.lri upproriniately qnunlitulice delerniirmtion
the colloidal material in some forly samples of American honeys, representing a zariety of floral types, is accomplished by ultraJiltraliori through standardized collodion films. The colloid content of honeys of various types ranges from alniost 1 per cent for some dark honeys [e. g., buckwheat) to less than 0.1 per cent for light honeys such as clocer and orange. Honey colloids consist largely of nitrogeneous substances (proteins), highly emulsified wax particles, pentosans, and inorganic constituents. Colloids lower the su.rface tension and increase the viseasily of honey, and are the primary cause of turbidity. Frothing and “caramelizalion” of honey upon heating are materially lessened by remuing colloids. Examination of several honeys discloses the presence in each case of amino acids or closely related compounds. The reaction of these compounds with dextrose and levulose to produce dark-colored subslances (Inelanoidiru) plays an importunt role in the darkening of honey when it is heated or when it is stored at ordinary temperature. roperticsoflioney. When the ultrafiltration and u.ashing were completed, tlie resulting aqueous colloid suspensioii was evaporated a t low teniperature and finally dried to coiistant weight in a vacuum oven a t 40' C . (vacuum of 29 to 30 inches, or 73.7 to 76.2 cm., of mercury). It was thus possible to obtain an approsimately quantitative measure of the colloid content of honey. P r e liminary tests with buckwheat honey showed that closely agreeing resu1t.s could be obtained when colloid determinations were made with a number of films prepared by the authors' standard procedure. The greatest difference in eight determinations was only 0.02 per ceiit when the total colloid content was approximately 1 per cent. The pcrcentage of tlie total colloid content of honey retained by collodion films is very difficult to deterniine in the case of a complex product such as honey. IIowcver, determinations rriade with a series of collodion films of progressively diminishing porosity sliowed no material increase in retention by films of lcss porosity than those uscd i n obtaining the data liere reported. Approximately complete retention ma? obtained with several laboratory-prepared colloidal suspensions of varying degrees of dispersion. It is believed that the data linve definite comparaldve value, particularly d l i respect to honeys of different floral types.
Cor,i.orn CONTENT AND Cor.oi< Is The colloid content and color iriteiisity (color muubcr measured by the U. S. standard lioncg color grader, 28) of thirty-seven sainplcs of honey were determined. Tlie rcsults are given in Table I. The colloid content of most of tlie samples was quite small, the averege for all samples being approximately 0.19 per cent. Buckxvlieat honey had the largest colloid content, almost 1 per ccnt. Buckwheat., and the darker honeys in general, contained larger quantities of colloids than light honeys such as clover and orange. Althougli the relative colloid content and the order of color intensity do not correspond esactly in every case, a general relation does exist between these t,wo VRIUCP.
COLOF.
NrMasn"
% Buekwheat Heartsease (Me.)
Spanish peedle pep,,: Yine Hawmian honeydm
Aater
5. DisAssEMnLEu PnESsUnr: ~LTRAFILT11ATIONUNIT
U ~ p e rsootion of filter, showing aiimine arrangement and prea8ure eonne~tions IC. Middle section of filter C. Bottom motion of filter D . Support for oollodion film (psrfoietsd mom1 plate covered with 100-meeh mmel screen) 6 t a into grooved bottom ~ e c l i o o . c. of film B . l
