Lemon Squares Recipe
1 cup butter, softened
½ cup white sugar
2 cups all-purpose flour
1 ½ cup white sugar
¼ cup all –purpose flour
2/3 cup lemon juice
2 tbs. lemon zest
- Preheat oven to 350°
- Cream together the butter, 2 c. flour, and ½ c sugar. Press into the bottom of a 9x13in pan, ungreased. Bake for 15-20min.
- Combine the remaining sugar and flour by whisking. Add in eggs, lemon juice, and zest. Pour filling over the crust after baking.
- Bake again for 20 min. Allow bars to cool before serving so they have time to firm up.
- Dust with powdered sugar once cool. Cut bars into squares. Enjoy.
Lemon Squares: A Study of Vitamin C
A major component of this lemon squares recipes is lemons. Today lemons are commonly used across various cultures in cooking, in dishes from lemon-garlic chicken to Peruvian ceviche. However, fresh fruits and vegetables have not always been so widely available as they are today, making this recipe a relatively recent innovation over the span of culinary history. A lack of these fresh foods presented itself in a debilitating condition known as scurvy, which plagued many sailors in the 15th century1. Those inflicted with scurvy experienced loose teeth, bleeding or swollen gums, slow healing wounds, and skin that easily bruised. Scurvy was also the main cause of death at sea since during this time, it was unknown but these sailors were experiencing a deficiency of vitamin C1. Various researchers attempted to pinpoint the underlying mechanism and cause of these symptoms but it wasn’t until Albert Szent-Györgyi’s discovery of absorbic acid, commonly known as vitamin C, that resulted in a fundamental step in our current understanding of modern nutrition.
Although researchers before Szent-Györgyi had presumed about the existence of vitamin C, there was no solid evidence that proved this concept. After receiving his medical degree at the University of Budapest, Szent-Györgyi first isolated a molecule with six carbons in his studies regarding the molecular level of food metabolism. The molecule he discovered uniquely displayed properties of both a sugar and an acid, which he coined a “hexuronic acid”. Szent-Györgyi was able to isolate this exact substance during the 1920s through his work on the browning of citrus plants. Szent-Györgyi took his discoveries back to Hungary in order to collaborate with a researcher who was well versed in vitamin research, J.L. Svirbely1.
Together, Szent-Györgyi and Svirbely explored vitamin C deficiency in guinea pigs by limiting one group to only the consumption of boiled food (whose vitamin C was destroyed in the heating process) while the other group was fed foods rich in hexuronic acid. The first group showed symptoms of how scurvy presented itself in humans and these guinea pigs died eventually whereas the second group thrived. Due to its anti-scurvy abilities, Szent-Györgyi renamed hexuronic acid to “ascorbic acid” to reflect its properties. In 1933, Szent-Györgyi successfully purified 3 pounds of ascorbic acid from paprika in order to prove that ascorbic acid was truly vitamin C. He later received the Novel Prize for his work identifying ascorbic acid in 1937, surprisingly enough he was the only scientist recognized in this award out of the many who were involved in the discovery and isolation of vitamin C1.
With this groundbreaking research, Szent-Györgyi paved the way for future nutritional science studies to discover the functional significance of vitamin C within the human body. Today it is well understood that vitamin C is essential in the formation of collagen, various neurotransmitters, and L-carnitine. Collagen is an essential protein that is structurally involved in connective tissues in humans as well as in wound repair. Additionally, vitamin C is believed to be a necessary antioxidant, which protects cells from harmful free radicals that could ensue damage. Therefore, vitamin C is essential in the growth and maintenance of ligaments, gums, bones, internal organs, blood vessels, and teeth2.
Since it’s discovery in 1933, vitamin C is now identified in a wide variety of foods. Many are aware that citrus fruits, such as grapefruits, lemons, limes, and oranges, are rich in vitamin C. However, vitamin C is also found in many vegetables, including cabbages, spinach, potatoes, and broccoli2. It is important to note that the processing of some of these food items through cooking, drying, salting, or even exposure to air may affect the nutritional content that is delivered1. Vitamin C is characterized as a water-soluble nutrient, so there tends to be a large difference in nutritional content of cooked vs. uncooked vegetables. For example, cooked spinach only contains 1/3 of the vitamin C found in raw spinach. However, it has been found that frozen produce tends to have higher vitamin C levels compared to fresh fruit since during storage and transportation, nutrients are lost2.
Today, while scurvy is much more rare, vitamin C deficiency is still present, especially among those who are generally malnourished. In general, vitamin C deficiency is cause by an inadequate diet, particularly, one lacking in fresh fruits and vegetables, not necessarily just a lack of food. The major result of vitamin C deficiency is an overall weakening of the capillaries, which results in hemorrhages and bones (or related structures) having various defects. Long-term depletion of nutrients (after weeks or months) will result in weakness, lack of energy, weight loss, irritability, muscle pain, and joint pain. In order to prevent vitamin C deficiency or scurvy, adults are recommended to consume 5 servings of fruits and vegetables each day with the intention to consume at least 200mg of vitamin C3.
- Albert Szent-Gyorgyi Vitamin C – Landmark. (n.d.). Retrieved from https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/szentgyorgyi.html
- Office of Dietary Supplements – Vitamin C. (n.d.). Retrieved from https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
- Parker-Pope, T. (2013, October 18). Ask Well: Does Boiling or Baking Vegetables Destroy Their Vitamins? Retrieved from https://well.blogs.nytimes.com/2013/10/18/ask-well-does-boiling-or-baking-vegetables-destroy-their-vitamins/