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Abstract
Frozen yoghurt is a frozen dairy product in which yoghurt is
a major component. It is relatively new product that can expand the
market for ice cream makers. Aiming to improve the quality of
frozen yoghurt, this study was carried out in two parts,
- In the first one the standardized milk in the mix was
replaced by different levels of yoghurt.
- In the second part the standardized milk used in the mix
was fermented to different values of pH before mix
preparation.
Some properties and quality of the mixes and resultant frozen
yoghurt were followed. The results could be summarized in the
following:
- Specific gravity and weight per gallon of the mixes were not
affected by the yoghurt level in the mix or by the pH of added
cultured milk, but slightly increased as fruit solids was
increased in the mix.
- The mix acidity increased and the pH decreased by increasing
the yoghurt level or using low pH culture milk or by adding
fruits to the mix.
- As the yoghurt level increased in the mix or the pH of added
cultured milk decreased or fruits were added. The corresponding
values of viscositv was increased. -’
- Freezing point of the mixes was not affected by the yoghurt
level in the mix or by the pH of added cultured milk, but adding
fruits decreased the freezing point.
- The overrun of frozen yoghurt was decreased by increasing the
yoghurt level in the mix or decreasing the pl-I of added cultured
milk or by adding fruits. An opposite trend was recorded for
specific gravity and ’weight per gallon of the frozen yoghurt.
- The low melting rate of frozen yoghurt was related to the high
level of yoghurt and low pH of added cultured milk to the mix.
- A good quality frozen yoghurt was attained by either replacing
up to 50% of the standardized milk by yoghurt or fermenting the
standardized milk to pH 5.5-6.0. The body and texture was
smooth with good melting properties in the mouth. Addition of
fruits i.e. strawberry or mango improved the flavour quality of
flavoured frozen yoghurt.