Cheese Composition for Optimal Curing
Cheese composition is critical to yield optimization, and both flavour and texture development. This section gives some detail on several critical composition parameters, with special reference to Cheddar cheese. New Zealand export Cheddar cheese is all graded by composition analysis as indicated in Figure A on the right. Figure B on the right indicates the ranges which are typical of good Canadian Cheddar.
- Moisture: higher moisture means faster ripening which means more potential for off flavours and over ripening.
- water activity (aw) decreases with age because ripening results in many soluble breakdown products of acids, sugars, proteins and lipids
- fresh Cheddar aw = 0.98 which is conducive to most bacteria
- aged Cheddar aw as low as 0.88 which is too low for most bacteria
- MNFS is a better index of cheese ripening potential than % moisture
- Optimum MNFS depends on expected date of maturity and curing temperatures:
examples for Cheddar: 100C, 6-7 months MNFS = 53%
100C, 3-4 months MNFS = 56%
- MNFS is controlled mainly by pH at dipping and cooking treatments. Subsequent curd treatment such as cheddaring and salting also influence MNFS
- MNFS is also influenced by FDM. Other conditions being kept constant, MNFS increases with increasing FDM, because fat inhibits syneresis.
- Determines rate of acid development during pressing and early curing and, therefore, influences the minimum pH
- Affects bacterial profile, eg., high S/M will discourage contaminating bacteria such as coliforms.
- Critical to rate of proteolysis and the type of protein derived flavours
- Acceptable range is broad (3.6 - 6.0), fortunately because S/M varies widely even within a single cheese.
- Salt uptake is affected by quantity of added salt, size of curds, moisture content of curds, and acidity
- Higher fat restricts syneresis, so MNFS tends to increase with FDM
- Fat shortens and softens cheese texture because the fat globules physically disrupt the protein matrix.
- Adjusted by milk P/F (See Treatment of milk for cheese making)
- The pH profile is the single most important trouble shooting tool. Critical points are: cutting, draining, milling, 1 day and 7 days
- Most cheese including Cheddar should reach a minimum pH of 5.0 to 5.1 during the first week after manufacture; obtaining a final pH in this range is greatly helped by increased buffer capacity of milk proteins in the pH range 5.4 - 4.8.
- Factors determining the pH at one day are amount of culture, draining pH, washing, curd treatment such as cheddaring and salting.
- Draining pH is most important to cheese texture and also determines residual amounts of chymosin and plasmin in the cheese.
- pH increases with age due to release of alkaline protein fragments. This is especially true of mould ripened cheeses. Camembert pH increases from 4.6 to 7.0, especially on the surface.
- Increasing pH during curing encourages activity of both proteases and lipases.