The effect of using aloe vera gel and calcium chloride on the shelf life and quality properties of peach fruit

Dissertation for Master's Degree in Horticulture Science

Summary:

Using healthy compounds compatible with human health and nature is one of the important concerns of technology researchers after harvesting garden products. The aim of this research was to investigate the effect of oral coating of aloe vera gel and calcium chloride on the shelf life and quality characteristics of the saffron variety peach fruit. Aloe vera gel treatment in concentrations of zero, 20, 25 and 33% and calcium chloride treatment in three levels of zero, 0.5 and 1% and also different combinations of these treatments were applied. The experiment was conducted as a factorial based on a completely random design in 5 repetitions. The examined traits included the amount of vitamin C, soluble solids, pH of fruit juice, titratable acids, firmness of fruit tissue, total phenol, total antioxidant, and the activity of catalase and polyphenol oxidase enzymes. The results showed that the treatment of 1% calcium chloride and 33% aloe vera gel prevented the increase of pH during the storage period, and the treatment of 33% aloe vera gel caused the maintenance of titratable acids. The process of increasing soluble solids in the treatment of aloe vera gel was 33% and the combination of this treatment with calcium chloride was slower by 0.5 and 1%. Combined treatments of aloe vera gel and calcium chloride maintained vitamin C levels at a higher level than the control. Calcium chloride treatments led to an increase in hardness and 33% aloe vera gel treatment led to maintaining the hardness at the end of the storage period. The highest amount of total phenol was related to the combined treatment of aloe vera gel 25% and calcium chloride 1%, and calcium chloride treatments led to maintaining the total antioxidant capacity. The amount of catalase enzyme activity increased by 33% in aloe vera gel treatment with 1% calcium chloride, and the 33% aloe vera gel treatment prevented the increase in polyphenol oxidase enzyme activity.

Key words: aloe vera gel - calcium chloride - saffron variety peach - qualitative properties - storage life - edible coatings

Chapter One

Introduction

Today, in addition to population growth, due to scientific and economic advances, food consumption has increased. One of the ways to maintain health and reduce the risk of diseases is to consume sufficient amounts of healthy foods daily (Kader, 2002). Evidence shows that healthy food includes sufficient amounts of fruits and vegetables that contain various vitamins (vitamins C, A, B1, B3, B6, and E), dietary fibers, indoles, glucosinolates, thiocyanates, isothiocyanates, coumarins, flavonoids, phenols, etc. In addition, fruits and vegetables supply 16% of magnesium, 19% of iron and 9% of calories needed by the human body. The waste of agricultural products occurs in three stages before harvest, during harvest and after harvest, but it seems that the main part of the waste of perishable agricultural products is related to the stages of harvest and after harvest until reaching the hands of the consumer. In the meantime, the goal of specialists after harvesting is to identify factors affecting waste and use appropriate technologies to reduce them (Kader, 2002).

Fruits and vegetables are highly perishable products that require proper handling and storage conditions to minimize waste, and garden products are naturally ready for destruction due to their high water content. They are biologically active and the processes of respiration, evaporation and transpiration and biochemical activities lead to loss of product quality (Thumula, 2006). In developing countries, for perishable products such as fruits and vegetables, storage, packaging, and transportation technologies have not been developed yet, and therefore a large amount of them are lost during these processes (Thumula, 2006). During the transportation of these products, suitable tools with controlled temperature and relative humidity should be used. Proper packaging of fresh fruits and vegetables has a significant effect in reducing waste after their harvest (Kader, 2005).

1-1- Origin and history of peach planting

The origin of peach (Prunus persica L) is from China, where the history of its cultivation dates back to 3000 years ago.It is possible that peaches were taken to Iran through mountain trade routes and became known as Iranian fruit [1]: this name has led some people to think that the origin of peaches is from Iran (Crisosto et al, 1994). Three hundred and thirty years before Christ, peach arrived in Greece, and during the Middle Ages, the planting of this tree spread throughout Europe. Apparently, the Portuguese brought peaches to the east coast of South America. The Spanish took peaches to Florida and Mexico, the French to Louisiana, and the English settlers to Virginia and Massachusetts. In Spain, peaches with yellow and firm flesh were common, while in France and England, fruits with white flesh and soft texture were more desirable. Finally, these two sources of hereditary reserves were mixed together (Agawa et al., 2011).

1-2- Classification and botanical characteristics

Peach belongs to the genus Alu Sanan, subgenus Amygdalus and genus Gholserkhian, the height of the trunk of this tree is 4-6 meters and its crown is curved. Ornamental varieties of peaches are short. The trunk of the tree is straight and vertical, and the height of the trunk depends on the method of training and guiding it. Peach has a semi-dense crown and its main branches are lacquered brown. Thin or young branches are darker in color than the main branches. It has two types of vegetative and reproductive buds. Vegetative buds are small and pointed, but fertile buds are swollen and wide-tipped. Peach reproductive buds are simple buds and each bud produces one flower. Peach cultivars grown in Iran include G, H, Hill, Alberta, Spring Time, Spring Crest, Red Top, Sun Crest, Dixie Red, Haj Kazemi, Anjiri Peach, Urmia Red, and Sard Rood (Jalili et al., 2018). FAO [2] (2008), 18 million tons of peaches and nectarines are produced all over the world, and China is the largest producer of this product in the world with a production of eight million tons per year. The first ten peach producing countries in the world are presented in Table 1-1. The annual production of peaches in China has increased several times since 1980, so that today its production cannot be compared with other producing countries. In the United States, California is the largest producer of this product in that country and supplies 75-70% of all peaches in the United States (FAO, 2008).

Abstract:

Use of safe and environmentally friendly compounds is one of the most important challenges in postharvest research Current study was conducted to determine the effects of Aloe vera coating and CaCl2 on storage life and quality attributes of Zaferani peach fruits. Aloe vera gel at 0, 20, 25 and 33 percent and calcium chloride at 0, 0.5 and 1 percent and different combinations of these treatments were used in a completely randomized experiment with five replications. Vitamin C content, total soluble solids, pH, total acidity, fruit firmness, total phenolics, total antioxidant capacity, catalase and polyphenol oxidase enzymes activity were measured after 15 and 30 days of cold storage. The results showed that 1% CaCl2 and 33% Aloe vera gel decreased the rate of increase in pH and 33% Aloe vera gel retained fruit TA. Increasing of TSS in 33% Aloe vera gel treatment and in combinations of this treatment with 0.5 and 1% CaCl2 were slower. Combination treatments of Aloe vera gel and CaCl2 retained vitamin c content in higher level than control. At the end of storage calcium chloride treatments increased and 33% Aloe vera gel retained fruit firmness. Highest level of total phenolics was recorded in combination treatment of 25% Aloe vera gel and 1% CaCl2 and calcium chloride treatments retained total antioxidant. Catalase activity at combination treatment of 33% Aloe vera gel and 1% CaCl2 increased and 33% Aloe vera prevented increasing of polyphenol oxidase activity.