PRODUCTION AND PROPERTIES OF IN-CAN STERILIZED CONCENTRATED MILK WITH39-PERCENT-SOLIDS - PROCESS OPTIMIZATION

A number of strategies has been found to be effective for control of t he extent of age-gelation of sterilised milk concentrate containing le cithin. By reduction of the homogenisation pressure applied during man ufacture, not only was initial heat stability enhanced but the extent of age-thickening during storage at 20 and 45-degrees-C was also moder ated. There was no concomitant increase in fat separation as a result. Reduction of the fat content by standardisation of the fat: solids ra tio to 0.29 has a similar beneficial effect on both initial heat stabi lity and on thickening during storage. The effect of heat treatment be fore sterilisation was dependent on the stage during manufacture at wh ich the heating was applied. For example, as the severity of heat trea tment of unconcentrated milk increased, the ultimate properties of the sterilised product tended to improve. However, application of heat to concentrate before sterilisation had a deleterious effect. The positi on of addition of lecithin was also critical. Addition to concentrate before homogenisation yielded optimum effect. There was evidence of di fferences in efficacy between different types of lecithin.