiers, antimicrobials and antioxidants (Pavlath and Orts, 2009) It was reported that emulsion of sesame oil on tomato fruit as a coating can increase the shelf life of tomatoes at room temperature (Utama et al., 2013). Lemongrass oil,
which is one of naturally-plant derived oils, is known to have strong antimicrobial properties (Banjole and Joda, 2004). This article reports the effect of coating of different concentrations of the mixture of sesame and lemongrass oils and the most appropriate concentration of the both combination to maintain the quality and extend the storage life of fresh tomatoes at room temperature.
Methods Materials and Equipments This study used a tomato variety of Martha / TW at breaker stage with the weight range of 100120 grams and the diameter of 4-6 cm. The tomatoes for experiment were directly harvested from the garden of a farmer in the village of Candikuning, Bedugul, Bali. Vegetable oils used as coating materials were sesame and lemon grass oils. Additional materials used to make oil emulsion were polystearate or tween 80, oleic acid and ethanol . The equipment used were a digital scale (Adventurer TM Pro Av 8101, New York, USA), blender, refractometer (Labo brand 10807), colorimeter (Accu Probe, New York, USA), and texture analyzer (TA - XT plus, England). Experimental Design The design used for the experiment was completely randomized design with two factors. The first factor was the concentration of sesame oil, which was varied, namely 0% (S0), 0.5% (S1), 1% (S2), and the second factor was the concentration of lemongrass oil, which was varied, namely 0% (L0 ), 0.5% (L1), 1% (L2), 1.5% (L3) in the oil-water emulsion. There were 12 different combined concentrations of sesame oil and lemongrass oil that were S0L0, S0L1, S0L2, S0L3, S1L0, S1L1, S1L2, S1L3, S2L0, S2L1, S2L2 and S2L3. The treatments were repeated three times with storage at room temperature (2730oC). Data were analyzed with analysis of variance and if there was a significant effect of treatments, the analysis was continued with Least Significant Difference (LSD) test for the average of treatments. Experimental Preparation The harvested tomatoes were sorted to get tomatoes with intended colour, weight and diameter and the defected fruits were discharged. Tomatoes were washed to remove residual dirt. Coating was of the fruits was performed by dipping the fruits in the emulsion. The coated fruits were then air-dried. The unit of experiments consisted of 15 fruits and was laid on the room temperature. During the storage, the fruits were observed every three days. Observed Parameters Weight loss The weight loss in percent was measured using the formula below. Where; W t0 is the weight at day-0 and Wtn is the weight at the day of measurement.
% of weight change = [(Wtn – Wt0)/Wt0] x 100
Hardness Fruit hardness measurement was performed using a texture analyzer that was connected to the computer and open application of "Texture Exponent 32". Cylinder probe of 6 mm in diameter, depth of 10 mm and speed of 5 sec per mm and depth of 10 mm, were used for measurement of the hardness of the fruits. The level of hardness was indicated in the unit of kg/cm2. Intensity of Decay or Spoilage The formula below was used to measure the intensity of spoilage of each experimental unit of the fruits. Before the calculation, the spoilage of individual fruits in the experimental unit were given ratings as shown on the Table below. The formula was the adaptation of the formula given by Townsend and Hueberger (Kremer and Untertenshofer, 1967) to estimate the rate of percentage of disease incidence. Where 0 means no infection and 6 means the maximum rating indicating more than 50% of individual fruit is infected by spoilage microorganisms. Table 1. Infection of individual fruit in the unit experiment and the rating of infection Infection on individual fruit (%) 0 1-10 11-20 21-30 31-40 41-50 >50%
Intensity of decay per unit experiment (%)
Rating 0 1 2 3 4 5 6
=
∑ (n x v) ----------------- x 100% N x V
where : n = the number of chili fruits in each ratings v = the ratings of spoilage N = the number of fruit per unit of experiment V = the maximum rating (6)
Result and Discussion Weight Loss The results revealed that there was a significant interaction between the concentrations of sesame oil and lemongrass that affected the variation of the data (P
