Part 17 (1/2)

Our knowledge regarding the exact nature of these indefinite faults is as yet too inadequate to enable many of these undesirable conditions to be traced to their proper source; but in many cases the taints observed in a factory are due to the abnor unpleasant or even putrid odors Most of them are seeded in the milk before it comes to the factory and are due to careless manipulation of the ain access to theto unclean conditions of one sort or another Sometiorous treatment, but often they pass on into the cheese, only to detract from the market value of the product Most frequently these ”off” flavors appear in cheese that are cured at too high temperatures, say above 65 F

~”Gassy” fermentations in cheese~ One of the worst and at the sa is where the cheese undergoes a feras is recognized by the appearance either of spherical or lens-shaped holes of various sizes in the green cheese; often they appear in the curd before it is put to press Usually in this condition the curds look as if they had been punctured with a pin, and are known as ”pin holey” curds Where the gas holes are larger, they are known as ”Swiss holes” from their resemblance to the noras is abundant, these holes are restricted in size Often the foras may be so intense as to cause the curds to float on the surface of the whey before they are removed Such curds are known as ”floaters” or ”bloaters”

If ”gassy” curds are put to press, the abnoras causes the green cheese to ”huff” or swell, until it33

In such cases the texture of the cheese is greatly injured, and the flavor is generally iassy es may occur at any season of the year, but the trouble is most common in summer, especially in the latter part

This defect is less likely to occur in cheese that is well cheddared than in sweet curd cheese When acidity is produced, these gassy ferood cheddar the body is so close and fires

In Swiss cheese, which is essentially a sweet curd cheese, these fere holes are formed in abundance (blahen), the trouble reaches its as holes are very numerous and therefore small it is called a ”nissler”

So when it is said to be ”blind” or a ”glasler”

[Illustration: FIG 34 Block Swiss cheese showing ”gassy”

fermentation]

One method of procedure which is likely to cause trouble in Swiss factories is often produced by the use of sour, fermented whey in which to soak the natural rennets Freudenreich and Steinegger[209] have shown that a much more uniform quality of cheese can be made with rennet extract if it is prepared with a starter made from a pure lactic fered to various sources, such as a lack of aeration, iases, etc, but in all these cases it was nothing more than a surmise Very often the milk does not betray any visible symptom of fernized until the process of cheese-ical standpoint have, however, thrown ht on this troublesoas, either in the curd or after it has been put to press, is due entirely to the breaking down of certain elear of erms This trouble is, then, a type fermentation, and is, therefore, much more widely distributed than it would be if it was caused by a single specific organisly at least, in almost all milks, but are nor theh yeasts and allied germs are often present and are likewise able to set up ferar is decoive off CO_{2} and H, and in sos[210] found a lactose-splitting yeast in a severe outbreak of gassy cheese in a Swiss factory In this case the gas did not develop until the cheese were a feeeks old In severe cases the cheese actually cracked to pieces

According to Guillebeau, a close relation exists between those germs that are able to produce an infectious inflammation (mastitis) in the udder of the cow and soas evolution

If pure cultures of these gas-producing bacteria are added to perfectly sweet milk, it is possible to artificially produce the conditions in cheese that so frequently appear in practice

~Treatment of ”pin-holey” curds~ When this type of fer the manufacture of the cheese, the maker can control it in part within certain limits These methods of treatment are, as a rule, purely mechanical, as when the curds are piled and turned, and subsequently ground in a curd as has been forced out, the curds are then put to press and the whole mats into a compact mass

Another ical principles is the addition of a starter to induce the forrowth of the lactic-acid bacteria, the gas-producing species do not readily thrive Another reason why acid aids in repressing the developas is that the curd particles are partially softened or digested by the action of the acid This causes theether ular ment

Another method that is also useful with these curds is to easeous fer the cheese will very often restrain the production of gas Tendency to foras in Edam cheese is controlled by the addition of a starter prepared froe hich is caused by the developanis the curds to re bacteria contained therein Care must be taken not to carry this too far, for the reanisms to thrive[211]

The temperature at which the cheese is cured alsoteanisms develop rapidly; therefore more trouble is experienced in summer than at other seasons

If assy” developeneral supply, it would be possible to eliminate the source of the entire trouble To aid in the early recognition of such ht to the factory, ferreat value The use of this test in the hands of the factory operator often enables him to detect the exact source of the trouble, which le patron

~”Fruity” or ”sweet” flavor~ Not infrequently the product of a factorywhat is known as a ”sweet” or ”fruity” flavor This flavor resembles the odor of fermented fruit or the bouquet of certain kinds of wine It has been noted in widely different sections of the country and its presence bears no relation to the other qualities of the cheese The cause of this trouble has recently been traced[212] to the presence of various kinds of yeasts

Ordinarily yeasts are rarely present in good cheese, but in cheese affected with this trouble they abound The addition of starters made from yeast cultures resulted in the production of the undesirable condition

~Mottled cheese~ The color of cheese is sometimes cut to that extent that the cheese presents a wavy or mottled appearance This condition is apt to appear if the ripening teer quantities of rennet used than usual The cause of the defect is obscure, but it has been demonstrated that the sa soy of the trouble has not yet been worked out, but the defect is undoubtedly due to an organis cheese It has been claimed that the use of a pure lactic ferment as a starter enables one to overcome this defect

~Bitter cheese~ Bitter flavors are so process is carried on at a low temperature in the presence of an excess of th of time

Guillebeau[213] isolated several forms from Emmenthaler cheese which he connected with udder inflammation that were able to produce a bitter substance in cheese