Oils and Fats. 



12 



[January, 1909. 



conditions of shipping it are such as to 

 allow of sufficient absorption of water to 

 acilitate mould growth. 



To summarise this part of the paper :— 

 Six different moulds, any one of Avhich is 

 capable of hydrolysing and destroying 

 fat, have been isolated from the many 

 organisms growing on rancid copra. 

 This fat-destruction is part of the life 

 process of the mould, and is independent 

 of bacterial action. 



Copra acted on by moulds was found 

 to have suffered an almost total loss of 

 sugar. The bacteria found on copra 

 have very little effect on the quality or 

 quantity of oil produced. Their effect 

 is practically to produce a more or less 

 sour odour and bring about disintegra- 

 tion of the meat. 



It is good commercial practice to 

 prepare only the best, white, and per- 

 fectly-dried copra. 



The fourth and last note deals with 

 the production of free acid in commercial 

 coconut oil on long standing. Thirty- 

 five samples of oil of various conditions 

 were examined, and the table of results 

 provided show the percentage of free 

 tatty acids (as oleic) at the start, and 

 after two months, four months, six 

 months, one year and three years. 



The conclusion to be drawn may be 

 stated as follows : — The deterioration of 

 a freshly prepared commercial coconut 

 oil is produced by at least three entirely 

 independent processes, and may be 

 divided into two distinct periods of time. 



The first, rapid splitting up of the fat, 

 beginning immediately after its expres- 

 sion from copra and continuingf or several 

 months up to a year or more according 



to ,the nutritive matter present, is 

 occasioned by moulds which are either 

 pressed out with the oil together with 

 sufficient sugars and albuminoids for 

 their growth, or, in the case of hot 

 pressed oils, enter the freshly prepared 

 oil from the air. This action continues 

 as long as sufficient nutritive material 

 for mould growth remains in the oil. It 

 may be completely checked by filtration, 

 preferably after heating to 100° C. more 

 thoroughly to coagulate albuminoids and 

 to destroy any enzymes already secreted 

 by the moulds. 



Toward the end of this first period, 

 oxidation by the air sets in and may 

 continue indefinitely. The rate of this 

 process depends upon the amount of 

 surface exposed to the air, compared 

 with the total volume of oil, and may in 

 extreme cases cause an exceedingly rapid 

 deterioration. It may be entirely pre- 

 vented by storing the oil in completely 

 filled receptacles impervious to air. 



Along with the two above-mentioned 

 processes, a slight hydrolysis, due to heat, 

 moisture and free acids already present, 

 is constantly taking place. It may be 

 reduced considerably by filtration, which 

 removes most of the water, together 

 with the organic impurities, 



There is reason to believe that some 

 hydrolysis is brought about by enzymes 

 produced by the moulds, as unheated oils 

 which have been filtered and rendered 

 antiseptic increase in acidity somewhat 

 more rapidly than do heated ones under 

 the same conditions. However, this dis- 

 tinction is not so apparent after the 

 first year. 



Light has apparently no effect on the 

 oxidation by air of coconut oil. 



