Stephany Ayoubi
Background: Milks and cheeses are typical dairy products used in household to make common dishes such as mac & cheese, cheesecake and creamy soups. Among dairy products is milk, an oil in water emulsion. Milk is composed primarily of water, proteins like casein and whey and carbohydrates like lactose. The fat content varies depending on type of milk. Amount of fat can influence flavor and texture of final product. The casein protein found in milk, makes up 80% of the protein content, requires acidic conditions to be formed and curd and is susceptible to heat coagulation. Whey makes up the other 18% of protein in milk, and it’s composition consists of lactalbumin and lactoglobulin. Whey is ultimately the liquid that drains from casein and is used as an emulsifier, foaming agent and gelling agent. Milk is processed by either homogenization or pasteurization. Homogenization will pump the milk under high pressure through small openings to break up fat globules. This process will increase flavor and viscosity since fat is evenly distributed in milk. Pasteurization is using high temperatures to prevent spoilage and destroy pathogens. Both homogenization and pasteurization account for flavor since fat is redistributed to mixtures. Film and scum formation are caused by protein coagulation, precipitated calcium salts and fat globules which concentrate when milk is heated in an uncovered pan and water evaporates. As water evaporates, pressure builds up beneath the film which causes an abrupt boiling over of milk (2).
Materials and Methods:
Macaroni & Cheese involves a series up steps to create. First, the ½ cup of macaroni is boiled in water until al dente and then drained. Meanwhile, 1 tablespoon of flour, ⅛ teaspoon of salt, a dash of white pepper and ⅛ teaspoon of dry mustard are combined in saucepan in which
⅔ cup of 2% fat milk is slowly whisked in. After the liquid and dry ingredients have been combined, heat the mixture over moderate heat and stir constantly until thickened. Mix in ⅓ cup shredded low fat cheese, ¼ tablespoon Worcestershire sauce and ¼ tablespoon grated yellow onion. In an oven safe dish, combine macaroni and sauce together and sprinkle ⅓ cup of shredded lowfat cheese. Bake this combination for 30 minutes uncovered and at 350 degrees fahrenheit in the oven.
The mini low fat cheesecakes are made in layers. The first layer is a crust made of ¼ cup of graham cracker crumbs placed in a greased (using nonstick spray) muffin tins. The next layer is where the cheese is added. Beat 4 ounces of lowfat cream cheese for a minute. Then, add 3 tablespoons of sugar and beat for an additional minute. The mixture can beat for 3 more minutes after 1 egg white, 1 teaspoon of skim milk, 1 teaspoon of flour, ½ a teaspoon of vanilla and 1 tablespoon of non fat yogurt is added. This filling can be poured over the graham cracker crust and then baked in the oven at 350 degrees fahrenheit for 20 minutes. Refrigerate until cold and then serve the cheesecake (1).
Observations:
Product Appearance Consistency Flavor
Macaroni and More Yellow Smooth Creamy Cheese Regular Creamy More Cheesy Cheddar Cheese
Macaroni and Browned Top Not as Creamy Slightly Bland Cheese Low Fat More Grainy Cheese Cheddar Cheese*
Macaroni and Crisperiest Creamiest Synthetic Cheese Velveeta Edgiest Rubbery Cheese Most Yellow
Macaroni and Light Yellow Chewy More Flavorful Cheese Sharp Smooth Cheesey & Salty Cheddar Cheese
Mini Cheesecakes White, Slightly Smooth More palatable Browned Very Creamy Slightly golden surface Sweeter
Low Fat Mini White Creamy Bland Cheesecakes* Smooth Tender Crust Slightly Tart
Cream of Broccoli Light Green Heavy Salty Soup Half & Half Creamy Fat flavor Chucky Green
Cream of Tomato Red brownish sol Thick sol Herb, Basil, Tomato, Soup 1% Salty
Results:
In the low fat mac & cheese, lowfat milk and low fat cheese were used. The process involved using a solid cheese that was combined with milk and other ingredients to make a liquid. This liquid was creamy, thick and and had a cheesy flavor. The worcestershire sauce which was added, created a distinct and palatable taste before it was cooked. After the mac and cheese was baked, the onion and worcestershire sauce seemed to compliment the dish. The baked product was slightly browned at the surface. The surface was not only browned but also seemed to have formed a slightly grainy film after baked. Velveeta seemed to have little to no grainy film on the surface and was simply creamy but had a rubbery and artificial taste.
In the low fat cheesecake recipe, low fat cream cheese was used to as the main component. Sugar was also added, which enhanced the sweetness of the recipe. The full fat cheesecake was more sweet and the low fat version seemed more bland. Surprisingly, yogurt was added which provided a very tangy taste to the batter and once baked became less distinct.
The surface of the cheesecake was white and the texture inside was smooth with a slight crumble. The full fat recipe had less of a crumble and was more tender. Overall, the cheesecake recipes seemed to vary by surface color, creaminess, and sweetness.
The two soups varied by fat content as well. The broccoli soup variation was cooked with half and half. The tomato basil soup was cooked with 1% fat milk. Both seemed to be very creamy.
The basil tomato soup had a more fresh flavor due to added herbs such as basil. Lastly, the broccoli soup had a dense creamy taste.
Discussion:
The milk and cheese combination is a whey and casein combination. The combination of the sugars in the dairy, lactose, and the proteins, whey and casein, created a maillard reaction.
This reaction was shown on the surface of the cheesecake, leaving a slightly browned surface on the full fat mini cheesecake. The low fat cheesecake was not brown at all. This is because, one of the functions of fat is browning. With not as much fat, browning is less possible. Lactose is the least soluble and least sweet sugar which is why adding sugars to desserts is important to get the right sweetness desired by the consumer. Both cheesecakes had a similar sweetness intensity. The addition of acid, to the low fat cheesecake created a paste instead of a curdle due to the slow addition of the flour, cream cheese and milk.
The macaroni variations seemed quite similar until closer examinations. One of the main differences seemed to be color. Velveeta had the brightest yellow color. Velveeta is a processed cheese with additives such as coloring agents which affect visual observations in this lab. The most bland in color was actually the sharp cheddar cheese variation. The difference between sharp cheese and regular cheese is a matter of aging. The more sharp the more a cheese has been aged. Typically, the more a cheese has been aged the more flavor compounds produced.
So although the sharp chedder may have seemed lighter in color than the regular cheese variation, it is more likely to have more flavor. This could also explain why the low fat variation was the least palatable. Fat’s main function is to provide flavor, which accounts for the unpalatable low fat variation (2).
The soups had surprising results. Half and half is a far more fatdense dairy than 1% milk that was used in the tomato soup. Therefore, the broccoli soup was expected to be more creamy than the tomato soup. However, in the tomato soup a roux was created using oil, flour and scalded milk. The crushed tomato used in the soup is a source of acid and acids typically have the effect of curdling and coagulation when combining with a dairy such as milk. However, a roux is created to prevent the damage resulting in a very creamy and smooth soup. Overall; the recipes that were most liked were mac & cheese the regular cheese, full fat cheesecake, and cream of broccoli soup. Those recipes all had a higher fat content which forms the positive correlation between fat content and flavor.
Citation:
1. Lab Manual (pp. 147156). (2014) Milks and Cheeses. New Brunswick: Rutgers. 2. Tangel, Barbara, R.D. "Milk and Dairy Products." Lecture 19. Rutgers University, New
Brunswick. 14 Nov. 2014. Lecture.