Showing posts with label Lesson3. Show all posts
Showing posts with label Lesson3. Show all posts

Monday, March 5, 2012

Thoughts on buttermilk pancakes

I am curious to try the recipe before noted. This section made me realize how many imitation products I have consumed in the past, mainly chosen for their cheaper price. One often hears that natural is better, and this lesson puts that theory to the test. I am curious to see if I can truly appreciate a palatable difference between true cultured milks and their cheap imitations. I am most anxious to test:
  • cultured sour cream versus acidified sour cream.
  • true buttermilk
  • probiotic yogurt
As far as maple syrup, I have not liked it in the past, but I am quite certain I have never tried the real thing. I prefer honey to syrup, so maybe real maple syrup is bound to change my mind.

Buttermilk pancakes with blueberry compote

Recipe from from Bon Appétit, March 1999, as noted in http://ocw.mit.edu/courses/special-programs/sp-287-kitchen-chemistry-spring-2009/readings/MITSP_287s09_read04_pancakes.pdf


Ingredients:
  • 2 1/2 cups of all-purpose flour
  • 1/4 cup sugar
  • 2 tsps baking powder
  • 2 tsps baking soda
  • 1 tsp salt
  • 2 cups buttermilk
  • 2 cups sour cream
  • 2 large eggs
  • 4 tsps vanilla extract
  • 3 tbsps unsalted butter
  • additional butter or cooking spray
Method:
  1. Whisk first 5 ingredients in large bowl (the dry ingredients). Whisk buttermilk, sour cream, eggs and vanilla in another large bowl. Add to dry ingredients. Stir until batter is just blended but still lumpy (do not overmix).
  2. Melt 1/2 tablespoon butter on griddle over medium heat. Pour batter by 1/3 cupfuls onto griddle, spacing 2 inches apart. Cook until bubbles break on surface, about 3 minutes. Turn pancakes over. Cook until bottoms are golden, 3 minutes. Transfer to plates. Repeat with remaining batter, adding butter to skillet as needed.
  3. Serve pancakes immediately with butter and syrup/blueberry compote.  
Makes about 18 pancakes.


Blueberry compote (optional)

Ingredients:
  • 2 1/2 cups frozen blueberries, unthawed
  • 1/3 cup sugar
  • 1/3 cup water
Directions:

Combine 1 1/2 cups blueberries, sugar and 1/3 cup water in heavy small saucepan. Simmer over medium heat until berries burst, stirring often, about 10 minutes. Add remaining 1 cup berries. Cook until compote coats spoon, stirring often, about 8 minutes. (Can be made 3 days ahead. Cover and chill.) Serve warm.

Maple syrup

North American Indian tribes, notably the Angonquins, Iroguois, and Ojibways, extracted the maple tree sap long before Europeans colonized America. To the colonists, maple sugar was chaper than the tax-laden cane sugar. After the Revolution, some Americans preferred maple syrup on the moral ground that it did not require the work of slaves to produce it. Demand for maple syrup, however, declined steeply once cane and beet sugar became cheap. Today the production of maple syrup is almost isolated to the Eastern Candadian provinces and the American Northeast.

Humans make syrup in a process that mimics the bees' production of honey: Extraction of dilute juices from plants and water evaporation to concentrate the sugars. Tree syrups, such as maple syrup, are similar to honey in that the retain nearly all the original contents of the sap and are not further refined like cane sugar. The Acer saccharum maple tree produces the greatest quantity and quality of sap, and accounts for most of the syrup currently produced.

The first step in maple syrup production is the sap run. The sap is collected in the spring between the first major thaw and the burst of leaf buds. Sap production is affected by four external factors: severe winter that freezes the roots; snow cover that keeps the roots cold in the spring; extreme variation in tempreature from day to night; and good exposure to the sun. The Canadian provinces meet all of these conditions favorably. Sap runs in other trees, but maples produce the most due to a unique mechanism by which they force sugars from the previous season out of storage.

Up until the 20th century, sap was collected by punching a small hole in the tree bark, inserting a spout, and hanging a bucket to catch the sap. Modern methods have improved the efficiency of collecting the sap from multiple trees into a central holding tank. Becasue the sap consists of mainly water that must be evaporated to concentrate the sugar, it takes about 40 parts sap to make 1 part syrup. Currently manufacturers use reverse osmosis to remove up to 75% of the water content without heat. They boil the concentrated sap for flavor development and sugar concentration. Ideally, maple syrup is 65% sugars, with 62% in the form of sucrose and 3% glucose and fructose. The remaining 35% is mainly water with some malic acid and other impurities.

The flavor of maple syrup comes from sugars, acids, vanillin (a wood by-product), and the products from sugar caramelization and browining reactions. The longer and hotter the syrup is boiled, the darker the color and heavier the taste. Maple syrups are graded based on color and flavor. Garde A maple syrup is to be consumed directly whereas Grade B is used mainly in cooking. Maple syrup is expensive, so most supermarket syrups contain little or none, but rather are artificially flavored.

Sunday, March 4, 2012

Buttermilk

True buttermilk is composed of the low-fat portion of milk that remains after the cream has been churned into butter. Traditionally, its thickness and flavor develop by mild fermentation.  It has remnants of fat globules that make it an excellent emulsifier like lecithin; a characteristic that make it valuable in the preparation of finely-textured foods. True buttermilk is slightly acidic and has a subtle, complex flavor. Regrettably, it is prone to spoilage and off-flavors.
A shortage of true buttermilk after World War II led to the development of imitation “cultured buttermilk.” It is made from ordinary skim milk that is fermented.  The process follows that of yogurt, but the fermentation is stopped abruptly by rapid cooling. The gelled milk is then agitated to produce a thick, smooth liquid. Most buttermilk sold in the US is not true buttermilk but rather imitation cultured buttermilk.   
Bulgarian buttermilk has yogurt cultures that have replaced the cream cultures. It has increased acidity by fermentation also at higher temperatures; thus it resembles yogurt.

Sour cream

Sour cream is a leaner, firmer version of crème fraîche. It contains 20% milk fat and enough protein to curdle when cooked. It appears to have originated from Central and Eastern Europe and brought to the US in the 19th century.  Since then, Americans have added a small amount of rennet, which contains enzymes that cause protein coagulation. The result is a heavier, firmer sour cream than its European counterpart.
Acidified sour cream is made by coagulating milk with acid instead of through fermentation. It is therefore also known as non-fermented sour cream. Manufacturer versions of low fat and non-fat sour cream replace butterfat with starch, plant gum, and dried milk protein.

Crème fraîche

Crème fraîche is 30% milk fat pasteurized at moderate temperatures. It is not made from UHT (Ultra High Temperature) pasteurized or sterilized milk. Two versions are available: liquid and thick. The liquid crème fraîche is unfermented. It has a shelf life of 15 days. The thick version is fermented with a typical cream culture. It has a shelf life of 30 days.
A home-made version of crème fraîche is made by adding cultured buttermilk or sour cream to heavy cream (1 tbsp per cup) and letting it stand at cool room temperature for 12 to 18 hrs or until thick.

Cream cultures

Cream cultures such as sour cream, crème fraiche, and buttermilk are indigenous to Western and Northern Europe. These products result from the slow fermentation produced by the mesophilic bacteria Lactococci and leuconostoc species. These bacteria have three important characteristics that make them ideal for production of creams and buttermilk: 1. They grow best at moderate temperatures. The process of fermentation can be kept at lower temperatures than those that produce yogurt. 2. They are moderate acid producers. Again, it prevents the formation of yogurt from too acidic a condition. 3. They complement flavor by turning citrate into diacetyl; a compound which gives the fermented milk product a characteristic buttery flavor.

Yogurt

Yogurt originated in the warm climates of Southwest Asia and the Middle East. Though it has been produced for thousands of years, it only gained popularity in Europe in the early 20th century. By the 1920s, yogurt attained factory-scaled production. Broader popularity for yogurt came after the French developed a means to give it a creamy texture and added fruit flavors.

Yogurt production follows the common path of fermented milks: heat and fermentation.  First, the milk is prepared by heating it to concentrate proteins and denature the whey protein lactoglobulin. This treatment improves the consistency of the yogurt. A denatured lactoglobulin allows casein proteins to bond and form a fine matrix that retains liquid in its small interstices instead of coagulating into semi-solid curds.  The milk is then cooled to a warm temperature optimal for bacterial production of lactic acid.
The bacteria used for the fermentation of yogurt are very thermophilic. Industrially, these bacteria include Lactobacillus delbrueckii, subspecies bulgaricus, and Streptococcus salivarius, subspecies thermophilus. These bacteria stimulate each other and in combination acidify milk rapidly. They are also notable for their production of flavor compounds dominated by acetaldehyde, which gives yogurt its fresh, tart flavor.
Fermentation of yogurt at high temperatures of 40 to 45 degrees Celsius (104-113 degrees F) grow bacteria that multiply quickly and produce large amounts of lactic acid. Milk proteins set in 2-3 hrs, but produce a coarse protein network. The proteins assemble in thick strands which give it firmness but leak whey protein readily. In comparison, fermentation of yogurt carried out at 30 degrees Celsius (86 degrees F) grows bacteria more slowly and produces a finer, more intricate network that better retains whey. Yogurt prepared at this lower temperature takes 18 hours to set.
Reduced fat milk yogurt is firmer than the regular kind due to the addition of milk proteins used to mask the lack of fat. The extra milk proteins add density to the coagulated protein network. Manufacturers also add gelatin, starch and other stabilizers.  
Frozen yogurt is somewhat of a misnomer. Commercial frozen yogurt is made from iced milk with small dose of yogurt in it, usually in a ratio of 4:1.

Saturday, March 3, 2012

Health benefits of lactic acid bacteria in fermented milk

Lactic acid bacteria do more than just pre-digest lactose and produce yogurt. Back in the early 1900s, the Russian immunologist Ilya Metchnikov proposed that lactic acid bacteria in fermented milks help eliminate toxic microbes in our digestive system. To support Mr. Metchnikov’s prescient claim, research in recent decades suggests that Bifidobacteria, fostered in breast milk, colonizes the infant intestine and keep it healthy through acidification and production of antibacterial substances. Once the infant is weaned, the Bifidobacteria recede in favor of a mixed population of Streptococcus, Staphylococcus, E. coli, and yeasts.

Bacteria such as L. fermentum, L. casei, L. brevis, and L. acidophilus adhere to the human intestinal wall. Their presence shields it from other microbes by the secretion of antibacterial compounds, and by boosting the immune response to infection. Furthermore, research suggests that these bacteria also dismantle cholesterol and reduce the production of carcinogens.

The consumption of fermented milks for health purposes, however, is debatable. At the time of Mr. Metchnikov’s claim, milk fermentation involved a dozen or more microbes. Industrial versions nowadays usually limit it to two or three. This biological narrowing does not only affect flavor and consistency, but its health value as well. In addition, live cultures in industrial buttermilk and yogurt grow well in milk but cannot survive in the human body. Some manufacturers are adding "probiotic" Lactobacilli and Bifidobacteria to their cultured milk products in an attempt to mimic the original fermented milks. Such products are advertised for the health benefits afore noted.

Lactic acid bacteria and fermented milk

Lactose is almost uniquely found in milk. Few bacteria can break down lactose into usable forms of energy. Lactic acid bacteria, also known as Probiotic bacteria, use the enzyme lactase to break down the disaccharide lactose into the more usable monosaccharides glucose and galactose. The bacteria produce lactic acid as a by-product of lactose digestion. The low pH preserves the milk as other microbes cannot survive in acidic conditions. In addition, casein proteins come together in semi-solid curds. The flavor and texture favorably change in a process referred to as milk fermentation.

The history of milk fermentation dates back at least 2,000 years. In the early years, people believed that the fermentation was a spontaneous process. Later, the process was managed by the inoculation of fresh milk with fermented milk. By the late 19th century, bacteria had been identified as a causative agent, though the process was not entirely understood. By the 1900s, starter cultures of unknown mixed bacteria became commercially available. By the 1930s, pure single-strain cultures had evolved for the specific production of sour creams, yogurts, and cheese.

Fermenting lactic acid bacteria include species in the genera Lactobacillus, Lactococcus, Streptococcus, Leuconostoc, and Pediococcus. Some of these species also colonize the mouth, intestine, and vagina of mammals as normal flora.

Wednesday, February 29, 2012

Griddle cakes

Griddle cakes include pancakes and crumpets. Pancakes are made from viscous and floury batters that retain some gas for the time they cook. The batter is poured onto a griddle and cooked until gas bubbles break the surface of the cake, then flipped to trap remaining gas. Crumpets are small flat, yeast-raised cakes with a pale, cratered surface. They are made from a thicker, bubbly pancake batter that is poured into ring molds. The cake is cooked slowly, unmolded, and turned over.

The fluffy texture of griddle pancakes depend on the development of tiny carbon dioxide gas pockets produced from the reaction of baking soda and an acid such as buttermilk. To obtain the best results, mix ingredients into a batter, then stop mixing before all the clumps of flour dissolve. Over-mixing causes flat, chewy pancakes due to the early escape of carbon dioxide and gluten overdevelopment.  Allow the batter to sit for a while, preferably in the refridgerator. The cold temperature retards gluten development and decreases bacterial growth. With the right amount of gluten protein and CO2 gas, the batter becomes smooth. It spreads easily on the griddle, cooks evenly and thoroughly, and produces light-brown, fluffy pancakes.

Lesson 3: Buttermilk pancakes

This week the focus is on buttermilk pancakes. Topics include:

Griddle pancakes
Fresh fermented milks and creams
Maple and other syrups

Hope you join me!