Graduate Thesis Or Dissertation

 

Changes in raspberry pigments during processing and storage Public Deposited

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/js956m439

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  • The retention of pigments in processed raspberries is a function of the process method and conditions of subsequent storage. The presence of sucrose and the nature of the headspace gas also influences the retention of the pigment. The effect of some of the above variables on the pigments was investigated. Variables imposed were: (1) concentration of syrup, (2) headspace gas atmosphere, (3) temperature, and (4) time of storage. Separation of the pigment of Willamette red raspberries and black raspberries was made by column chromatography and the pigments were analyzed. spectrophotometrically. The results showed the following: 1. The pigments of Willamette red raspberries consisted of four separate cyanins as based on the R [subscript f] values and characteristic wavelengths of maximum absorption. The pigments of black raspberries consisted of three fractions. 2. On the basis of R [subscript f] values and wavelengths of maximum absorption only two of the constituent fractions were the same. 3. The wavelength of maximum absorption of all the anthocyanins shifted towards shorter wavelengths after the first month of storage. 4. Time and temperature of storage and their interaction each contributed significantly to the destruction of the cyanin pigments. An increase in either variable resulted in a greater destruction of the pigments. 5. As the concentration of the ingoing syrup was increased, the amount of individual cyanins decreased. 6. Oxygen in the headspace gas was shown to be detrimental to the retention of the cyanins I, II, and IV of the Willamette raspberries and to cyanins II and III of the black raspberries. 7. Changes in the total pigment concentration were greatly influenced by the cyanin in greatest concentration in the species. 8. Heat processing destroyed approximately 20 percent of the pigments of the raspberries.
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