Agriculture Reference
In-Depth Information
in two hours following which the temperature is raised to 20-21°C and held for
two hours. This causes the low melting point fractions (short chain and unsaturated
triacylglycerols) to melt. The cream is then cooled to 16°C and held briefl y at this
temperature, then cooled back to 8°C and held overnight. The controlled
temperature cycling of cream causes the low melting point triacylglycerols to
recrystallise around crystals of high melting point lipids which act as nuclei. This
has the benefi t of improving the spreadability of the fi nal product. In the phase
inversion stage, cream is passed through a continuous buttermaker in which cream
is churned, or beaten mechanically causing the milkfat globule membranes to
rupture. Crystallised milkfat is released and coalesces to form butter while the
aqueous phase, which is rich in milkfat globule membrane phospholipid, forms
the by-product, buttermilk. The butter is then worked mechanically to distribute
water droplets and, at this stage, an additive in the form of salt may be dispersed
through the butter to act as a preservative. The composition of unsalted and salted
butters is given in Table 17.5. The production of lactic butter may be based on the
fermentation of cream prior to buttermaking using lactic acid bacteria (LAB),
which is a method employed in some European countries. In contrast, the direct
acidifi cation method developed by NIZO in the Netherlands is based on the
addition of natural lactic acid and a diacetyl producing bacterial culture to sweet
cream butter (Ranken et al . 1997).
Dairy spreads
Historically, the dairy industry's principal spread product has been butter.
However, as margarines have been developed and improved to satisfy more
precisely consumers' needs (e.g. a product that spreads on baked goods easily
from the fridge), the dairy industry has innovated to retain as much as possible its
share of the spreads market. This has led to a range of products containing blends
of milkfat and vegetable fats which, to some extent, mimic margarines in their
functionality and eating qualities. Of course, margarines are made from vegetable
fat and contain no milkfat, which is why many margarines incorporate buttermilk
solids thus to possess some of the superior fl avour notes characteristic of butter.
One of the earliest blended milkfat and vegetable fat products to reach the
marketplace was Bregott, a Scandinavian product of 80% fat content of which
70-80% was milkfat and 20-30% vegetable fat (usually soya oil). Bregott is made
￿ ￿ ￿ ￿ ￿
Table 17.5
Composition of salted and unsalted butters
Component
Salted butter (g/100g)
Unsalted butter (g/100g)
Total lipid
81.11
81.11
Protein
0.85
0.85
Carbohydrate, by difference
0.06
0.06
Ash
2.11
0.04
Water
15.87
17.94
Source: Adapted from US Department of Agriculture National Nutrient Database for Standard
Reference (www.nal.usda.gov/fnic/foodcomp/search/).
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