GOOD EATS: BLUEBERRIES
Editor's Note: In this exploration,Jing Jing K. ('19) explores the chemistry and recipes with blueberries.
Ever wondered how you could turn blueberries into an all-year around treat? Well you are in luck! In episode 15 of the Food Network series, Good Eats, Alton Brown, creator of the show, talks about specialty recipes in which you can incorporate blueberries. The key to having these amazing fruits available year round is buying fresh local produce and using certain freezing techniques. Brown uses the frozen berries to bake an old fashioned buckle cake, a pie, and make fresh blueberry juice. The secret to a perfect pie? Choosing the correct kind of starch.
Some interesting history on blueberries: Elizabeth White, an agricultural specialist, sparked the revolution of the commercial blueberry business. She contacted USDA scientist, Frederick Coville, who was studying how to propagate this crop, to supply him with pickers to find the best blueberries in the wild. As a result of White’s work, the highbush blueberry was developed. This bush contained big berries that were easy to harvest and is where we get our main supply of them today (Brown, 2006).
In the episode, Alton Brown pretends to travel through time to the winter season. During winter, blueberries are scarce in North America because it is off season, so most of them are imported from Chile. Blueberries are a relatively new crop outside the U.S., and because of this, imported blueberries are much more expensive than local varieties bought in season. Having them picked, packed, and shipped thousands of miles often means that they are not fresh and are tasteless blue bombs. You are much better off buying fresh, local berries. When you search for blueberries you want them to be dry, wrinkle free, firm, and a nice indigo blue. Also, they should have a silver frost on them, which is also called fruit bloom; this is the process of waterproofing where the blueberries create a film to protect themselves from the sun (Brown, 2006).
Due to the blueberry’s size, texture, shape, and sugar content, they are an excellent fruit to freeze--which allows you to enjoy them in any season. Freezing these little magical fruits will leave their natural sweetness and deep blue color. In the freezer, blueberries can last up to a year if stored correctly. Alton Brown suggests that you freeze them immediately without washing them, so they do not become moldy. Freezing them immediately will lead to smaller ice crystals forming in them, creating less damage as they freeze. That means less weeping when they are thawed. Take a metal baking sheet and spread the blueberries evenly. Metal is an excellent conductor that allows them to freeze quickly. Once they have hardened, you can put them in a storage bag in the bottom compartment of your freezer (Brown, 2006).
In recent studies, some scientists have found that after freezing blueberries have increased levels of anthocyanin, the pigment that makes their hue blue. Frozen blueberries have been found to have a higher concentration of delphinidin glycosides than fresh ones. Delphinidin glycosides are one of many components that make up 75% of anthocyanins. Researchers have also found out that using the post-harvest technique, IQF (Individual Quick Frozen), results in an increase in polyphenolic compounds, which are found typically on the outside layer of the skin. It was also indicated that after regeneration the outer layer of IQF blueberries could accelerate the rate of dying (Michalska and Lysiak, 2015).
One of the classic recipes to use blueberries in is a good old fashion pie. Brown wants to freeze his pie filling, so he decides to use a starch called amylopectin-packed tapioca flour. Blueberries contain pectin, which is a natural thickener, but not enough to make a good pie filling. Brown says a perfect pie also needs flour or starch. Starches are great for cooking, but especially for pie fillings because they are thickening agents that gelatinize, which maintains the retention of gas and prevents the pie from caving in on itself during baking and cooling. How starch performs depends on how much of the two forms of starch, amylose and amylopectin, they contain. A starch that is high in amylose creates a strong gel across a small temperature range. Amylose on a molecular level is coiled to have enough room for an iodine molecule, which gives it the characteristic of turning a blue-violet color (Tharanathan, 2005). However, a starch that is high in amylopectin will still create a gel, but not as thick as a starch that contains amylose. Amylopectin can also tolerate temperatures well below freezing, which justifies Brown’s decision to use in his pie (Brown, 2006). Amylopectin under an electron microscope would look like a branched-chain with thousands of glucose units. Instead of the blue-violet color amylose changes when mixed with iodine, it produces a reddish brown color due to the disruption of the helical construction (Chinachoti, 1995). This process will lead to a spectacular pie if you choose the correct kind of starch.
Now that you know the proper way to freeze blueberries - quickly and individually - you can enjoy this delicious delight anytime of the year. If you are making a pie, with the right kind of starch cooked at the right temperature, you can produce a thick and perfectly gelled filling. Say goodbye to watery pie filling and wrinkled, tasteless fruits!
Some interesting history on blueberries: Elizabeth White, an agricultural specialist, sparked the revolution of the commercial blueberry business. She contacted USDA scientist, Frederick Coville, who was studying how to propagate this crop, to supply him with pickers to find the best blueberries in the wild. As a result of White’s work, the highbush blueberry was developed. This bush contained big berries that were easy to harvest and is where we get our main supply of them today (Brown, 2006).
In the episode, Alton Brown pretends to travel through time to the winter season. During winter, blueberries are scarce in North America because it is off season, so most of them are imported from Chile. Blueberries are a relatively new crop outside the U.S., and because of this, imported blueberries are much more expensive than local varieties bought in season. Having them picked, packed, and shipped thousands of miles often means that they are not fresh and are tasteless blue bombs. You are much better off buying fresh, local berries. When you search for blueberries you want them to be dry, wrinkle free, firm, and a nice indigo blue. Also, they should have a silver frost on them, which is also called fruit bloom; this is the process of waterproofing where the blueberries create a film to protect themselves from the sun (Brown, 2006).
Due to the blueberry’s size, texture, shape, and sugar content, they are an excellent fruit to freeze--which allows you to enjoy them in any season. Freezing these little magical fruits will leave their natural sweetness and deep blue color. In the freezer, blueberries can last up to a year if stored correctly. Alton Brown suggests that you freeze them immediately without washing them, so they do not become moldy. Freezing them immediately will lead to smaller ice crystals forming in them, creating less damage as they freeze. That means less weeping when they are thawed. Take a metal baking sheet and spread the blueberries evenly. Metal is an excellent conductor that allows them to freeze quickly. Once they have hardened, you can put them in a storage bag in the bottom compartment of your freezer (Brown, 2006).
In recent studies, some scientists have found that after freezing blueberries have increased levels of anthocyanin, the pigment that makes their hue blue. Frozen blueberries have been found to have a higher concentration of delphinidin glycosides than fresh ones. Delphinidin glycosides are one of many components that make up 75% of anthocyanins. Researchers have also found out that using the post-harvest technique, IQF (Individual Quick Frozen), results in an increase in polyphenolic compounds, which are found typically on the outside layer of the skin. It was also indicated that after regeneration the outer layer of IQF blueberries could accelerate the rate of dying (Michalska and Lysiak, 2015).
One of the classic recipes to use blueberries in is a good old fashion pie. Brown wants to freeze his pie filling, so he decides to use a starch called amylopectin-packed tapioca flour. Blueberries contain pectin, which is a natural thickener, but not enough to make a good pie filling. Brown says a perfect pie also needs flour or starch. Starches are great for cooking, but especially for pie fillings because they are thickening agents that gelatinize, which maintains the retention of gas and prevents the pie from caving in on itself during baking and cooling. How starch performs depends on how much of the two forms of starch, amylose and amylopectin, they contain. A starch that is high in amylose creates a strong gel across a small temperature range. Amylose on a molecular level is coiled to have enough room for an iodine molecule, which gives it the characteristic of turning a blue-violet color (Tharanathan, 2005). However, a starch that is high in amylopectin will still create a gel, but not as thick as a starch that contains amylose. Amylopectin can also tolerate temperatures well below freezing, which justifies Brown’s decision to use in his pie (Brown, 2006). Amylopectin under an electron microscope would look like a branched-chain with thousands of glucose units. Instead of the blue-violet color amylose changes when mixed with iodine, it produces a reddish brown color due to the disruption of the helical construction (Chinachoti, 1995). This process will lead to a spectacular pie if you choose the correct kind of starch.
Now that you know the proper way to freeze blueberries - quickly and individually - you can enjoy this delicious delight anytime of the year. If you are making a pie, with the right kind of starch cooked at the right temperature, you can produce a thick and perfectly gelled filling. Say goodbye to watery pie filling and wrinkled, tasteless fruits!
