MECHANISED MILK

Evening Post, Volume CIX, Issue 125, 29 May 1930, Page 17

MECHANISED MILK

MACHINE DEFECTS NO BACTERIA IN THE,FLUID OE THE WEONG IttND In these days nearly everything is mechanised. Mechanisation has iv some cases produced a better and a cheaper aiticlc. But in some cases it- baa, only produced a cheaper article. t ' That is tho complaint against mechanised music, and it is a complaint now against mechanised milk. Though'strongly entrenched behind labour-saving costs, the milking machine is no£ without critics. Mr. P. O. Veale, dairying researcli chemist of Hawera, blames the machine for some of tho defects in modern New Zeafand cheese In his report—which would have attracted nioi'o notice if New Zealand 'a political meehaui&m had not faltered—he writes:— Tho last 20 years have seen a steady; increase in tho percentage of machinedrawn milk in our cheese- factories, arid this has synchronised with thq increasing occurreoco of openness. Tho sugges« tion is therefore made that machine* drawn milk 13 uot identical with'handdrawn milk, and that hero again v/o have a cause which contributes ' itg quota the defect of openness. Ev ( ery cheesemaker of the old school will affirm that he never experiences to-day tho fast vats common", to; former times, and he will also maintain that slow vats so common at present were unknown in. the "good old days." Such asertions would have little merit if scientific.evidence could not be Adduced in., their favour or if a rational explanation could not be. found for the1 claims as ..stated, IDEAL FOR CHEESE-MAXINCJ. In the first place,' scientific w6rkers familiar with the microscopic appearance of cheese factory milk will safely; maintain that there is' a. readily lefcognisable difference ' between uncooled hand-drawn milk and machine-drawn milk, and this difference* is all the more recognisablo if the milk is iucubatCii at a warm temperature for a number of hours. It is especially' true that uucooled night's milk" during tho hot summer months is most distinctive. If deal* conditions are observed during milking, hand-drawn milk contains' a large -preponderance of pure lactic bacteria, and, if those develop during a vrarm night, they will rapidly outnumber and suppress other varieties. As a consequence clean, hand-drawn -night's milk showi a uniform distribution of lactic diplococci and short chains of streptococci under the microscope, and other types are rarely encountered. Such milk is ideal for cheesemaking, and, in fact, has already passed through a species of ripening period similar to that advocated in the factory. On tho other hand, machine drawa milk nnder poor conditions may contain innumerable types of bacteria, most of which, flourishing inside closed pipes and rubbers away from the action of the air, are putrefactive in nature. Th« milk thus becomes infected with the germs common to the interior of the machino and cans, and may show a comparatively low proportion of true lac« tic types. Even where grossly insanitary conditions do not exist, it is safe to say that all machines contribute some measure of infection, and that the types are largely deleterious to the best cheese-malting. CONDITIONS HOSTILE TO CLOSENESS. Here, then," wo have an explanatioa of tho distinction between old time and modern New ' Zealand ; cheesemaking. Past vats wcro common when there was a.higher proportion of-hand milk, whea a fairly largo bacterial population was present, the majority of wtyieh were lactics, and when the night's milk had passed through a ripening period sufficient to ensure, in the summer months at least, % regular and rapid development of1. acid. Under such ■ conditions acidity in the ,curd was assured, and the cheesemaker could make' a -reasonably close cheese by attention to the. body developed during the day. Nowadays machine drawn milk is either practically free from bacteria, or else is infected with putrefaetivo germs or other types which ten<J to suppress the activity of the starter culture. The period of holding the evening's milk overnight is not - a ripening period, but is an opportunity; for the multiplication of such undesir. able types as are present. Hence in the factory acid is retarded in tho morning, or fades out in th» afternoon, thus preventing tho 'cheesemaker from securing that nice relation, ship between body and full acid development which ensures closeness in the final cheese. , , It is an impracticable remedy to sugx gest a return of universal handmilking-, but it is not impossible to insist upoa the institution of universal and compulsory milk grading in order to- ensure that all milk is reasonably free from deleterious bacteria. A ripening period with inoculation by appropriate starter cultures in the factory would then supply the necessary lactic bacteria and furnish-tho condition essential to regular acid development and consequent closeness 'of texture.