Dairy Ingredients for Food Processing

Dairy Ingredients in Dairy Food Processing 467

well as their spores. The product is refriger-

ated to retain freshness.

A fl ow chart for manufacturing long - life

rice pudding is given in Figure 17.10.

Quality Control Essentials

During the manufacturing processes, it is

imperative to ensure optimal cooking of

the starch by appropriate heating of the

pudding mix. If the starch is undercooked,

its appearance is cloudy, its texture is thin,

and the viscosity is too low. On the other

hand, overcooked starch loses viscosity and

acquires cohesive long texture. Optimally

cooked starch is clear and maintains stabil-

ity with good viscosity and heavy - bodied

short texture.

The processing conditions should be opti-

mized depending on the UHT equipment

being used. Preheating is not required in

direct steam heating systems and in scraped -

surface heat exchangers, whereas for plate

heat exchangers preheating at 65 ° C to 76 ° C

(149 ° F to 169 ° F) (no holding period) is

recommended. Homogenization is not rec-

ommended for direct steam heating equip-

ment. For plate heat exchanger equipment,

homogenization at 20 kg/cm^2 helps to avoid

sandiness in the product. Similarly, homog-

enization at 75 kg/cm^2 for scraped - surface

heat exchangers is given (Rapille and

Vanhemelrijck, 1998 ). According to the

authors, effective heat treatments are also

specifi c for the type of processing equipment.

In general, the optimum heat treatment for

direct steam heating equipment is 142 ° C

(288 ° F) for 5 seconds, a plate heat exchanger

requires 140 ° C (284 ° F) for 10 seconds, and

scraped - surface heat exchanger equipment

needs 138 ° C (280 ° F) for 5 seconds.

Sensory evaluation should be performed

on fresh and stored samples for appearance,

fl avor, and texture. A score sheet should

be developed and the terms used to describe

the attributes should be fully understood

by the sensory panel. Any free liquid on

Batch process procedure. In a typical
procedure, rice pudding is prepared by
immersion of pre - soaked rice (5% to 6% by
weight of milk) in simmering milk followed
by addition of sugar (6% to 8%) and heating
the mixture further until the rice softens and
shows signs of gelatinization, leading to sub-
stantial thickening. Rice grains (broken or
whole) are exposed to saturated steam at a
pressure higher than atmospheric pressure
(greater than 0.03 bar) in an autoclave for
suffi cient time to gelatinize a major portion
of the starch. The rice grains are then mixed
with milk.
The production process for in - can steril-
ized creamed - rice dessert involves short grain
rice releasing starch on cooking (Aneja et al.
2002 ). Homogenization of milk improves the
product quality. Gradual heating periods and
agitation are necessary during autoclaving to
prevent localized overheating. The product
exhibits some browning and age thickening
during its shelf life of 12 months. Long grain
or medium grain rice, milk, sugar, eggs,
vanilla, and salt are added to a batch cooker.
Heat processing involves a temperature of
88 ° C (190 ° F) and holding period of 30 to 40
minutes, with gentle stirring. The product is
hot - packaged in a clean environment, vacuum
sealed, and cooled to 4 ° C to 5 ° C (39 ° F to
41 ° F). The extended - shelf - life product is
marketed refrigerated and has a shelf life of
60 to 75 days.
UHT process procedure. Rice pudding
also has been manufactured employing a
scraped - surface heat exchanger. Rice and
milk are pumped into the scraped - surface
heat exchanger system, heated to 115 ° C
(239 ° F), held for 26 minutes in a holding
tube, and then cooled to 80 ° C (176 ° F) in
another cylinder. The rice pudding is trans-
ferred to a sterile buffer tank, and then dis-
pensed into form - and - fi ll plastic containers
under aseptic conditions. This process pro-
vides a better shelf life by subjecting the
product to a more rigorous heating regime
that kills the microbial vegetative cells as