Removal of Astringency

D) Soaking the fruit in lime water for several days is an old method for creating the desired anaerobic conditions for removal of astringency in persimmon (Gazit and Levy 1963). 

Astringency is a common phenomenon in many unripe fruits, but generally it disappears when the fruit ripens on the tree. There are some exceptions to this, including many varieties of persimmon and date and some of banana, that remain astringent even when horticulturally mature. Astringency is a result of high contents of soluble tannins in the pulp. Removal of astringency is necessary for the fruit to be edible. 

Duff SJB, Murray WD (1990) Non aqueous reaction systems for the oxidation of higher molecular weight alcohols by alcohol oxidase from Pichia pastoris. In Charalambous G (ed) Flavours and off-flavours 89. Developments in food science, vol 24. Elsevier, Amsterdam, pp 701-713 Esguerra EB, Kawada K, Kitagawa H (1992) Removal of astringency in Amas Banana (Musa AA group) with postharvest ethanol treatment. Acta Hortic 321 811-820 Eskin NAM (1979) Terpenoides and flavonoides. In Plant pigments, flavours and textures. Academic Press, New York, pp 65-93... 

Sugiura A, Harada H, Tomana T (1975) Studies on the removability of astringency in Japanese persimmon fruits I. On tree removal of astringency by ethanol treatment (Part I). J Jpn Soc Hortic Sci 44 265-272... 

Fig. 3. Changes in results seen in tannin prints of freshly cut surfaces of Hiratanenashi persimmon at five stages of post-harvest treatment with ethanol vapour for removal of astringency. Top Before treatment bottom at the end of treatment + + + strongly astringent — not astringent (by sensory evaluation)...

During natural or artificial removal of astringency, soluble tannin can change, probably by polymerization or conjugation, into an insoluble form, which is not... 

Swain T, Hillis WE (1959) The phenolic constituents of Prunus domestica. I. The quantitative analysis of phenolic constituents. J Sci Food Agric 10 63-68 Taira S, Shimomura M, Oba S, Watanabe S (1990) Changes in soluble and total tannin content during fruit development and their relation to removal of astringency in Japanese persimmon Diospyros kaki Thunb.). Abstr XXIII Int Horticultural Congr, 27 Aug-1 Sept 1990, Firenze, vol 2, no 3279... 

Even higher proline contents have been reported in salivary PRPs these can contain 40-45 mol% proline and also have a substantial amount of glutamine. This protein binds ingested polyphenols, which precipitates the PRPs and removes the lubrication these normally provide. The result is the sensation of astringency (Green, 1993 Haslam and Lilley, 1988). 

Uses Removal of granulation tissue warts prophylaxis in bums Action Caustic antiseptic astringent Dose Adults Peds. Apply to moist surface 2-3 x wk for several wk or until effect Caution [C, ] Contra Do not use on broken skin Disp Topical impregnated applicator sticks, soln ophth topical ointment SE May stain tissue black, usually resolves local irritation, methemoglobinemia EMS None OD Unlikely... 

Since there are a number of astringent substances that may cause stagnation, Qian Cao Gen is used as corrective assistant. It can stop bleeding yet promote blood circulation. At the same time, it can also remove congealed blood. 

As a consequence of this effect there is an astringent taste, dryness in the tissues, cessation of glandular secretion and small wounds. Redness, swelling and increased secretion in inflamed tissue are diminished. As a result of the removal of the coherent coagulant membrane in the mouth and throat, the enclosed pathogenic microbes are also removed and the formation of new epithelium is stimulated. 

CA can prevent C2H4 induced formation of bitter isocoumarins in carrots (94) and can aid in removal of tanins and resulting astringency from persimmons (95.961. 

Amygdalin is present in bitter almonds, the seeds of Primus dulcis var. amara (DC.) Buchheim, and ripe apricot kernels, Prunus armeniaca L. (Rosaceae). The press cake, which remains after removal of the fatty oils, is macerated with water and left to stand for several hours, after which the essential oil is separated by steam distillation. The crude oil contains 2-4% hydrogen cyanide, which is removed by washing with alkaline solutions of iron(II) salts. Subsequent redistillation yields an oil free from hydrogen cyanide. It is a colorless to slightly yellow liquid with an intense, almond-like, cherry aroma and a slightly astringent, mild taste. 

Actions and Uses.—Externally —Stimulant, astringent, styptic, rubefacient, and vesicant. As a caustic for the removal of warts and similar growths. For the removal of scurf in ringworm, mallenders and sallenders, scab, and mange. ... 

Velioglu, Y.S., Ekici, L., and Poyrazoglu, E.S., Phenohc composihon of European cranberrybush (Viburnum opulus L.) berries and astringency removal of its commercial juice. Int. J. Food Sci. Technol., 41, 1011-1015,2006. 

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