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4.5.4 Natamycin

Natamycin (Figure 4.14), formerly know as pimaricin, is a polyene
macrolide antibiotic produced by the bacteriumStreptomyces natalensis.
It is a very effective antifungal agent as it binds irreversibly to the fungal
sterol, ergosterol, disrupting the fungal cell membrane leading to a loss
of solutes from the cytoplasm and cell lysis. Natamycin is poorly soluble
in water and is used as an aqueous suspension for the surface treatment
of cheeses and sausages to control yeast and mould growth. It has some
advantages over sorbate in this respect since it remains localised on the
surface of the product, is not dependent on a low pH for its activity and
has no effect on bacteria important in the fermentation and maturation
of such products.

4.5.5 ‘Natural’ Food Preservatives

The uncertainty voiced by consumer organisations and pressure groups
over the use of food additives including preservatives has already been
referred to. One approach to reassuring the consumer has been recourse
to methods of preservation that can be described as ‘natural’. The whole
area though is riddled with inconsistency and contradiction; it can be
argued that any form of preservation which prevents or delays the
recycling of the elements in plant and animal materials is unnatural.
On the other hand there is nothing more natural than strychnine or
botulinum toxin. Smoking of foods might be viewed as a natural method
of preservation. Its antimicrobial effect is a result of drying and the
activity of woodsmoke components such as phenols and formaldehyde
which would probably not be allowed were they to be proposed as
chemical preservatives in their own right.
The use of natural food components possessing antimicrobial activity
such as essential oils and the lactoperoxidase system in milk (see Section

O O

OH

NH 2

HO

H 3 C

O

HOOC

HO

OH

OH

O

O

O

CH 3

Figure 4.14 Natamycin

Chapter 4 107