Pulp-wash extracts

In the extraction of citms juices it is desirable to have as gende an extraction pressure as possible. There should be minimal contact time between juice and pulp to reduce the amount of bitter substances expressed from the peel into the juice. The amount of suspended soHds in citms juice is controlled in a subsequent separation in a finisher. A screw action is used to force the juice through a perforated screen and separate the larger pulp particles from the juice. The oil level in the juice is adjusted by vaporizing under a vacuum (10). The separated pulp is washed and finished several times to produce a solution which is then either added back to the juice to increase juice yield, or concentrated to produce pulp wash soHds, also called water extract of orange soHds, which can be used as a cloudy beverage base. 

The pulp recovered during screening may be transferred to a pulp-wash operation to yield further soluble solids by counter-current extraction with water. The washed pulp may be held for further processing or included with the bulk of ejected peel material from the extractors. This is milled, treated with lime (calcium hydroxide or calcium oxide) to break down pectin and reduce water retention, pressed, dried to c.10-12% moisture content and finally converted to pellets. Being high in carbohydrates these are used as filler in livestock feed blends. 

Viscosity poses a similar problem in the production of pulp wash concentrate. Pulp wash consists of juice solids obtained by countercurrent washing of pulp after its separation from juice. On a °Brix basis, pulp wash liquids are higher in pectin than juice from which the pulp has been screened (19). Concentration of pulp wash above 40°Brix is at times hampered by excessive pectin levels (20). To control viscosity processors may be forced to reduce finisher pressure to minimize pectin extraction, thereby curtailing yield. A more effective solution is to treat pulp wash with pectinases to reduce pectin levels (21). If pectinases are incorporated into the wash water, this method has the advantage of increasing total solids yield by reducing juice retention in the pulp. 

The juice vesicles, or "sacs," remaining after juice extraction and pulp-washing may be included in the portion of peel residue dried as cattle feed. However, it is feasible to recover and utilize this material as either frozen (3) or drum-dried juice sacs (44). 

Royo Iranzo and Aranda (1 ) and Royo Iranzo et aK (2) found from one half to one third of the commercial European bottled orange juices tested were adulterated. Mears and Shenton [3) reported the most common form of adulteration in the early 1970 s was the use of fruit by-products such as extracts of peel and pulp (pulp-wash). It appears that the problem has continued into the 1980 s. Three orange juice surveys in the United States (162 samples obtained from retail outlets) conducted by the Florida Department of Citrus during 1979 and 1980 indicated gross adulteration by orange pulpwash (PW) and/or sugars and/or dilution (Petrus et al., unpublished data). 

Another possibility is to produce concentrate from the recovered juice solids as such, so-called pulp wash concentrate , or OWP (Orange Wash Pulp) or WESO (Water Extracted Solids) respectively. 

Adulteration of fruit juices and concentrates is a problem that has received wide publicity. Common methods of adulteration either alone or in combination include addition of water, corn syrup, cane and beet invert sugar, peel extract, pulp wash, cheaper... 

Adulteration of orange juice by the addition of an aqueous extract of the pulp, which remains after pressing of the juice (pulp wash), is detected by the marker N,N-dimethylproline. The levels of this amino acid are higher in pulp wash than in juice. 

In another extractor (Automatic Machinery and Electronics Inc. (AMC)) the individual fmits are cut in half as they pass a stationary knife. The halves are oriented in a vertical plane, picked up by synthetic mbber cups, and positioned across plastic serrated reamers revolving in a synchronized carrier in a vertical plane. As the fmit halves progress around the extractor turntable, the rotating reamers exert increasing pressure and express the juice. The oil and pulp contents in the juice increase with greater reaming pressure. The recoverable oil is removed in a separate step prior to juice extraction. Needle-sharp spikes prick the peel of the whole fmit, releasing oil that is washed away with water and recovered from the oil—water emulsion. 

Extra.ction St ige. The washing step after the chlorination stage removes the chlorine. In alkaline extraction, about 1.5—3.5% NaOH based on pulp is used. This typically amounts to about 55% of the CI2 demand used in the chlorination stage (% NaOH = 0.55 x % CI2 ). The target pH exiting the... 

A pilot plant ia India has been estabUshed to extract fiber, pulp, and juice from the leaves of sisal plants. The fiber is sold direcdy or used to manufacture rope, the cmshed pulp is used ia paper processiag, and the juice is an excellent source of hecogenin. During a three- to five-day fermentation of the juice, partial enzymatic hydrolysis causes hecogenin to precipitate as the hemisaponin ia the form of a fine sludge. This sediment is hydrolyzed with aqueous hydrochloric acid, neutralized, and filtered. This filter cake is washed with water and extracted with alcohol. The yield of hecogenin varies between 0.05 and 0.1% by the weight of the leaf (126). 

The manuf of NC is similar in that it involves the same nitrating acids as used for TNT, but used to treat cotton linters or wood pulp (raw cellulose) in a series of vats and reactors similar to the ones used for TNT. The crude NC is similarly subjected to a series of w and aq soln washes until it is finally delivered as a purified, fibrous mat — ordinarily wet with w or ale for safety. Again, there are major wastewater streams laden with spent reagents and extracted impurities... 

Black liquor is 13 to 17% strength, rinsed extract from washed and cooked woodchip pulp, produced in the Kraft pulping process. This... 

Wet beet pulp (campaign 1991) was obtained, after sugar extraction, from CSM Suiker bv (Breda, the Netherlands). After two consecutive HjO washings of the beet pulp (40°C, 30 min) pectic polysaccharides were obtained by an autoclave treatment (two times,... 

Sugar (sucrose) is obtained from either sugar beets or sugarcane. Sugar beets are traditionally diffused with water to extract the sugar from the pulp. The sugar is then crystallized, mechanically separated, and washed to produce white sugar. 

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