Washed orange pulp

Hamlin and Valencia washed orange pulp from several crop years were dried and analyzed. The range in values of total pectin, neutral detergent fiber and crude fiber were 26.0-45.6%, 15.8-31.0% and 9.9-20.6% respectively. In addition, detailed nutrient and dietary fiber analyses were obtained for selected samples. Functional properties such as flavor muting, chromatophore formation and oil holding properties were noted. Food processing modification yields a novel form of the hydrated pulp with extended functional properties. 

Interest in dietary fiber has refocused attention on a known but underutilized fiber source washed orange pulp. 

Its precursor, orange pulp, is that tissue produced upon expression of orange juice from the juice vesicles. With further extraction(s) of residual soluble sugars from the pulp, an osmotic re-equilibrium occurs to yield the washed orange pulp. This washed orange pulp is obtained as a hydrated complex of vesicular carbohydrates at 4-10% solids. 

As a byproduct of the juice concentrate industry, an estimated 500,000 to 1,000,000 tons of wet pulp are produced each crop year. Unlike suggested more exotic sources of dietary fiber, orange pulp is already an established, commonly consumed food component in the American diet. The functional and nutrient properties of washed orange pulp are intimately related to a series of factors. The foremost of these is the orange species but also significant are climatic and crop year variants, harvest maturity, expression and extraction processing variables, uncontrolled enzymatic and microbial activity as well as method of drying. Because of variations in the material, application and development as a fiber has been limited. 

Solvent extractions were performed by treatment of 100-150 grams of 93% moisture washed orange pulp in a Soxhlet apparatus charged with 600 ml of acetone or isopropanol. The extraction was continued 3-6 hours by which time no additional yellow pigment could be observed in the extracting solvent. 

The tissue mass was dried at ambient temperature until no detectable residual solvent was evident. Aqueous extractions of the 93% moisture washed orange pulp were performed with 0.4 M sodium citrate, 0.2 M EDTA, 0.1% H PO, 0.5% Na2C0, and 5% NaOH solutions in respective experiments In each case 200 ml of extracting solution was added to 100 grams of pulp and stirred for three hours of 25 C. After filtration the extracted tissue was washed three times with 200-250 ml of 50°C distilled water and filtered. Those samples for OHC or WHC were then freeze dried. Samples for microscopic examination were kept in the hydrated state. 

Washed orange pulp, obtained from FMC juice finishers is a relatively homogeneous fraction of the juice vesicle (4). 

Hamlin and Valencia washed orange pulps were obtained and analyzed and the results are presented in Table I. 

Figure 1. Washed orange pulp (juice vesicles). Key a, whole juice vesicle, I3X> b, enlarged view of vesicle surface showing pectin ridges, 140x, c, scanning electron microscopy (SEM) of untreated fuice vesicle, 200X and d, scanning electron microscopy (SEM) of drum-dried washed orange pulp, 220X-...

The property of dried citrus pulp to be "wet" by oils has been described by Kesterson and Braddock (8). Washed orange pulp solids normally contain 0.5-1.5% ether extractible lipids. Also present is cuticular wax which gives lipophilic character to the pulp solids (9). Both the water holding capacity (WHO) which encompasses sorption and hydration phenomena, and oil holding capacity (OHC) which can be described in terms of adsorption and capillary entrapment of... 

COMPONENT COMPOSITION OF WASHED ORANGE PULP ADJUSTED TO MOISTURE AND SUGAR-FREE BASIS (a)... 

COMPOSITIONAL AND NUTRIENT ANALYSIS OF DRUM DRIED VALENCIA WASHED ORANGE PULP AND AACC REFERENCE WHEAT BRAN (a.b)... 

FIBER ANALYSIS OF EEC/IARC REFERENCE SAMPLES. AND HAMLIN WASHED ORANGE PULP, % DRY MATTER... 

Utilization of washed orange pulp in food processing and product applications was explored. In one specific case, the hydrated pulp was combined with ungelatinized starch, edible acids, nutritive sweeteners and additional water. The mixture was heated and the system brought to 48-53% solids from the 30-40% solids starting level. This process leading to an ingredient is the basis of U.S. patent 4,232,049 (12). 

OIL AND WATER HOLDING CAPACITIES OF WASHED ORANGE PULP... 

Washed orange pulp was evaluated as an unconventional source of dietary fiber. The pulp is an excellent source of soluble and insoluble dietary fiber. Dried samples generally contain 25-45% pectins and 9-20% crude fiber. Several properties of the pulp are a function of its cellular components and must be considered in utilization as a food ingredient. Additional functional properties can be obtained by processing the hydrated pulp and have extended the potential use of this byproduct of the juice concentrate industry. 

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