Ricotta Cheese

Overview

Ricotta is a heat/acid precipitated cheese that can be made from whole or skim milk. A related product called ricotone is made in a similar fashion from a mixture of milk and whey. Raw milk can be used as the starting material for the production of ricotta cheese as the heat treatment during curd formation more than meets the heat requirements for pasteurization. In the first step of the process acid is added to the milk to lower the pH to 5.9-6.0. The acid added can be as a result of starter culture growth or the direct addition of acid whey or a food grade acid such as acetic or citric. The mixture is then heated to 80-85C, for 15-30 minutes.

This heat treatment, combined with the effect of the acid causes the precipitation of the curd. Exposure to such a high heat load results in denaturation and disulfide bonding of some of the whey proteins, particularly b-lactoglobulin, onto the surface of the casein micelles. When the curd is formed, it is composed of both casein and whey proteins, unlike a conventional curd which is almost all casein. The textural properties of the ricotta curd also differ from a conventional rennet/acid curd in that the ricotta curd is loosely aggregated and entraps air. This results in a curd with a relatively low density that will float on the top of the cheese vat, a property characteristic of ricotta cheesemaking. Proper control of the pH and the level of agitation are necessary to ensure that the curd floats and does not sink. The floating curds are collected and allowed to drain for 4-6 hours in a cold room and then the cheese is ready to consume. Ricotta is an unripened cheese with the heat treatment used to coagulate the proteins destroying the starter culture. The lack of ripening and the absence of rennet enzyme limit proteolysis and the finished cheese has a very mild flavour.

Ricotta cheese has a high moisture content and fairly high final pH, and accordingly a short shelf life. Inclusion of the whey proteins into the curd results in both a high protein yield and high protein quality for ricotta cheese. However, due to the high moisture content, the actual concentration of protein is lower than in many harder cheeses.

Ricotta cheese is used as an ingredient to add sensory appeal, mild flavour, and nutritional value to foods. Both part skim and whole milk versions of ricotta cheese provide a source of calcium, phosphorus, zinc, riboflavin, vitamin A and vitamin B12 in each serving.

Ricotta cheese is a soft and creamy cheese with a light texture and mild, slightly sweet flavour. The colour of ricotta cheese is off white.

Composition

Ricotta cheese is made from milk with two additives. Polysaccharide stabilizers (e.g. guar gum, xanthan gum) are added to the milk in order to prevent excess foaming during the curd formation step. A small amount of salt is also included to enhance the flavour of the cheese.

Typical compositions for ricotta cheese are as follows:

Variety	Moisture	Protein	Fat	Carbohydrate	Ash
Whole milk Ricotta cheese	72%	11%	13%	3%	1%
Part skim Ricotta cheese	74.5%	11.5%	8%	5%	1%

Lipid profile (g/100g of cheese):

Variety	Saturated fatty acids	Monounsaturated fatty acids	Polyunsaturated fatty acids	Cholesterol
Whole milk Ricotta cheese	8.3	3.6	0.4	0.051
Part skim Ricotta cheese	4.9	2.3	0.3	0.031

Vitamin and Mineral content (mg/100 g):

Vitamins and minerals	Whole milk Ricotta cheese	Part skim Ricotta cheese
Sodium	89	125
Potassium	105	125
Calcium	207	272
Phosphorus	158	183
Magnesium	11	15
Zinc	1.16	1.34
Iron	0.38	0.44
Copper	0.021	0.034
Manganese	0.008	0.010
Selenium	0.0145	0.0167
Vitamin A	0.134	0.113
Thiamin	0.013	0.021
Riboflavin	0.195	0.185
Niacin	0.104	0.078
Vitamin B6	0.043	0.020
Folate	0.012	0.013
Vitamin B12	0.00034	0.00029
Pantothenic Acid	0.213	0.242
Vitamin C	0	0
Vitamin E	0.350	0.214

In terms of microbiological standards, all cheeses made from pasteurized milk must contain fewer than 100 Escherichia coli per gram and fewer than 100 Staphylococcus aureus per gram.

Application Based on End Use

The delicate texture and flavour of ricotta cheese make it particularly suitable for use as a filling in products such as pastas and desserts. Ricotta has similar properties to, and can often be substituted for cottage cheese.

Ricotta cheese can be used as the filling in a variety of pasta dishes. The lightness of the cheese provides a pleasant texture and the mild flavour of the cheese compliments the flavour of the pasta sauce. Spinach is frequently paired with the ricotta cheese in this application.
The light colour of the ricotta cheese as a pasta filling or as a layer in lasagna is an attractive contrast to dark pasta sauces.
The creamy texture of ricotta makes it suitable for use in spreads and dips.
Ricotta can be used to compliment the flavour and texture of eggs in scrambled eggs, omelettes and soufflés.
Ricotta cheese can be incorporated into products such as breads, muffins and pancakes to provide moistness. The cheese will also contribute to the browning of the products.
Ricotta cheese can be melted into cream sauces to provide viscosity.
Ricotta cheese can be sweetened and used as the filling in desserts such as cannoli. Again the flavour and texture of the cheese are the important factors.
Ricotta can be incorporated into products such as cheesecakes to provide a lighter texture.

Functional Properties

Ricotta has a mild, sweet flavour that compliments many other ingredients.
Ricotta has a light texture. This texture is good on its own, for example as a pasta filling, or ricotta can be used in place of other cheeses to give a lighter texture, for example as a partial replacement for cream cheese in cheesecake.
Ricotta cheese has a high moisture content. Incorporating ricotta into baked goods will help keep the product moist.
Melted ricotta can be used to add viscosity to soups and sauces.

For more information on cheese, please visit the University of Guelph’s Dairy Science and Technology Web site.