Assignment 04 Catechin Content in Pulses
Jason Thon
Nicole Odom
Assignment 04 – Catechin Content in Pulses
The differences in phenolic content of both regular and nondarkeningcranberry beans, in raw and cooked form, were studied. After high pressure steaming, catechin, a common antioxidant often found in pulses,exhibited a content increase, likely due to larger compounds containing the antioxidant breaking down. Further, the researchers found an unusually small difference in phenolic content in the Red Rider cranberry beans after cooking, while flavonoid and proanthocyanidincomposition dropped significantly. This can likely be attributed to their technique of retaining water used to cook the beans, as it was found the water itself contains 26-52% of total phenolic content in similar experiments with different beans.[1]
Catechin acts as an antioxidant by being easily oxidized itself. The oxidation method in which catechinformsquinone is rather straight forward. As seen in Scheme 1, the catechin molecule begins with two alcohol groups off of the same benzene ring. A single proton, followed by a single electron, is removed, leaving an alcohol group and an oxygen radical. This repeats, insteadwith the removal of the hydrogen from the second alcohol, leaving a second radical. Electrons in the resulting structure move around the ring to form double bonds with both oxygens, restoring the electronic stability of the molecule.
The ultraviolet/visible spectra of catechin in water at various pH levels can been seen in Figure 1. The spectra of catechin in the absence of oxidizing agents, as depicted by the dashed line, shows a λmaxat 275 nm. It can also be noted that there is no absorbance at 435 nm, even after extended time periods, concluding that there is no significant change. However, when using aerated solutions, there is a change within 24 hours.[2] This change presents as a shift towards the long wavelengths, appearing at 430 nm and 480 nm, showing that catechin can more readily change structure through oxidation, resulting in the quinone form. Further, it can also be seen that catechin is more prone to oxidation in alkaline solutions. Deviations in pH towards alkalinity result in higher absorbance at each aerated λmax.
Differential Scanning Calorimetry of both Red Rider and nondarkening cranberry beans were performed, producing a combined thermogram that displays two endothermic patterns (Figure 2). Both graphs show endothermic events around 70-85ᵒC, attributed to starch gelitanization, which occurs when the intermolecular bonds in starch break down to the point that hydrogen bonding with water occurs much more readily.[3] There is another endothermic event around 90-105ᵒC, representing the melting of the amylose-lipid complexes, which comprise the basic structure of pulses. As seen in Figure 2, the Red Rider variety of cranberry beans shows a decreased enthalpy of melting by their decreased fatty acid content
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Jason Thon
Nicole Odom
Scheme 1: Quinone Synthesis from Catechin
Figure 1. Absorption of 0.2 mM solution of catechin in water at various pH. For pH = 7dearated(λmax,m [nm], σm [nm], hm, nm): 271, 17, 0.32, 0.3206 (m = 1); 271, 4, 0.1, 0.1032 (m = 2); 279, 2, 0.04, 0.0453 (m = 3); 312, 30, 0.029, 0.0291 (m = 4). For pH = 7: 215, 21, 0.41, 0.0047 (m = 1); 268, 20, 0.3, 0.2992 (m = 2); 276, 8, 0.26, 0.2589 (m = 3); 288, 4, 0.08, 0.0867 (m = 4); 296, 5, 0.009, 0.0871 (m = 5); 310, 20, 0.1, 0.2184 (m = 6); 420, 40, 0.0009, 0.2677 (m = 7); 442, 17, 3.90E-20, 0.1276 (m = 8); 505, 40, 3.90E-8, 0.1444 (m = 9). For pH = 8: 240, 15, 1.39, 1.57 (m = 1); 292, 21, 0.85, 0.8497 (m = 2); 328, 13, 0.3, 0.2998 (m = 3); 398, 40, 1, 0.9999 (m = 4); 432, 6, 0.02, 0.0191 (m = 5); 443, 6, 0.02, 0.0189 (m = 6); 510, 40, 0.2, 0.2 (m = 7). For pH = 9: 240, 15, 1.6, 1.4 (m = 1); 293, 22, 0.98, 0.9789 (m = 2); 327, 10, 0.16, 0.1587 (m = 3); 400, 47, 1.3, 1.3 (m = 4); 425, 2, 0.007, 0.007 (m = 5); 430, 2, 0.008, 0.008 (m = 6); 520, 38, 0.25, 0.25 (m = 7). For pH = 10: 205, 34, 2.1, 1.3451 (m = 1); 298, 20, 1.05, 1.0454 (m = 2); 325, 9, 0.22, 0.22 (m = 3); 340, 10, 0.15, 0.15 (m = 4); 400, 45, 1.5, 1.5 (m = 5); 430, 5, 0.009, 0.009 (m = 6); 520, 38, 0.3, 0.3 (m = 7).For pH = 12:205, 34, 2.2, 0.0049 (m = 1); 298, 19, 1.23, 0.0209 (m = 2); 326, 9, .3, 0.0441 (m = 3); 340, 10, .15, 0.0399 (m = 4); 400, 45, 1.7, 0.0089 (m = 5); 430, 5, .009, 0.0798 (m = 6); 520, 38, .3, 0.0105 (m = 7).
Figure 2. Thermograms of raw red rider and nondarkeningcranberry beans. For N = RRR (s, c [mW]; λmax,m [nm], σm [nm], hm, nm): -0.0292, -21.5; 77.5, 5, -0.8, -0.8 (m = 1); 93, 3.5, -0.6, -0.6 (m = 2). For N = CNDR: -0.0292, -22.45; 79, 5, -0.8, -0.8 (m = 1); 98, 2.5, -1, -1 (m = 2).
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([1]) Chen, P. X.; Dupuis, J, H.; Marcone, M., F.; Pauls, P., K.; Liu, R.; Liu, Q.; Tang, Y.; Zhang, B.; and Tsao, R.; Physicochemical Properties and in Vitro Digestibility of Cooked Regular and Nondarkening Cranberry Beans (Phaseolus vulgaris L.) and Their Effects on Bioaccessibility, Phenolic Composition, and Antioxidant Activity. J. Agric. Food Chem.2015, 63, 10448-10458.
([2]) Sarkar, D.; Das, S.; Pramanik, A. A Solution Spectroscopy Study of Tea Polyphenol and Cellulose: Effect of Surfactants. RSC Adv.2014, 4, 36196.
([3]) Hegenbart, S. Understanding Starch Functionality. Understanding Starch Functionality, (accessed Mar 1, 2016).