All custard or cream filled pastries shall be kept refrigerated at all times between May 1st and October 31st, inclusive, of each calendar year, at a temperature not higher than fifty degrees Fahrenheit, except when actual sale is being made. The apparatus used in filling such pastries shall be made of metal or rubber and cleaned before each use, by means of boiling water or live steam or other suitable method. (Prior code § 6270.8)