S U M M A R YTreatment with 60 yo hydrofluoric acid (HF) removed most of the phosphorus and small amounts of mannan, glucan and protein from walls of two nonflocculent strains ( N C Y C~~~ and NCYCI004) and two flocculent strains (NCYCIOOS and NCYC I 063) of Saccharornyces cerevisiae. Organisms of all strains showed increased flocculating ability following H F treatment. Flocculation of untreated organisms of NCYCIOOS and N C Y C I O~~, and of HF-treated organisms of all four strains, declined appreciably when they were washed in deionized water, with or without EDTA, and the flocculation was measured in deionized water instead of in 0.05 M-sodium acetate containing Ca2 +. Treatment with I ,a-epoxypropane also caused a decrease in the flocculating ability of these organisms. Extracting the lipids from organisms of strains N C Y C~~~ and N C Y C I O O~ had no effect on their flocculating ability, but decreased the flocculating ability of organisms of strains NCYCIOO5 and N C Y C I O~~. pH-electrophoretic mobility curves of untreated and HF-treated organisms confirmed the loss of wall phosphate by H F treatment, and indicated that HF treatment had little effect on the content of protein carboxyl groups in the outer wall layers. Mannose at 0 . 2 2~ completely prevented floc formation by organisms of strain N C Y C I O~~ ; but, even at 0.33 M, it had very little effect on floc formation by HF-treated organisms of strains ~c u c 3 6 6 and ~c u c r o 6 3 . Organisms of all four strains bound fluorescein-conjugated concanavalin A to the same extent after treatment with HF as before, but this treatment led to a greatly diminished binding of fluorescein-conjugated antiserum raised against organisms of strain N C Y C~~~. The results indicate that phosphodiester linkages in yeast-wall mannan are not involved in bridge formation through Ca2 + during floc formation and that this arises principally through carboxyl groups.

The malting quality of Sri Lankan sorghum was studied using seventeen varieties. These varieties represented four colour categories (brown, yellow, pink and white) of sorghum found in Sri Lanka. The main criteria used for the assessment of malting quality in this study were the malting loss, diastatic power, liquefying power and the quantity of extract. Malting losses of these varieties were somewhat higher than those encountered in malting barley. However, they appeared to depend partly on the malting conditions. The diastatic powers and liquefying powers observed in this study were inferior to those observed with barley malt. However, with some varieties they appeared to be adequate for the purpose of mashing, as indicated by the high extract values obtained, which were comparable with those of some barley malts. Extract values of the four colour categories varied considerably and the best values were observed with the yellow and pink varieties and some varieties of white. Brown varieties in spite of their comparatively high diastatic powers and liquefying powers gave very little or no extract on mashing.

Seventeen strains of yeast, isolated from samples of fermented coconut palm wine (toddy) by direct plating, were characterised and identified using both biochemical and morphological characteristics. The yeasts belonged to five genera : Saccharomyces (10 strains), Pichia (two strains), Torulopsis (two strains), Canrlida (two strains) and Wirigea (one strain). The predominant species were Saccharomyces cerevisiae (four strains) and Saccharomyces exiguus (four strains).

Thirty six strains of yeasts isolated from some fruits and fruit products were identified using their biochemical and morphological characteristics. These yeasts belonged to six genera viz: Candida (Sixteen strains), Kloeckera (nine strains), Hanseniaspora (three strains), Pichia (four strains), Saccharomyces (three strains) and Tomlopsis (one strain). The most predominant species was Candida krusei (Ten strains).

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