Citrus wash solids

In a study of yield and recovery of various citrus byproducts, it was reported that juice finisher pulp recovery was about 4.4 kg/100 kg of oranges and 2.7 kg/100 kg of grapefruit. Commercial recovery of soluble solids (ss) as pulp-wash should yield approximately 0.6 kg ss (oranges) and 0.2 kg ss (grapefruit) from 100 kg fruit (38). 

The pulp wash liquid from citrus fruit contains a higher amount of pectin than the single strength juice from the juice extractors. In most cases it must be treated enzymatically to achieve a sufficiently high concentration in the evaporator. In order to aid the concentration it is also commonly practised to centrifuge the liquid prior to evaporation to remove some or most of the insoluble solids from the liquid. 

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... 

Widmer (1991) reported good selectivity using a CN column under reversed phase conditions for analysis of limonin in citrus juices. Juice was passed through C-18 Sep-Pak solid phase extraction cartridge, the cartridge was washed with 30% (v/v) aqueous methanol, and was eluted with 70% methanol. The 70% methanol extract was used for HPLC analysis. Unlike acetonitrile extract, the 70% methanol extract was found to be stable for 30 days if kept at — 4°C. The extract was separated on a Supelco 5-p,m CN column, 4.6 X 250 mm, at 30 °C. A Brownlee 4.6 X 30 mm CN guard column was recommended. A mobile phase of acetonitrile and water (38 62) with a flow rate of 1.5 ml/min was used after washing the column with 10 ml acetonitrile. Retention time for limonin is about 6 min. UV detection at 210 nm or 214 nm was used. 

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