196 UNIVERSITY OF WISCONSIN STUDIES 
Trial I 
Material Bacteria per c. c. 
CREA: ccoirorccescaclstardnawage den aantesgaietientty Waves Hie nd eacdigibin ini s 9 HLA 720,000 
Mix heated but not held.......... cece eee eee eens 156,500 
Mix pasteurized 142 degrees F., 20 minuteS....-...+-seeeeeee eran 1,545 
Pasteurized mix through homogenizer without pressure......... 2,025 
Pasteurized mix through homogenizer, 170 Kg. pressure.......- 4,250 
Frozen i€C@ CLEAN 2... cece eee eee ener e ence nee sees tenet 5,900 
Hardened ice cream..........c.e cree cere neers ities diestvarete neeoele Soa ae 2,250 
Trial IL 
Material Bacteria per c. e. 
CLOAN. sce dededis ap sa deletetbcinane ae te ae ea eaeKsecebaaeh Ria sone pie suena ME Hie as 5,200,000 
Mix before: heating: .e1 a6 cc veneraycecs celeseiong ge Se ws Merisoner crea o's onl nel 1,300,000 
Mix pasteurized: os... cc:osaecd 4 24 be Stee tandnes 4 seine Raitceiorets Sameer 170 
Pasteurized mix through homogenizer with pressure............. 375 
Frozen! ACC CRO AI s4 aa tiered aaheheeanl hers 5 nd aiheaendlgiisie sng aed 7,950 
‘Trial IIT 
Material 
QC ATT asensigoas edb oes-hinisdyond SeueisaeMaA eae uae ASCE IT BE Me Uae See eres 
Mix before heating........... 0. ese c eect e ence eee eee tee e rece snes 
Mix pasteurized 145 degrees F., 20 minutes...............0.00 eee 
Pasteurized mix through homogenizer with pressure. 
rozeni ice cream owwasdiiens oy alewame teas 1a oe ie Reet 24 Be 
One of the peculiar changes shown in the data is the con- 
siderably smaller number of bacteria in the mix than in the 
cream. This relationship has been consistently obtained, and 
is likely due, in part at least, to the plasmolyzing action of 
the sugar. The volume change may play a part, but the very 
great reduction encountered in most instances cannot be ex- 
plained in that way alone. 
Revation or Ick Cream ‘to Pusiic Heavre 
The real reason for the concern regarding the bacteriology 
of ice cream is that this product is more or less frequently 
responsible for human disease. The diseases caused by ice 
cream can be divided into two groups: poisoning and infeec- 
tious disease. 
The eases of poisoning from ive cream are well advertised 
by the newspapers and it is very probable that ice cream gets 
more than its just share of the blame in this connection. It 
seems, moreover, that the most of the ice cream that is the 
cause of cases of poisoning is ice cream manufactured in homes 
or in small poorly equipped factories. Tee cream mixes made 
