Physical Chemistry of Foods

103 times 0.01%¼ 10 %of the aqueous phase would have been contaminated with
yeasts, which is not negligible.
This is only a crude reasoning. Moreover, it is not quite correct, since for such
a large contamination, the chances that a large droplet becomes contaminated with
more than one yeast cell is not negligible. Nevertheless, it illustrates the importance
of using the appropriate type of average, as well as the usefulness of obtaining a
reasonably narrow droplet size distribution in butter and margarine.

Question 2

The following raw size classification of the droplets in an o/w emulsion is given:

Size classi(mm) Ni(in 10^4 mm^3 )

<0.5 7

0.5 – 1 20

1–1.5 51

1.5 – 2 47

2–2.5 33

2.5 – 3 18

3–4 18

4–5 8

> 53

Calculate

The number frequency distribution

The volume frequency distribution

d 10 (1.97mm)

d 30 (2.49mm)

d 32 (3.11mm)

The volume fraction of oil (0.17)

The specific surface area (0.32mm
^1 ¼0.32 m^2 /ml)

Approximate results are given in brackets. Why approximate?

9.4 RECAPITULATION

Structure. Virtually all foods have a complicated composition, and
the great majority of those also have a distinctphysical structure, adding to
the complexity. In other words, most foods are dispersed systems, in which