Dairy Ingredients for Food Processing

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Chapter 4

Processing Principles of Dairy Ingredients

Arun Kilara

Introduction

Milk is a highly perishable biological fl uid.
Its composition and the factors that contrib-
ute to variability in the composition have
been discussed in Chapter 2. Milk from many
farms is collected in tankers two to three
times a week and delivered to a processing
facility (also known as a dairy plant or
factory), where it is stored and processed
further to make the appropriate products for
which the dairy plant is designed.
Product safety is a major concern in dairy
processing. This chapter discusses the regu-
lations for the production and storage of milk
at the farm, transportation from the farm to
the factory, and the holding and processing
on the factory premises. Regulations also
apply for standardized food products that
must meet compositional requirements as
well approved ingredients and processes. In
addition, product manufacturers may have
internal standards for ensuring the quality of
product aspects that are important to the con-
sumer including taste, texture, odor, fl avor,
mouth feel, color, and keeping quality.

From Farm to Factory

Milk is produced on the farm under strict
guidelines that determine its grade (see

below). In 2007 the total milk production in

the United States was 83.4 billion kg (185.6

billion pounds). Farms with 200 to 500 milk

animals accounted for approximately 17.5%

of the total milk produced. Farms with 50 to

100 cows and those with more than 2,000

cows accounted for 17.4% and 15% of the

total milk production, respectively. Also in

2007, 9.158 million cows were tended by

78,295 production units, which results in an

average of 128 cows/farm. The general trend

is toward fewer farms with larger herd sizes.

Farms use milking parlors of various

designs and the milking interval is unequal.

Cows are milked twice/day; however, a small

minority milk three times/day. The milk from

each animal is weighed and mixed with milk

from other animals in the batch of cows being

milked. Milk temperature immediately after

milking is approximately at the body tem-

perature of the cow (38 ° C/101 ° F). Many

mesophilic microorganisms can grow at this

temperature; therefore, warm milk is cooled

rapidly to minimize microbial growth.

Cooling is commonly achieved by plate heat

exchangers. Milk from several days ’ milking

is collected in insulated tanks called farm

bulk milk tanks (Figure 4.1 ).

Milk collection occurs more frequently on

the farm as the number of cows in the herd

grows and the numbers of dairy farms shrink.

For example, a tanker is dispatched every 45

minutes to Arizona dairy farm milking 7,000

cows twice/day. Smaller farms may use ice

bank building tanks. For achieving the best

Dairy Ingredients for Food Processing edited by
Ramesh C. Chandan and Arun Kilara
© 2011 Blackwell Publishing Ltd.