Effect of Storage Method on the Physicochemical and Sensory Qualities of Orange Juice
The Objective of the Study
The objective of the project study was to examine the effect of storage methods on the physicochemical and sensory qualities of orange juices.
Overview of Orange (Citrus sinensis)
The sub-genus Citrus (Swingle), family Rutaceae and subfamily Aurantioideae is of three types: Citrus, Fortunella (Kumquat) and Poncirus Trifoliata. There are three genera and eighteen defined species, but other natural mutations exist resulting to numerous hybrids which are widely spread throughout the world (Guo and Deng, 2001). Citrus is widely grown in Nigeria and many other tropical and subtropical regions (Piccinelli et al., 2008). In terms of volume in production, citrus ranks after banana as the world second fruit crop with more than 108 million tons (FAO Statistics, 2006). Sweet orange (Citrus sinensis L. Osbeck) commonly called orange is a member of this family and a major source of vitamins, especially vitamin C, sufficient amount of folacin, calcium, potassium, thiamine, niacin and magnesium (Angew, 2007). Economically, oranges are important fruit crops, with an estimated 60 million metric tonnes produced worldwide as at 2005 for a total value of 9 billion dollars. Of this total, half came from Brazil and the United States of America (Goudeau et al., 2008; Bernardi et al., 2010). The global citrus acreage according to FAO statistics in 2009 was nine million hectares with production put at 122.3 million tons, ranking sweet oranges first among all the fruit crops (Xu et al., 2013).
Oranges probably originated from south East Asia, and were cultivated in China by 2500 BC (Nicolosi et al., 2008), where it was referred to as ‘’Chinese’’ apple (Ehler, 2011). Today, it is grown almost all over the world as a source of food for humans because of its high nutritional values, source of vitamins and other uses. Propagation through seed is associated with problems like poor pollen production, self-incompatibility and muscular embryo. Therefore budding onto appropriate rootstocks is the common means of assuring the reproduction of cultures of known quality. Arsingrin (2011), posited the use of tissue culture to produce good quality plantlets, but are highly susceptible to root diseases, and this limits production (Katzer, 1999). This paper reviews the importance of oranges to human health, the impact of diseases on its production and control measures that should be adopted to realise its maximum benefits in the promotion of human health.
Sweet orange (Citrus sinensis L. Osbeck) (to distinguish it from closely related species like sour orange, C. aurantium C. reticulata and mandarin orange), is a small evergreen tree 7.5 m high and in some cases up to 15 m. It originated from southern China where it has been cultivated for many years, but is today grown commercially worldwide in tropical, semi-tropical and some warm temperate regions to become the most widely planted fruit tree in the world (Nicolosi et al., 2000; Ehler, 2011). Orange produces leathery and evergreen leaves of different shapes, ranging from elliptical to oblong to oval, 6.5-15 cm long and 2.5-9.5 cm wide, often bearing narrow wings on the petioles. It bears fragrant white flowers either singly or in whorls of 6, about 5 cm wide, with 5 petals and 20-25 yellow stamens. The small, white or purple scented hermaphroditic flowers produce nectar for pollination by insects. The fruit, which may be globose to oval is 6.5 to 9.5 cm wide, and ripens to orange or yellow. Anatomically, the fruit consists of two distinct regions (Fig. 1): the pericarp also called the peel, skin or rind, and the endocarp, or pulp and juice sacs. The skin consists of an epidermis of epicuticular wax with numerous small aromatic oil glands that gives it its particular smell.
The quantity of wax is dependent on the variety, climatic conditions and growth rate. A plethora of microflora consisting mainly of fungus and bacteria are present on the skin and more copious in damp climates. This justifies the need for appropriate washing of the fruit before eating or proceeding to extract juice and essential oils. The pericarp consists of the outer flavedo, or epicarp largely made of parenchymatous cells and cuticle. Embedded oil glands create terpenoid aromatic compounds such as valencene, limonene, and alpha/beta sinsenal (Goudeau et al., 2008; Sharon-Asa et al., 2003). Beneath the epidermis is the flavedo, with its characteric yellow, green or orange colour. The flavedo is very fine and fragile containing oliferous vesicles on the inside which can be collected by scraping on the flavedo layer. The flavedo is a generally colorless, spongy inner layer of mesophyll that changes character and thickness throughout fruit development, properties that determine ease of peeling. The albedo, or mesocarp lying beneath the flavedo consists of tubular-like cells joined together to constitute the tissue mass compressed into the intercellular area. The albedo is rich in flavonoids, which if transferred to the juice imparts a bitter taste (Sharon-Asa et al., 2003).
The flesh or pulp of the fruit is typically juicy and sweet, divided into 10 to 14 segments (although there are seedless varieties) and ranges in color from yellow to orange to red. The ripe fruit is classified as a hesperidium which is a type of berry with multiple seeds and is fleshy. Fleshy juice sacs accumulate sugars, organic acids and large amount of water, causing difficulties in the extraction of nucleic acids and proteins. The endocarp and the carpels in which the juice containing vesicles are found and which from a synthetic biology point of view should be considered as the liquid released by the cytoplasm and by the vacuoles in the vesicles’ internal cells. A spongy tissue similar to that of the albedo constitutes the greater part of the fruit.
MATERIALS AND METHODS
Fresh Sweet Orange (Citrus sinensis L) was purchased from ogbese market and was transported from to the Department of Food Science and Technology in Rufus Giwa Polytechnic, Owo, Ondo State. The processing took place in the processing laboratory of Food Science and Technology and the analysis were carried in the chemistry laboratory.
Fresh and wholesome sweet orange purchased were sorted, divided into four groups namely A to D. Group A was processed immediately to obtain juice which serve as control sample. Group B was stored on the shelf for 7 days before processing. Group C was stored in a jute bag for 7 days prior to processing. Group D was stored in refrigerator for the same days then processed to juice. All the juice extracted were kept separately. Physicochemical, sensory and total viable counts were determined on them.
RESULTS AND DISCUSSION
Table 4.1: Physicochemical Properties of Orange Juice Samples
CONCLUSION AND RECOMMENDATIONS
The difference in the quality attributes of the different storage methods of orange juice may be attributed to the different storage conditions. Consumption of orange juice is desirable as they would serve as good sources of vitamins and body electrolytes. The results from this study show that the orange juice samples stored in refrigerator for 7 days would be the best storage methods since it preserves both the nutrient and qualities of the fresh juice (control sample COJS). In conclusion, orange processed immediately is consider best orange juice due to its untemper nutrient and sensory attributes however storage of the fruit using refrigerator before processing helps to preserve the nutrients and organoleptic properties of the juice.
Based on the finding of this study, it is therefore recommended that more research should be carried out on the antioxidant properties of orange juice stored using the same methods employed in this present study. Also for the sake of preservation it will be recommended to store orange fruit and other food products using refrigerator since it preserve the nutritional properties, organoleptic attributes and also prolong the growth of microbes.
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