Taste thresholds esters

Hop oil contains a series of thioesters (Table 13.7) the combined amount of which in steam-distilled hop oil usually exceeds 1000 ppm. The level of thioesters in the oil does not appear to be affected either by treatment of hops with elemental sulphur on the bine or by sulphur dioxide kilning [50]. Thioesters are formed in hops largely by the action of heat, so low levels will be introduced into beer by dry hopping. Few sulphur volatiles survive 60 min of wort boiling but after late addition of hops to the copper most of the sulphur compounds discussed above are present in the wort including the thioesters. During fermentation dimethyl trisulphide and some of the thioesters disappear but some sulphur volatiles survive into the finished beer S-methyl 2-methylbutanethiolate is the principal thioester to survive. This last ester and 5-methyl hexanethiolate, the thioester with the lowest taste threshold, are the major thioesters introduced into beer by dry hopping [50]. 

A commercially interesting low calorie fat has been produced from sucrose. Proctor Gamble has patented a mixture of penta- to octafatty acid ester derivatives of sucrose under the brand name Olestra. It was approved by the FDA in January 1996 for use as up to 100% replacement for the oil used in preparing savory snacks and biscuits. Olestra, a viscous, bland-tasting Hquid insoluble in water, has an appearance and color similar to refined edible vegetable oils. It is basically inert from a toxicity point of view as it is not metabolized or absorbed. It absorbs cholesterol (low density Hpoprotein) and removes certain fat-soluble vitamins (A, D, E, and K). Hence, Olestra has to be supplemented with these vitamins. No standard LD q tests have been performed on Olestra however, several chronic and subchronic studies were performed at levels of 15% in the diet, and no evidence of toxicity was found. No threshold limit value (TLV), expressed as a maximum exposure per m of air, has been estabhshed, but it is estimated to be similar to that of an inert hpid material at 5 mg/m. ... 

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