Physico‐chemical characteristics of orange juice cloud

Abstract

Orange juice is a suspension of heterogeneous particles in a clear serum. The size of the particles varies between 0·05 μm and a few hundred μm. The particles with a size below 2 μm constitute the stable ‘cloud’. This fraction consists of needle‐like crystals of hesperidin, chromoplastids, amorphous (rag) particles and oil globules attached to some of these particles. The adsorption of oil globules on the rag particles enhances their stability in suspension, by decreasing their density. The hesperidin crystals are formed partly by crystallisation immediately after juice extraction. All the cloud particles exhibit a negative charge, which decreases with decreasing pH. However, it seems that hydration rather than electrical charge is responsible for the stabilisation of the cloud. Heat treatment of the juice causes an increase in the number of fine particles at the expense of coarser ones. In this process some extraction of pectin into the serum also takes place but this has little significance on the cloudiness and cloud stability of the juice.

Prevention of Hesperidin Crystal Formation in Canned Mandarin Orange Syrup and Clarified Orange Juice by Hesperidin Glycosides.

“…Clarified orange juice might become cloudy during storage because of the formation of hesperidin crystals and then interaction with pectin (Ben-Shalom et al, 1985;Mizurahi & Berk, 1970). As HGS prevented the decrease in soluble hesperidin, the mechanism of the prevention of the cloud in clarified orange juice was also investigated using the model orange juice.…”

The effects of orange juice clarification on the physiology of Escherichia coli; growth-based and flow cytometric analysis

“…Depending on the filtration regime, three cloud populations of descending size could be observed. First, large particles of greater than 3 μm diameter most likely lightly-coloured large rag fragments, visible on 8 μm and 11 μm filters and giving rise to little colour change (Mizrahi and Berk, 1970). Second, small to medium size particles of between 0.7 μm and 3 μm, most likely the carotenoid-containing chromoplastids and small rag fragments; these bright orange particles were visible on the 1.6 μm and 1.2 μm filters ( Supplementary Fig.…”

Stabilization of guava nectar with hydrocolloids and pectinases

“…The Ministry of Agriculture and Supply, which is the regulatory agency of the processing industries of juices and fruit nectars and identity standards [5] defines guava nectar as a non-fermented beverage produced by dissolution of guava pulp (Psidium guajava L.) and sugars in drinking water, intended for direct consumption, with or without addition of acids. The attributes color and turbidity are decisive for the acceptance of juices and nectars, which should not present sedimentation or phase separation, even with preservation of the nutritional value and taste [6] . Phase separation is associated with chemical interactions, density between the disperse phase and dispersant, particle size and viscosity of the disperse phase.…”

“…The attributes color and turbidity are decisive for the acceptance of juices and nectars, which should not present sedimentation or phase separation, even with preservation of the nutritional value and taste [6] . Phase separation is associated with chemical interactions, density between the disperse phase and dispersant, particle size and viscosity of the disperse phase.…”