Coating Guava Postharvest With the Use of Starch of Tamarind Seed and Pomegranate Seed Oil

The effect of coatings with different concentrations of tamarind seed starch associated with pomegranate seed oil in ‘Paluma’ guava was investigated in the present work. The fruits were harvested from an orchard in the morning, packed in containers previously lined with paper, and transported to a laboratory, where they were selected, washed, sanitized, and separated at random for the application of each treatment. The experiment design used was completely randomized, in the 6 × 6 factorial scheme, six coatings and six evaluation periods, with 3 replicates made up of 2 fruits. The treatments were: T1 (control or reference sample), without coating; T2 (0.24 mL of pomegranate seed oil/mL of coating); T3 (2% tamarind starch); T4 (1% tamarind starch); T5 (2% of tamarind starch); T6 (3% tamarind starch), T4, T5 and T6 were associated with 0.24 mL/mL of the pomegranate seed oil. The treatments were applied under immersion of the fruits in the solutions and then stored in a refrigerated chamber at 10±2 °C and 80±5% RH, and the evaluations were performed at intervals of 3 days to 12 days of storage. Due to the maintenance of the quality of the fruits, and without sufficient material, it was decided to extend storage time until the 21 days. Thus, the analyses were performed at 0, 3, 6, 9, 12 and 21 days with evaluations at 0, 3, 6, 9, 12, and 21 days. The T6 treatment (3% tamarind starch + 0.24 mL/mL pomegranate seed oil) was more efficient regarding luminosity (L*) of the fruits and delaying color development , expressed by the values of C*, also showing the higher retention in the loss of firmness, lower mass loss and lower soluble solids content, suggesting that this treatment possibly inhibited the degradation of polysaccharides, delaying the ripening process of the fruits.


Introduction
The guava (Psidium guajava L.) is a seasonal fruit found in the tropical and subtropical areas of the world.It is an excellent source of dietary fiber, pectin, vitamin A, phosphorus presenting the second largest vitamin content C of all of the fruits belonging to the family Myrtaceae.Also, it is rich in calcium, iron, thiamine, niacin, riboflavin, and carotene (Mangaraj et al., 2014).
The climacteric nature limits shelf life of post-harvest to 3 or 4 days to 25±2 °C, ripening quickly and entering in senescence (Murmu & Mishra, 2017).To minimize this, studies have been accomplished using edible coatings in order to improve the shelf life of these fruits.One of the materials that can be worked in the formulation of those coatings is tamarind seed starch.For being that one polysaccharide it possesses in its composition amylose and amylopectin, which serve as a barrier to gases, antifungal action, being able to preserve mechanical and sensorial properties.It can also present antioxidant actions, due to the fact that the fruit of tamarind rich in phenolic compounds, preventing the action of free radicals (Tremocolde, 2011).
The benefits of coatings based on starch and other substances associated of the incorporation of essential oils were demonstrated by different authors: Perdones et al. (2012), Sánchez-González et al. (2011), Teodosio et al. (2018), Santos et al. (2017).They studied the postharvest conservation of guava 'Paluma' through tamarind starch based coatings, and they verified that the concentration of 3% of the coating was more efficient regarding the brightness (L*) of the fruits and on delaying the development of the color, expressed for the values of C*, h*, indicating the potential of this product in the retention of the ripening and, consequently, resulting in longer preservation of the covered fruits.
The development of new studies with the objective of proving the effectiveness of this product as coating is of fundamental importance.In this context, the objective of this work was to study the effect of different concentrations of tamarind starch and pomegranate seed oil in formulations of coatings in the preservation and attributes of quality of the guava.

Material and Methods
The experiment was developed in the Federal University of Campina Grande (UFCG), Center of Sciences and Agro-Food Technology (CCTA), in the laboratory of Post-Harvest of Fruits and Vegetables, in the period of November to December 2017.The fruits were obtained from guava orchard, located in the state of Pernambuco, Northeast area of Brazil.The crop was accomplished manually between 6 and 8 hours of the morning, the picked fruits were in the state of maturation II, soon afterwards they were conditioned in a single layer, in containers previously coated with paper pricked to minimize the impact and the attrition among them and they were transported to the laboratory.
In the laboratory, careful selection was made for color size and uniformity, and absence of defects or mechanical imperfections.Afterwards, the fruits were washed with 1% neutral detergent solution and, after rinsing, sanitized with sodium hypochlorite solution containing 100 ppm of free chlorine for fifteen minutes.They were then randomly sorted in batches for the application of the treatments, which were composed of different suspensions based on tamarind starch and pomegranate seed oil.For the preparation of the suspensions and application of the coatings for the preparation of the suspensions and application of the coatings, the tamarind starch had semi-analytical balance weight and was diluted in 800 ml of water, the solutions were heated to 70 °C under constant stirring.The suspensions were cooled at 40 °C and then the pomegranate seed oil was added in the respective formulations.The starch and pomegranate oil used were obtained from Fazenda Águas de Tamanduá, located in the municipality of Santa Terezinha, Paraíba, Brazil.
The experiment was installed in completely randomized design, in the outline of factorial 6 × 6, six coatings and six evaluation periods along the time, with 3 constituted repetitions of 2 fruits.The treatments were the following ones: T1 (control or reference sample), without coating; T2 (oil of the seed of the pomegranate = 0.24 mL/mL); T3 (2% of starch of the tamarind seed); T4 (1% of starch of the seed of tamarind+ 0.24 mL/mL of the oil of the seed of the pomegranate); T5 (2% of tamarind starch + 0.24 mL/mL of the oil of the seed of the pomegranate); T6 (3% of starch of tamarind +0.24 mL/mL of the oil of the seed of the pomegranate).The coatings were applied immersing the fruits during one minute in the suspension, draining the excess, being disposed the same ones in drained containers.The fruits were then stored in a climatic chamber 10±2 °C and 80±5% RH, and the evaluations were performed at intervals of 3 days to 12 days storage.Due to the maintenance of the quality of the fruits, and without sufficient material, the storage was extended until 21 days.Then, the analyses were performed at 0, 3, 6, 9, 12, and 21 days.The following variables were analyzed: Colorimetry of the Peel: was accomplished being made use of the system L*, a* and b*, done by reflectometry, being used a reflectometer marks Konica Minolta, model Chroma to put CR-400.The readings were accomplished randomly in the equatorial area of the fruit.The measured color parameters regarding to plate-pattern were: brightness (L*), varying from black (0) to white (100); a*, varying from green (-60) to the red (+60) and b*, varying from blue (-60) to yellow (+60).The values of a* and b* are converted into Hue angle (H°), which represents color intensity, and their chromes (C*), that represents color purity according to the equations of Pinheiro 2009(Pinheiro, 2009).
Loss of Fresh Mass: It was measured in semi analytical scale with±0.01g accuracy, being used the connection between the mass of the fruit on the day of the crop and in the date of each evaluation.The results were noted in percentages; Firmness of the Pulp: measured after the removal of the peel of the fruit with a sheet of 10 mm.A digital penetrometer was used coupled to the ferrule measuring 8 mm in diameter.Two evaluations were made for each fruit, in opposite sides in the equatorial area.The results were expressed in N (AOAC, 2006); Hydrogen Ionic Potential (pH): certain for direct reading in the pulp homogenized through digital pH meter of bench with glass electrode (Marks Digimed DM-2 2), (IAL, 2008); Titratable Acidity (AT): accomplished through titration of 1g of homogenized pulp diluted in 50 mL of distilled water.Three drops of 1% phenolphthalein were added to the sample, titration was done under constant agitation, with solution of NaOH 0.1 N results were expressed as % of citric acid (IAL, 2008); Soluble Solids (SS): were measured through direct reading in digital refractometer Digital mark Refractometer (AOAC, 2006); Relationship between soluble solids and titratable acidity (SS/AT): made by the quotient among the two variables; Vitamin C: Obtained through titration with a solution of Tillmans, based on the reduction of the color sodic salt of 2.6 dicorofenol indofenol (DFI) for an acid solution of vitamin C. Initially, 1 g of the sample was weighed in an analytical scale, and transferred to an Erlenmeyer, completing the volume for 50 mL with 0.5% oxalic acid, resulting in an even rosy coloration permanent clearing.The results were expressed in mg/100 g % of ascorbic acid (AOAC, 2006); Statistical Analysis: The data were submitted to variance analysis and regression through the Sisvar Program (Ferreira, 2011).

Results and Discussion
In the variance analysis it was observed that there was significant interaction (p < 0.01) among the coatings and the time of storage for the variables vitamin C, loss of fresh mass, Luminosity L* and angle hue, demonstrating that the appraised factors influence in the quality post-harvest of guava fruits 'Paluma' (Tables 1 and 2).All the variables had significant difference separately for the time of storage.There was an effect of the treatments for the soluble solids (SS), Relationship SS/AT and pulp firmness.Note.ns: not significant;** significant at 1%;* significant at 5%.Note.ns: not significant;** significant at 1%;* significant at 5%.
Regarding the shine of the peel (L*), there was a significant increase, with interaction between the coverings and the time of storage.In the T1coverings (control or reference sample) and T2, there was an increase in the values

Table 1 .
Summary of variance analysis for the color parameters (brightness, chromaticity, and angle hue), loss of fresh mass and firmness of guavas 'Paluma' with and without the application of edible coverings during the storage at 10 °C, UFCG, Pombal-PB, Figure 1.B Figure 2

Figure
Figure 5. F

Figure
Figure 7. T

Table 2 .
Summary of the variance analysis for pH, titratable acidity (AT), soluble solids (SS), Relationship (SS/AT) and vitamin C guava 'Paluma' with and without the application of edible coverings during the storage to 10 °C, UFCG, Pombal-PB, 2017 ).