Week 2: I enter the classroom with bubbling-over enthusiasm for the topic and just a hint of trepidation concerning the fact that I, a through and through art history major, am now enrolled in CHEM 360. As expected, some of the lecture consisted of molecular diagrams that gave me heart palpitations. But Professor Didem thoroughly explained the chain of concepts from carbons to cutting board and it became fascinating to discover the chemical explanations behind culinary concepts I have a practical understanding of as an avid chef.
For our first test, we made pea butter from two different pea sources; frozen peas and canned peas. The former a livid kelly green, the latter a yellowish olive green. Both samples were blended and then centrifuged. The results revealed two distinct layers in the canned pea tubes and three distinct layers in the frozen pea tubes. The bottom of both samples was the higher density pea solids; cell walls and starches. The top layer was a purified pea broth. I quickly learned in the classroom to refrain from calling it pea water. The middle layer of the frozen peas was this vibrant green, glistening substance. It had a concentrated, nutty-sweet flavor. We had made pea butter!
Later we tasted our way through the rainbow of vegetable and fruit pigments. It was insightful to discover the properties of certain pigments in produce and how it relates to the molecular-level structures. The carotenoids in the crispy yellow pepper I munched on are accessory pigments in photosynthesis and pass solar energy to chlorophyll.
Week 3 included more centrifugal fun! We jumped right into de-pitting three varieties of olives (purple, black, and green) and blending each into a smooth paste. The mixtures were sent to the centrifuge for 40 minutes.
During this wait time my classmates and I became oil sommeliers and analyzed the viscosity, taste, and appearance of six different oils. I quickly discovered that I am an oil snob. Only the extra virgin olive oil was satisfactory. The rich grip of the initial earthiness and peppery after-bite was very distinct. All I needed was a slice of ciabatta…
When we checked on our high-speed revolving olive mixtures I was delighted to discover a layer of olive solids and liquid gold floating above the pellets. Yes, we had made our own olive oil. I hesitate to term our product “extra virgin” because I learned that such distinctions are conditional not on the chronology of the press but the percentage of free fatty acids. Olive oil’s “acidity” is a result of the degree of breakdown of the triacylglycerols, due to a chemical reaction called hydrolysis or lipolysis, in which free fatty acids are formed. Oil extracted carelessly and/or from poor quality fruit is plagued with higher quantities of these broken down triacylglycerols. High quality oil; meticulously made from healthy, freshly picked olives, normally has a pretty low “acidity”, well under 0.5% FFA. Extra virgin olive oils have less than 0.8% FFA.
It is only Week 3 and I am already enjoying this experience that blends one of my dearest passions with the stimulation of intellectual growth. I look forward to more tasteful discovery!
Jocelyn