The effect of aloe vera edible coating with carrageenan and glycerol on red chili (Capsicum annum L.) quality during storage

Red chili (Capsicum annum L.) is one of horticultural commodities that rapidly damage due to has high water content, which is around 80-90%. High respiration rate can cause deterioration quickly and shorten shelf life at room temperature stored. In order to prolong shelf life of red chili pepper, aloe vera alone, aloe vera mixed with carrageenan and glycerol can be applied as edible coating. The aims of this study were to evaluate the effect of aloe vera coating, aloe vera mixed with carrageenan and glycerol on red chili pepper. Four treatments with three times repetitions were used and analyzed their effect on weight, total soluble solid, hardness and color changes on red chili pepper. The treatments were aloe vera coating alone, aloe vera mixed with 2% of carrageenan mingled with the different concentration of glycerol, 0.5%, 1% and 1.5%, respectively. Red chilli pepper without any coating were considered as control. All the treated and control red chilli pepper were stored for 15 days at law (10°C) and room temperature (30°C). The data obtained were calculated statistically using analysis of variance (ANOVA). The results showed that edible coating with carrageenan and glycerol stored at low and room temperature had a significant effect reduced in weight loss and coating weight loss of red chili pepper. However, soluble solids concentration, color, were not significantly affected by aloe vera coating with carrageenan and glycerol. The highest quality of red chilli pepper is detected with aloe vera coating mixed with carrageenan and glycerol with 2% and 0.5% concentrations, respectively.


Introduction
Large red chilies (Capsicum annum L.) have a high economic value and are widely used in both the food industry and home cooking.Large red chillies provide appetising taste and colour, are rich in vitamins, can be used as medicine and food ingredients.Large red chilies are one of the commodities that experience a high level of damage due to high water content which is around 80-90%.This affects the quality and shelf life of chilies.Chillies can only last 3-5 days in room temperature of 27-30℃, so chillies are prone to physical damage such as drying, withering and also watery swelling followed by the decay process.This is because chillies lose carbon during the respiration process and lose water as a result of the evaporation process [1].Therefore, in order to maintain the quality of chilies in the hands of consumers, proper post-harvest handling is needed in order to extend the shelf life while maintaining quality.
One of the potential ways is to apply aloe vera as an edible coating on large red chilies.Aloe vera gel has a potential as a useful coating to prolong the quality and freshness of fruits.This gel, which does 1230 (2023) 012170 IOP Publishing doi:10.1088/1755-1315/1230/1/012170 2 not affect their flavour or appearance, is natural and safe.The gel consists mostly of polysaccharides that act to block oxygen and moisture which can accelerate the decay process.Aloe vera gel is hygroscopic, so it can cover the pores of the fruit by forming a barrier on the fruit skin that can prevent water loss, so that it inhibits the respiration rate of the fruit with the environment.Metabolic processes in fruit can cause changes in weight loss, total acid, sugar content, and fruit colour during storage.In addition to the respiration rate, edible coating can also inhibit the transpiration rate (water loss).According to [1], aloe vera edible coating has the ability to maintain cell wall moisture in the fruit.
However, the problem is that aloe vera gel is easily diluted, so fillers from other natural ingredients must be added to maintain the consistency of the gel.One of the fillers added is carrageenan.Carrageenan used in the manufacture of edible coatings serves to control water content, increase viscosity and form a gel, and strengthen the edible coating layer.Carrageenan has low plasticity properties so that in the manufacture of carrageenan-based edible coatings, the addition of plastilisers is required in order to produce edibles that are more flexible and smoother.The potential plastiliser added is glycerol.According to the results of research by [2], carrageenan and glycerol-based aloe vera coatings can maintain the quality of strawberry fruit during storage.So far, it is not known what is the best concentration of carrageenan and glycerol added to the edible coating of aloe vera to coat large red chilli fruit.

Methods
The materials used were large red chilies, aloe vera, carrageenan, glycerol and alcohol while the tools used were knife, blender, basin, sieve, spoon, dropper, mortar, digital scale, refractometer, penetrometer, colorimeter, digital thermometer and refrigator.The study was conducted with five treatments and three replications for 15 days.Prior to store at cold (10 o C) and room temperature (30 o C), samples were dipped shortly with aloe vera coating, carrageenan and glycerol.Five types of treatments i.e: a. P0 = No treatment as control, b.P1 = Treatment with aloe vera coating, c.P2 = Aloe vera coating treatment with the addition of 2% carrageenan and 0.5% glycerol, d.P3 = Aloe vera coating treatment with the addition of 2% carrageenan and 1% glycerol, e. P4 = Aloe vera coating treatment with the addition of 2% carrageenan and 1.5% glycerol.Concentration of aloe vera, carrageenan and glycerol that used in each formula as follow:

Weight loss
Observations showed that large red chilies stored at room temperature experienced higher weight loss than large red chilies stored at cold temperatures.The lowest weight loss of the treatment after day 15 was the edible coating aloe vera with the addition of 2% carrageenan and 0.5% glycerol at cold temperature which is 12.06% while the highest weight loss is the control at room temperature which is 64.65%.The low value of weight loss of large red chillies with aloe vera edible coating treatment with the addition of 2% carrageenan and 0.5% glycerol was due to the characteristic of edible which has permeability to water vapour.P0 or control without edible coating experienced the highest weight loss of 64.65% compared to treatments P1, P2, P3 and P4 with edible coating.The sigificantly weight loss in untreated the control was detected on day 6 until day 9, from 18.31% to 43.37%, thus showed the percentage of weight loss from day 6 to day 9 was 7.64%; 8.63% and 11.78% respectively.This phenomenon indicated that chili untreated no barrier thereby the moisture water evaporate rapidly compare to chili treated thereby the fruit was found dried and decayed.These was confirmed by [3]found that different concentration of aloe vera coating was applied on eggplant at two different temperature (10 o C and 30 o C).The results showed that weight loss was significantly lower at 10 o C than that stored at 30 o C.During the stored period, hardness of eggplant decreased gradually at room temperature compare to cold temperature.Meanwhile, the lowest weight loss is P2 or aloe vera edible coating treatment with the addition of 2% carrageenan and 0.5% glycerol with a weight loss of 56.60%.Weight loss in fruit given edible coating is relatively low because edible coating is able to prevent water loss from the fruit.Edible coating is a good barrier against water and oxygen.This is in accordance with the opinion of [4], which states that the thin layer serves to inhibit the release of gas, water vapour on the surface of the fruit to prevent it from contact with oxygen, in order to slow down the decay of red chili weight loss during cold storage (10℃) for 15 days.Based on Table 1, the highest weight loss in cold storage is the same as room storage, namely P0 or control with a value of 21.54%.This shows that both in cold storage and room storage, the edible coating on red chillies has a significant effect in suppressing the weight loss of large red chilies during storage.The best treatment of aloe vera edible coating namely P2 or aloe vera edible coating with the addition of 2% carrageenan and 0.5% glycerol with a value of 12.06%.This is because the addition of 2% carrageenan and 0.5% glycerol can increase the selective permeable properties of the solution so that O2 entering the large red chilies is reduced and respiration is suppressed, therefore transpiration is inhibited which causing the decrease of CO2, energy and water coming out of the red chillies.The same findings by [3].Different concentration of aloe vera coating was applied on eggplant at two different temperatures (10 o C and 30 o C).The results showed that weight loss was significantly lower at 10 o C than that stored at 30 o C.During the stored period, hardness of eggplant decreased gradually at room temperature compare to cold temperature.Based on the results of the analysis of variance (ANOVA) test, a significant difference was found in the interaction between the addition of carrageenan with glycerol and storage temperature in the application of edible coating of aloe vera.The results of Duncan's further test (α = 0.05) in Table 1 show that chilies coated with edible coating with the addition of 2% carrageenan and 0.5% glycerol at cold temperature storage have a lower weight loss than control or untreated chilies.The lowest weight loss of the coating in the treatment after day 15 was the weight loss of the coating in the treatment of edible coating of aloe vera with the addition of 2% carrageenan and 0.5% glycerol at cold temperature which was 69.6% while the highest weight loss was the control at room temperature which was 93.6%.

Soluble solids concentration
Soluble solids concentration are a measure of the amount of sugar in the fruit.Fruits vary in sweetness determined by the soluble solids in the fruit.The breakdown of starch into simple sugar during storage is the cause of the increment in total soluble solids.The results of the mean value for the soluble solids concentration of large red chili fruit are indicated in units of Brix and measured using a refractometer.Aloe vera edible coating treatment with the addition of carrageenan and glycerol is proven to suppress the rate of total soluble solids in large red chillies.The value of soluble solids concentration of large red chillies in untreated or without edible coating aloe vera increases faster than the treatment treated.The best edible coating treatment is P2 or aloe vera edible coating with the addition of 2% carrageenan and 0.5% glycerol due to aloe vera coating mixed with 0.5% glycerol with addition of carrageenan inhibited moisture water loss and protects the surface of large red chillies during the stored period.It was confirm also by [5] that edible coatings of carrageenan and glycerol are able to protect the surface of the fruit therefore the respiration process that triggers the formation of sugar is inhibited.These finding has been confirmed by [6] at previous study that aloe vera coating was effefctive to enhance shelf life and were able to reduce weight loss of papaya fruits stored at cold and room temperature during 15 days.Aloe Vera coated was not only able to extend self life but also potential to preserve firmness and soluble solids concentration Cold temperature is proven to maintain the total soluble solids value of large red chili fruit due the cold temperatures can inhibit the rate of ripening in large red chilli fruits.It was confirmed as well by [6] that application of aloe vera coating delays ripening and extend the shelf life of papaya fruit.Soluble solids concentration at room temperature reached 22.7 о Brix, whereas at cold temperature was 12.2 °Brix.These was because the higher the temperature, the solubility of sugar in the big red chili fruit would be increased.

Hardness
The appearance of wrinkles on the red chilli skin is presumed to be due to the transpiration process which causes high water loss.The highest hardness decreased in large red chilies stored at room temperature due to spoilage occurred in P0 while the first increased in hardness due to drying occurred in P1.The slower increase in hardness was found in P2 and P3 on day 9, while P4 showed an increase on day 10.This proves that aloe vera edible coating on large red chillies with the addition of carrageenan and glycerol was able to maintain hardness compared to the control and aloe vera edible coating without the addition of carrageenan and glycerol.This is in accordance with the opinion of [5], stating that carrageenan and glycerol have one negative charge on each disaccharide with a tendency to form a strong gel.
The strength of this gel will increase the ability of carrageenan and glycerol to form edible coatings, therefore the level of fruit hardness can be maintained.The addition of 2% carrageenan and 0.5% glycerol showed that the decrease in hardness was lower than the other treatments.This was because the addition of carrageenan with higher concentrations and glycerol increasingly caused the absorption of O2 for the respiration process to be slightly inhibited so that the respiration rate was low.It was confirmed by [7] stated that edible coating served as a barrier to the carrier of the coating additive and increased the delay of the decay period as well as could inhibit bacterial growth and acts as a protector of the fruit skin thereby that the edible coating was able to protect the fruit skin from damage.Fruit softening has been directly related to the reduction of moisture content in the material.In addition, hardness could be caused by the inhibition of respiration or metabolic processes thus the breakdown of carbohydrates water-soluble compounds was reduced and the hardness of the fruit can be maintained.Large red chilies stored at cold temperatures were able to maintain the stability of the decrease in hardness than room temperature because cold temperatures could reduce the process of transpiration and respiration in large red chili fruits thereby as to slow down the drying and decayed of large red chilies.These was confirmed also by Nurdjanna [8], which stated that room temperature storage could not bind pectin oxidation therefore that more water comes out resulting in the texture of the fruit becoming soft and wrinkled.

Colour
Changes in the chili colour during storage can be caused by the breakdown of carotenoid pigments resulting in a darker colour.The decreased in L* value was greater at room temperature than at cold temperature because cold temperature could inhibit the occurrence of browning reactions.These was confirmed also by Fawzia [8], that low temperature was one of the factors that inhibit colour changes and browning reactions in apples during stored period.The a* value will increase along with the ripening process of the large red chili fruit, the longer the shelf life, the higher the a* value of the large red chili fruit.Figure 2 showed that aloe vera coating treatment on big red chili has a significant effect on changes in a* value.The average a* value in the control without aloe vera edible coating was higher than the other treatments.The increasing of a* value caused by an increasing the respiration rate and caused browning.These was phenomenon due to the freshness of chili is preserved since it could inhibit the respiration rate and reduced ethylene production.It was reported by [7] that the aloe vera coating retained the colour than untreated.They confirmed green chilli treated with aloe vera coating resulted its colour was almost two folds higher compare to control.The b* value was found significantly decrease in untreated (P0) at room temperature due to P0 resulted in faster maturation.All treatments showed a* value was decreased significantly during stored period.However, b* value of the P0 and the P4 or edible coating treatment of aloe vera added 2% carrageenan and 1.5% glycerol showed significantly increasing than the other treatments.This was because large red chilies untreated was no barrier that slowed down the browning reaction.These findings confirm as well by [9] that aloe vera coating could inhibit browing on green chili and maintain the quality.Also [1] said that coating was a method of providing a thin layer on the surface of the fruit to inhibit the escape of gas, water vapour and contact with oxygen, hence the ripening process and the browning reaction of the fruit can be slowed down.The P4 significantly decreased the b* value because the addition of glycerol to P4 was not resulting in an ineffective edible coating on large red chilies.Nawab [4] stated that the more the glycerol concentration added, the flexibility of carrageenan increased, however, the elasticity of edible coating or edible film decreased.
The colour change at cold temperature was lower compare to room temperature.This proved that low temperatures were effective to maintain the colour change in large red chilies.Of all the treatments, the greatest level of colour change was observed in P0 on days 5 and 6.This was because the control large red chilies on day 5 and day 6 stored a change in brightness from bright red to dark red.In contrast to the edible coating treatment, in which chilies coated with edible coatings were exelent to maintain colour than without edible coatings.This was confirmed as well by [7], which states that edible coatings were able to preserve product appearance and improve taste, texture and colour.

Conclusion
Edible coating with carrageenan and glycerol stored at low and room temperature had a significant effect reduced in weight loss and coating weight loss of red chili pepper but soluble solids concentration, color, were not significantly affected by aloe vera coating with carrageenan and glycerol.The highest quality of red chilli pepper is detected with aloe vera coating mixed with carrageenan and glycerol with 2% and 0.5% concentrations, respectively.

Figure 3 .
Figure 3. b* value during storage at room and cold temperature.

Table 1 .
Concentration of carrageenan, glycerol and aloe vera.

Table 2 .
DMRT (Duncan's Multiple Range Test) results of tomatoes weight lost during storage.

Table 3 .
DMRT (Duncan's Multiple Range Test) results of tomatoes hardness during storage.

Table 4 .
DMRT (Duncan's Multiple Range Test) results of Lightness (L*) value of tomatoes during storage.