Maraschino Cherry: A Laboratory‐Lecture Unit

Abstract

Oregon State Univ. has offered FST 102 “Maraschino Cherry” as a 1‐credit orientation course since 1994. The maraschino cherry serves as a vehicle from which faculty give their disciplinary perspective, for example, the chemistry of the maraschino cherry, processing unit operations, microbiology and food safety, food law, sensory analysis, product development, and so on. This laboratory‐lecture unit was developed to provide reference background information, including instructions for making maraschino cherries. The unit explains the functions of SO2, CaCl2, acidulants (citric or HCl), and sodium chlorite in cherry brine formulations, as well as the critical role of pH in cherry brine formulation and processing of maraschino cherries. How to estimate °Brix of sugar syrups by the Pearson square method is described. The unit gives students an understanding of the regulatory distinctions between certified colorants and colorants exempt from certification; artificial, natural, and with other natural flavors (WONF) flavorings; and additives and ingredients. A brief historical perspective of maraschino cherries is given. Study questions and suggested student projects are included.

At-Home Laboratory Experiments for the Analytical Chemistry Curriculum

“…The concentration of Allura Red in maraschino cherry juice was determined by the students to be ∼140 and ∼130 ppm by external and standard additions calibration, respectively (Table ). These values were consistent with those obtained by the instructors and fell within the expected concentration range of 100–150 ppm, increasing confidence in the students' values. Further, the maximum allowed concentration of Allura Red in foods and beverages is between 100 and 300 ppm, so the experimental method described here can be easily adapted to other products (e.g., sports drinks, mouthwash, etc.…”

A Simple and Inexpensive Invisible Ink System Based on Red Cabbage Extracts

“…Vinegar is readily available in grocery stores, citric acid is a component of some household cleaning products, and potassium aluminum sulfate “alum” is commercially available for domestic use (for example, it is often used as a mordant in home dyeing of fibers). Red cabbage extract is not unique in having the ability to react with bisulfite ions in solution, and many other anthocyanin sources exhibit very similar behavior . In the Supporting Information (pp S6 and S7), we identify additional sources of anthocyanins that can also be used to make anthocyanin-derived invisible inks.…”

“…Recent literature reports provide some useful suggestions, and it is known that Al 3+ complexes of anthocyanins can afford blue/ purple solutions. 8,12,18 However, a precise description of the process that takes place in the presence of potassium alum is harder to elucidate. Perhaps the most well-known example of an anthocyanin complex with aluminum ions is the delphinidin/Al 3+ complex 16 (structure 1, Figure 4) that is responsible for the color of blue hydrangea sepals.…”

“…As part of our summer school program, we desired a simple, but engaging, demonstration of an aspect of anthocyanin chemistry that was relevant to the food and drink industry. In previous work, we have explored bleaching reactions of anthocyanins with solutions of sodium metabisulfite. , This type of bleaching process is well studied within the food industry; this is because sulfites are used as preservatives for fruit products, and in certain drinks. − The underlying chemistry also links to observations that may be familiar to students in everyday life. Useful examples of anthocyanin bleaching processes that involve sulfites include control of undesirable “pinking” of white wines, and production of maraschino cherries .…”

“…In previous work, we have explored bleaching reactions of anthocyanins with solutions of sodium metabisulfite. , This type of bleaching process is well studied within the food industry; this is because sulfites are used as preservatives for fruit products, and in certain drinks. − The underlying chemistry also links to observations that may be familiar to students in everyday life. Useful examples of anthocyanin bleaching processes that involve sulfites include control of undesirable “pinking” of white wines, and production of maraschino cherries . A key step in the latter process requires decolorization of the fruit anthocyanins prior to addition of red food coloring.…”