Publication Date

Spring 2024

Document Type

Thesis

Degree Name

Master of Science

Department

Analytical Chemistry

First Advisor

John R. Sowa

Second Advisor

Joong-Won Shin

Third Advisor

K. G. Sanjaya Ranmohotti

Abstract

Polyol-induced extraction (PIE) is an extraction technique for separating organic solvents from water, using glycerol and polyol as separating agents. Glycerol binds water releasing the organic solvent as a separate liquid phase. this thesis, investigates how the PIE process may be used to separate caffeine and capsaicin. When acetonitrile and water are used as a 1:1 solvent mixture, two immiscible phases are created upon addition of the polyol, glycerol. Initially, for purposes of training on the PIE method, the studies primarly began with the extraction of pure caffeine. Using a 1:1 mixture of acetonitrile and water, 20 m/v % glycerol, the PIE extraction of caffeine was performed at three temperatures (-10, -15, -21 oC). Over this temperature range, the partition coefficient values do not vary within experimental error giving average partition coefficient of 1.01 +/- 0.06.

Next, the extraction and quantification of capsaicin from hot pepper cultivars began. Capsaicinoids are the group of compounds that gives hot peppers and sauces their spicy taste and is expressed as Scoville Heat Units (SHU). The two major chemicals in the peppers that cause the hot sensation are capsaicin (1) and dihydrocapsaicin (2). The partition coefficient of a pure sample of natural capsaicin studied at -21 oC and gave a value of 130 +/- 60 indicating that they are quantitatively transferred to the upper acetonitrile layer. The percent recovery of a pure sample of natural capsaicin was only 44 percent. The PIE extraction was then performed on five varieties of dried and ground commercially purchased, dried, hot peppers. The extraction procedure was optimized with ground cayenne pepper which under optimal conditions had an SHU value of 29,624 +/- 1,192. Ghost pepper had a SHU of 289,193. Dried chili pepper had a Scoville of 68,713 SHU. Ancho chili had a Scoville heat unit of 822 SHU This thesis, concludes that the PIE process is an effective method for the analytical determination of capsaicinoids in dried hot peppers.

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