Protective maceration

Enzymatic maceration, which is a softening of plant tissue by the use of enzymes, has some potential quality advantages over mechanical-thermal disintegration as maceration is obtained with less damage to the cell walls. The major part of the plant cells remains intact by enzymatic maceration [25], as the enzymes attack only the space between the cells, and with only rare injury to the cell membrane [26]. The intact cells protect nutritional components within the cells which minimise flavour changes and deterioration on storage [27,28]. 

Since emulsion and synthetic fluids are potent defatting agents, the skin reaction to them may include maceration, dryness and chapping , reddening, and vesiculation. Bacterial growths in the fluid do not appear to be directly injurious to workers, but rancid fluids and products of bacterial action can lead to skin disorders. As in the case of insoluble oils, both treatment and prevention are based on the control of exposure. Corticosteroid creams may be used as an adjunct in the treatment. The value of barrier creams and other protective gels is not universally accepted but they do offer modest usefulness in certain situations and have been shown to reduce ul-trastructural and cytoarchitectural changes in human epidermis after applications of acetone and kerosene. 

In line with the principle, like dissolves like, one might think that the most suitable solvent for the extraction of water-soluble compounds is water. More often than not, however, simple maceration of fresh biological material with water or aqueous buffers fails to extract water-soluble compounds because they are mostly stored in protected states. The mechanism of such protection is varied binding to the membranes, compartmentalization, protection by lipophilic... 

The leaves and needles of plants possess a protective coating skin of cutin often referred to as the cuticle and which is highly resistant to decomposition processes. These cuticles thus emerge as another maceral of the exinite group that is termed cutinite. While not very abundant, this maceral is commonly found in most coals and is derived from the waxy outer coating of leaves, roots, and stems. 

Of 527 workers in a poultry slaughterhouse, 343 (65.1%) had skin diseases. This included 283 of 386 (73%) who worked in direct contact with the poultry, compared with 2 of 39 (5.1%) office workers or supervisors in the same industry. The most common skin problems were maceration and interdigital erosion, paronychion, pompholyx, and eczema and onychomycosis (Hayashi et al. 1989). The dermatoses were caused mainly by the wet work, and a marked reduction in number of dermatoses was seen after implementation of a program to protect the hands. 

Brown discoloration of nails may be caused by hair dyes and occurs in those hairdressers who neglect to use protective gloves. Transverse ridging, onycholysis and infiltrated nail folds occur in fingertip dermatitis. Nails may become soft and macerated by exposure to water, detergents and perm wave solutions. Sharp cut-hair parts may become implanted under the nails. 

Today, most red wines are fermented in tanks that can be closed when the carbon dioxide release rate falls below a certain level. The complete protection from air permits maceration times to be prolonged, almost as long as desired. The tank can be hermetically sealed by a water-filled tank vent (Figure 12.5) or simply closed by placing a cover on the tank hatch. In the latter case, the CO2 which covers the upper part of the tank disappears over time and the protection is not permanent. The tank should therefore be completely filled with wine or a slight pumping-over operation should be carried out twice a day to immerse the aerobic germs. 

Skin maceration in a membrane tank (Elite-Pera) is a process situated between maceration in a pneumatic press and tank maceration. At the end of maceration, the juice is collected first by natural draining and then by inflating the tank membrane, incrementally increasing pressure (0.1-0.25-0.4 bar). Ninety per cent of the juice can be collected by this method. The drained skins are transferred by gravity into the press with the help of a screw conveyer. The juices obtained by this method do not contain many suspended solids (200-300 NTU) and are particularly well protected from oxidation. 

This compartmentatlon would be lost during maceration of the tissue, as was demonstrated in corn seedlings by the five-fold increase in o-ketol concentration within ten minutes after mincing the tissue (33). It could be that Isomerases function to convert excess toxic fatty acid hydroperoxides to Innocuous ketol products as a protective mechanism. 

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