The nutritional significance of tea is confined to certain vitamins and minerals. Tea is able to contribute riboflavin, folic acid, /3-carotene, ct-tocopherol and phylloquinone, and is also one of the more significant sources of fluoride in the UK diet. The pharmacological action of caffeine in tea is so modified, probably by its interaction with polyphenols, that the beneficial properties of the alkaloid may be enjoyed without harmful side effects. Beneficial effects attributed to tea polyphenols acting synergistically with ascorbic acid include the strengthening of capillary blood vessels and an anti-atherosclerosis action. The potential value of tea has been well recognised in Russia but has received scant attention in the West.

Tasting of pure compounds and various fractions isolated from black tea liquors suggests that, with the exception of caffeine, none of the characteristic monomeric nonvolatile substances contributes significantly to the taste of the beverage. The most

The natural peroxidase and catalase of tea leaf were shown to be active under the conditions employed for the fermentation of minced tea leaf in aqueous suspension. Fermentations carried out under nitrogen with ethyl hydrogen peroxide, which is not decomposed by catalase, yielded predominantly thearubigins, a high proportion of which were polymeric in nature. Fermentations using an excess of hydrogen peroxide gave similar results. Fermentations under conditions of controlled dissolved oxygen using both air and hydrogen peroxide resulted in a pigment distribution intermediate between those observed using air alone and using ethyl hydroperoxide under nitrogen. Adjustment of the amount of hydrogen peroxide used to around 120 pmol 8-1 leaf resulted in a pigment distribution closely similar to that of a good quality black tea. A mixture of theaflavins was stable in the presence of air and tea polyphenoloxidase but decomposed rapidly to yield polymeric materials under the action of hydrogen peroxide and peroxidase derived from tea or horseradish. Kinetic measurements suggest that tea flavanols are generally poorer substrates for peroxidase than for catechol oxidase. However, the level of peroxidase is high and, furthermore, in view of the respective pH optima of the two enzymes, its action would be favoured as the pH falls during fermentation. It is postulated that the nature and distribution of the pigments formed during the fermentation of tea is governed in part by the relative actions of catechol oxidase and peroxidase. These actions are, in turn, influenced by the availability of oxygen and the action of catalase.

The total synthesis of mycolipenic acid has been completed. (+)-2(L): 4(L)-Dimethyldocosanoic acid * (I), an oxidation product of mycolipenic acid which has been previously synthesised, was converted essentially by a route already described for an optically inactive specimen into (+)-2 : 4(L) : 6(L)-trimethyltetracos-2-enoic acid (IV; R = H). The synthetic acid, regarded as the trans-isomer, is found to be identical with mycolipenic acid isolated from tubercle bacilli.

Rapid thin‐film counter‐current dialysis of a typical infusion of black tea indicates that 10–12% of the soluble solids are non‐dialysable. the major components of this fraction are polysaccharides and a complex mixture which could not be separated into its protein and polyphenolic constituents. This latter complex accounts for 30–40% of the colour (E450) of the infusion. Solvent extraction of the infusion followed by dialysis of the various extracts reveals that the polyphenol‐protein complex may be approximately equated with ‘SII thearubigins’. Chromatography of infusions and various extracts thereof on alkylated Sephadex allows a partial separation of the coloured components largely owing to differences in molecular size. At least 7 distinct zones can be recognised.