Juice is the cell sap present in the cell vacuoles and expressed by squeezing from sound fruits. Orange juice is consumed in a natural cloudy state. The clarification would impair the appearance and flavor of the juice. Different types of orange juices are available in the market. The chilled single-strength orange juice has limited shelf life and requires installation of
expensive refrigerated tanks. The conventional pasteurized single-strength orange juice in cans is widely used, but the FCOJ is a commodity traded worldwide. Concentrated juices are distributed in large containers as a base for the manufac- ture of a variety of soft drinks. The same is reconstituted to single-strength juice for direct consumption. Comminuted or- ange products are prepared for use in beverages. Dehydrated juices in powder form are also available in the market.
Fresh Juice
Freshly squeezed, unpasteurized orange juice is desired be- cause of its fresh aroma and flavor, but the shelf life is less than 20 days at 1◦C, as it is highly susceptible to microbial spoilage. The manufacturing operations from fruit washing to packaging must be exceptionally clean to minimize product spoilage. Pectin esterase activity in unpasteurized juice re- sults in loss of cloudiness (Wicker et al. 2003). Due to this rea- son, product has to be maintained near freezing point through- out its distribution; however, cloud separation, flavor changes due to reactions with oxygen, and color instability still occur at a slower rate. Several days after packaging, diacetyl flavor, fused oils, and other microbiologically generated off-flavors make the product inferior to good quality pasteurized juice.
There is a risk of food-borne illness from consumption of unpasteurized packaged fruit juice. This includes salmonel- losis from consumption of contaminated fresh orange juice.
FDA has proposed juice regulations to mandate the use of hazard analysis and critical control point (HACCP) by most juice-producing companies and procedures for implementing HACCP have been published (Schmidt et al. 1997).
The method of juice extraction as well as the time–
temperature combination used for pasteurization had signif- icant effect on the quality of Nagpur orange during storage (Pareek et al. 2011). The juice extracted with a screw-type juice extractor and processed at 65◦C for 15 minutes gave better quality in terms of TSS, acidity, ascorbic acid, sug- ars, and nonenzymatic browning during 6 months of storage at room temperature. The contents of naringin and limonin in extracted juice were minimum with the screw juice ex- tractor and the processing at 65◦C for 15 minutes. The shelf life of fresh orange juice filled in nanocomposite low-density polyethylene (LDPE) films containing Ag and ZnO nanopar- ticles and stored at 4◦C has been studied by Emamifar et al.
(2010). They observed the least degradation in ascorbic acid (80.50 mg/100 g), lesser development of brown pigments (OD=0.23), and lower loss of color (⌬E =6.0) in fresh orange juice packaged in pouches containing 0.25% nano- ZnO during storage at 4◦C for 28 days. Compared with pure packaging materials, antimicrobial nanocomposite packages with Ag and ZnO as an alternative nonthermal technique can extend the shelf life of fresh orange juice up to 28 days.
The blood oranges are the major cultivated varieties ofC.
sinensis(L.) in Italy. Although fresh blood orange juice has high antioxidant activity because of a rich profile of pheno-
lics, its preservation is usually done by thermal treatments that affect its nutritional and sensory quality. Fabroni et al.
(2010) have proposed a milder continuous high-pressure car- bon dioxide (HPCD) process suitable for use on a commer- cial scale. The HPCD stabilized blood orange juice retains its physicochemical, antioxidative, and sensory quality for a shelf life of 20 days. Qiao et al. (2010) have compared the volatile compounds and chemical and physical properties of orange juice obtained from different parts of the Jinchen fruit (peeled juice, pulp juice, and whole fruit juice). The whole fruit juice was found to have the highest amounts of volatile compounds.
The distribution of volatile compounds in pulp, serum, and cloud of freshly squeezed orange juice has no relationship between the retention of aroma compounds in pulp or cloud and their lipid content or composition (Brat et al. 2003). Juice monoterpene and sesquiterpene hydrocarbons are primarily present in the pulp (74.0% and 87.2%, respectively) and cloud (7.3% and 14.9%, respectively). Esters and monoterpene al- cohols are mainly found in the serum (90.4% and 84.1%, respectively). Long chain aliphatic aldehydes tend to con- centrate in the pulp. The relative proportions of individual volatile compounds are similar in the pulp and cloud. Half of the alcohol insoluble residues in pulp and cloud are made of noncell wall proteins and the rest are made of cell wall materials. Pulp and cloud total and neutral lipids have sim- ilar fatty acid distribution, although cloud is much richer in total lipids than the pulp. The composition of orange juice in terms of total solids, sugars, acidity, and pectin is given by Money and Christian (1950) (Table 29.2). Table 29.3 shows the vitamin (USDA 1957) and mineral contents (McCance and Widdowson 2002).
Due to the presence of various bioactive compounds, such as flavonoids, flavones, and furocoumarins, there is a grow- ing interest in sour orange (Citrus aurantiumL.) products, mainly the liqueurs and marmalades (Barreca et al. 2011).
A simple and accurate method has been reported to si- multaneously separate and determine bioactive compounds by high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spec- trometry (HPLC–DAD–ESI/MS) in citrus fruits (He et al.
2011). The volatile flavor constituents from different types of orange juice have been characterized. Using solid phase microextraction–GC-MS, Niu et al. (2008) have identified 73 components, including 9 esters, 14 alcohols, 4 ketones, 8 aldehydes, 34 terpenic hydrocarbons, 3 alkanes, and BHT in 4 samples of fresh-sequeezed juice and 5 samples of “not- from-concentrate orange juice” and 2 samples of juice “re- constituted from concentrate.” In another study of three sam- ples from “not-from-concentrate orange juice, Zhang et al.
(2008) have identified 45, 52, and 51 aroma compounds in orange juices from Spain, Australia, and China, respectively.
The major aroma compounds were hydrocarbons, esters, al- cohols, ketones, and aldehydes. The aroma compound with the highest content was D-limonene (82%) in Spanish orange
Table 29.2. Total Solids, Total Sugars, Acidity, and Pectin Contents of Oranges Total Solids Total Sugars Acidity No. Pectin
Fruit (%) (%) (cc 0.1 N/100 g) (% as Calcium Pectate)
Orange(bitter)
Edible portion 13.59 5.49 3.30 0.86
Peel and pith 27.27 5.86 0.46 0.89
Juice 10.72 5.74 3.77
Orange(sweet)
Edible portion 12.98 7.88 0.79 0.59
Peel and pith 25.52 6.81 0.27
Juice 11.09 8.47 1.17 0.13
Source: Money and Christian (1950).
juice, 55.03% in Australian orange juice, and 60.96% in Chi- nese orange juice. The phenolic compounds isolated from pomace of grape cultivars have shown effective antifungal properties in orange juice againstZygosaccharomyces rouxii andZ. bailii(Sagdic et al. 2011).
Orange juice is the most popular fruit beverage enjoyed for its flavor and nutritional quality all over the world. How- ever, orange juice if contaminated with an acidophilic spore- forming bacterium,Alicyclobacillus acidoterrestris, coming from the soil, can results in off-flavors (Bianchi et al. 2010).
These researchers developed a rapid and reliable analytical method based on the volatile profile by dynamic headspace extraction followed by GC-MS analysis to early detect the spoilage of orange juice byA.acidoterrestris.
Pasteurized Juice
The consumer preference is increasing toward single-strength chilled juice. The necessity for food safety and quality re- quires pasteurization of juice before packaging and distri- bution. Many important nutrients in citrus juices including sugar, acid, vitamins, minerals, some flavonoids, and other components are quite heat stable under the conditions of pas-
teurization. Pasteurization process is designed to inactivate the thermally stable isoenzyme of pectin esterase. The tem- perature necessary for enzyme inactivation is higher than that required for killing the microbes. At a lower pH, the enzyme inactivation is achieved in a shorter time, thus producing a better quality juice. Juice treatment with carbon dioxide at above supercritical conditions has the advantage of enzyme inactivation without heat, thus preserving the natural flavor.
The juice maintains color and cloud stability throughout its shelf life (Lotong et al. 2003).
Aseptic Single-Strength Juice
Now, the technology is available on a large scale to extract, process, and store single-strength juice in bulk aseptic re- frigerated tanks, minimizing microbial spoilage and product quality deterioration. This technology enables provision of blended juices to consumers on a year-round basis, when the fruit is not in season. Depending on the processing capacity of the plant, number of tanks of capacity 950–3800 m3each, are installed in refrigerated rooms or insulated with refriger- ation. With proper nitrogen blanketing and mixing, the juice quality may be maintained for a year or more (Wilke 2002).
Table 29.3. Vitamin and Mineral Contents of Orange Juice
Vitaminsa Content Mineralsb Content (mg/100 g)
Vitamin A (-carotene) (IU/100 mL) 190–400 Na 1.7
Vitamin C (mg/100 g) 50 K 179.0
Thiamin (g/100 mL) 60–145 Ca 11.5
Niacin (g/100 mL) 200–300 Mg 11.5
Riboflavin (g/100 mL) 11–90 Fe 0.30
Pantothenic acid (g/100 mL) 130–210 Cu 0.05
Biotin (g/100 mL) 0.1–2.0 P 21.7
Folic acid (g/100 mL) 1.2–2.3 S 4.6
Inositol (mg/100 mL) 98–210 Cl 1.2
Tocopherols (mg/100 mL) 88–121
aUSDA (1957).
bMcCance and Widdowson (2002).
Single-Strength Juice from Concentrate A significant amount of orange juice is packaged from re- constituted concentrate as chilled juice. Because of the eco- nomics of storing large bulk quantities of concentrated citrus juice and the consumer preference for a ready-to-serve prod- uct, the volume of this product is large now. Pasteurized juice is packaged in cartons or glass containers and is microbio- logically stable. The flavor of juice from reconstituted con- centrate is not comparable with single-strength juice because of the two thermal treatments and the loss of volatiles during the concentration process. Addition of aromas and essences can improve the quality of the finished product (Ranganna et al. 1983).
Frozen Concentrated Juices
Concentrated orange juice with soluble solids content of 65◦Brix is now largely produced in the world. The pri- mary water removal technology is high-temperature short- time (HTST) evaporation, although freeze concentration and membrane processes are also used. The concentration pro- cess is accompanied by aroma recovery. The concentrate is blended with a small amount (less than 0.01%, v/v) of cold-pressed oil to mask the off-flavors that develop during storage. The small quantity of fresh juice can also be added back to concentrate to make up the losses of flavor during concentration process. The concentrate is chilled to –9◦C by passing through heat exchanger and pumped to large stain- less steel tanks maintained at desirable temperature in cold rooms. This concentrate is blanketed with nitrogen and care- fully monitored for quality characteristics, so that the juice with different characteristics may be accurately blended to produce a uniform-quality finished product. Under these con- ditions, the concentrate can be stored for over a year with little loss in quality (Ranganna et al. 1983).