79 research outputs found
Changes in cocoa properties induced by the alkalization process: A review
[EN] Alkalization, also known as "Dutching," is an optional, but very useful, step taken in the production chain of cocoa to darken its color, modify its taste, and increase natural cocoa solubility. Over the years, various attempts have been made to design new and more effective alkalization methods. Moreover, different authors have attempted to elucidate the impact of alkalization on the physicochemical, nutritional, functional, microbiological, and sensory characteristics of alkalized cocoa. The aim of this review is to provide a clear guide about not only the conditions that can be applied to alkalize cocoa, but also the reported effects of alkalization on the nutritional, functional, microbiological, and sensory characteristics of cocoa. The first part of this review describes different cocoa alkalization systems and how they can be tuned to induce specific changes in cocoa properties. The second part is a holistic analysis of the effects of the alkalization process on different cocoa features, performed by emphasizing the biochemistry behind all these transformations.European Regional Development Fund, Grant/Award Number: Project RTC-2016-5241-2; Ministerio deEconomia y Competitividad, Grant/Award Number: Project RTC-2016-5241-2Valverde-Garcia, D.; PĂ©rez-Esteve, Ă.; Barat Baviera, JM. (2020). Changes in cocoa properties induced by the alkalization process: A review. Comprehensive Reviews in Food Science and Food Safety. 19(4):2200-2221. https://doi.org/10.1111/1541-4337.12581S22002221194Ilesanmi Adeyeye, E. (2016). Proximate, Mineral And Antinutrient Compositions Of Natural Cocoa Cake, Cocoa Liquor And Alkalized Cocoa Powders. Journal of Advanced Pharmaceutical Science And Technology, 1(3), 12-28. doi:10.14302/issn.2328-0182.japst-15-855Ajandouz, E. H., Tchiakpe, L. S., Ore, F. D., Benajiba, A., & Puigserver, A. (2001). Effects of pH on Caramelization and Maillard Reaction Kinetics in Fructose-Lysine Model Systems. Journal of Food Science, 66(7), 926-931. doi:10.1111/j.1365-2621.2001.tb08213.xAndres-Lacueva, C., Monagas, M., Khan, N., Izquierdo-Pulido, M., Urpi-Sarda, M., Permanyer, J., & Lamuela-RaventĂłs, R. M. (2008). Flavanol and Flavonol Contents of Cocoa Powder Products: Influence of the Manufacturing Process. Journal of Agricultural and Food Chemistry, 56(9), 3111-3117. doi:10.1021/jf0728754Andruszkiewicz, P. J., DâSouza, R. N., Altun, I., Corno, M., & Kuhnert, N. (2019). Thermally-induced formation of taste-active 2,5-diketopiperazines from short-chain peptide precursors in cocoa. Food Research International, 121, 217-228. doi:10.1016/j.foodres.2019.03.015Aprotosoaie, A. C., Luca, S. V., & Miron, A. (2015). Flavor Chemistry of Cocoa and Cocoa Products-An Overview. Comprehensive Reviews in Food Science and Food Safety, 15(1), 73-91. doi:10.1111/1541-4337.12180Aremu, C. Y., Agiang, M. A., & Ayatse, J. O. I. (1995). Nutrient and antinutrient profiles of raw and fermented cocoa beans. Plant Foods for Human Nutrition, 48(3), 217-223. doi:10.1007/bf01088443Bandi J. P. Kubicek K. &Raboud P. B.(1984).Installation for solubilizing cocoa. US4438681A.Baigrie, B. D. (1994). Cocoa flavour. Understanding Natural Flavors, 268-282. doi:10.1007/978-1-4615-2143-3_17Bartella, L., Di Donna, L., Napoli, A., Siciliano, C., Sindona, G., & Mazzotti, F. (2019). A rapid method for the assay of methylxanthines alkaloids: Theobromine, theophylline and caffeine, in cocoa products and drugs by paper spray tandem mass spectrometry. Food Chemistry, 278, 261-266. doi:10.1016/j.foodchem.2018.11.072Bauermeister J.(1989).Process for making cacao powder by disagglomeration and cacao powder granulate by subsequent agglomeration. EP0310790A2.Beg, M. S., Ahmad, S., Jan, K., & Bashir, K. (2017). Status, supply chain and processing of cocoa - A review. Trends in Food Science & Technology, 66, 108-116. doi:10.1016/j.tifs.2017.06.007Biehl B.(1986).Cocoa fermentation and problem of acidity overâfermentation and low cocoa flavour.Selangor Malaysia: Incorporated Society of Planters.Serra BonvehĂ, J., & Ventura Coll, F. (2000). Evaluation of purine alkaloids and diketopiperazines contents in processed cocoa powder. European Food Research and Technology, 210(3), 189-195. doi:10.1007/pl00005510Borthwick, A. D., & Da Costa, N. C. (2015). 2,5-diketopiperazines in food and beverages: Taste and bioactivity. Critical Reviews in Food Science and Nutrition, 57(4), 718-742. doi:10.1080/10408398.2014.911142Chalin M. L.(1972).Method of dutching cocoa. US3868469A.Rainer Cremer, D. (2000). The reaction kinetics for the formation of Strecker aldehydes in low moisture model systems and in plant powders. Food Chemistry, 71(1), 37-43. doi:10.1016/s0308-8146(00)00122-9De Vuyst, L., & Weckx, S. (2016). The cocoa bean fermentation process: from ecosystem analysis to starter culture development. Journal of Applied Microbiology, 121(1), 5-17. doi:10.1111/jam.13045Del Rio, D., Costa, L. G., Lean, M. E. J., & Crozier, A. (2010). Polyphenols and health: What compounds are involved? Nutrition, Metabolism and Cardiovascular Diseases, 20(1), 1-6. doi:10.1016/j.numecd.2009.05.015DomĂnguez-RodrĂguez, G., Marina, M. L., & Plaza, M. (2017). Strategies for the extraction and analysis of non-extractable polyphenols from plants. Journal of Chromatography A, 1514, 1-15. doi:10.1016/j.chroma.2017.07.066El Gharras, H. (2009). Polyphenols: food sources, properties and applications - a review. International Journal of Food Science & Technology, 44(12), 2512-2518. doi:10.1111/j.1365-2621.2009.02077.xEllis L. D.(1990).Process for making dark cocoa. US5114730A.Ellis L. D. (1992).Process for making dark cocoa. US5114730A.Lu, F., Rodriguez-Garcia, J., Van Damme, I., Westwood, N. J., Shaw, L., Robinson, J. S., ⊠Charalampopoulos, D. (2018). Valorisation strategies for cocoa pod husk and its fractions. Current Opinion in Green and Sustainable Chemistry, 14, 80-88. doi:10.1016/j.cogsc.2018.07.007Franco, R., Oñatibia-Astibia, A., & MartĂnez-Pinilla, E. (2013). Health Benefits of Methylxanthines in Cacao and Chocolate. Nutrients, 5(10), 4159-4173. doi:10.3390/nu5104159Germann, D., Stark, T. D., & Hofmann, T. (2019). Formation and Characterization of Polyphenol-Derived Red Chromophores. Enhancing the Color of Processed Cocoa Powders: Part 1. Journal of Agricultural and Food Chemistry, 67(16), 4632-4642. doi:10.1021/acs.jafc.9b01049Germann, D., Stark, T. D., & Hofmann, T. (2019). Formation and Characterization of Polyphenol-Derived Red Chromophores. Enhancing the Color of Processed Cocoa Powders: Part 2. Journal of Agricultural and Food Chemistry, 67(16), 4643-4651. doi:10.1021/acs.jafc.9b01050Gobert, J., & Glomb, M. A. (2009). Degradation of Glucose: Reinvestigation of Reactive α-Dicarbonyl Compoundsâ . Journal of Agricultural and Food Chemistry, 57(18), 8591-8597. doi:10.1021/jf9019085Gu, L., House, S. E., Wu, X., Ou, B., & Prior, R. L. (2006). Procyanidin and Catechin Contents and Antioxidant Capacity of Cocoa and Chocolate Products. Journal of Agricultural and Food Chemistry, 54(11), 4057-4061. doi:10.1021/jf060360rGĂŒltekin-ĂzgĂŒven, M., BerktaĆ, I., & Ăzçelik, B. (2016). Change in stability of procyanidins, antioxidant capacity and in-vitro bioaccessibility during processing of cocoa powder from cocoa beans. LWT - Food Science and Technology, 72, 559-565. doi:10.1016/j.lwt.2016.04.065Hagerman, A. E. (1992). TanninâProtein Interactions. Phenolic Compounds in Food and Their Effects on Health I, 236-247. doi:10.1021/bk-1992-0506.ch019Holkar, C. R., Jadhav, A. J., & Pinjari, D. V. (2019). A critical review on the possible remediation of sediment in cocoa/coffee flavored milk. Trends in Food Science & Technology, 86, 199-208. doi:10.1016/j.tifs.2019.02.035Huang, Y., & Barringer, S. A. (2010). Alkylpyrazines and Other Volatiles in Cocoa Liquors at pH 5 to 8, by Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS). Journal of Food Science, 75(1), C121-C127. doi:10.1111/j.1750-3841.2009.01455.xHurst, W. J., Krake, S. H., Bergmeier, S. C., Payne, M. J., Miller, K. B., & Stuart, D. A. (2011). Impact of fermentation, drying, roasting and Dutch processing on flavan-3-ol stereochemistry in cacao beans and cocoa ingredients. Chemistry Central Journal, 5(1). doi:10.1186/1752-153x-5-53International Cocoa Organization(2017).Annual report 2014/2015 Retrieved fromhttps://www.icco.org/about-us/international-cocoa-agreements/cat_view/1-annual-report.html.Mazor JoliÄ, S., RadojÄiÄ RedovnikoviÄ, I., MarkoviÄ, K., Ivanec Ć ipuĆĄiÄ, Ä., & Delonga, K. (2011). Changes of phenolic compounds and antioxidant capacity in cocoa beans processing. International Journal of Food Science & Technology, 46(9), 1793-1800. doi:10.1111/j.1365-2621.2011.02670.xKofink, M., Papagiannopoulos, M., & Galensa, R. (2007). (-)-Catechin in Cocoa and Chocolate: Occurence and Analysis of an Atypical Flavan-3-ol Enantiomer. Molecules, 12(7), 1274-1288. doi:10.3390/12071274Kongor, J. E., Hinneh, M., de Walle, D. V., Afoakwa, E. O., Boeckx, P., & Dewettinck, K. (2016). Factors influencing quality variation in cocoa (Theobroma cacao) bean flavour profile â A review. Food Research International, 82, 44-52. doi:10.1016/j.foodres.2016.01.012Kopp G. M. Hennen J. C. Seyller M. &Brandstetter B.(2010).Process for producing high flavour cocoa. EP2241190A1.Kruszewski, B., & ObiedziĆski, M. W. (2020). Impact of Raw Materials and Production Processes on Furan and Acrylamide Contents in Dark Chocolate. Journal of Agricultural and Food Chemistry, 68(8), 2562-2569. doi:10.1021/acs.jafc.0c00412Lan, X., Liu, P., Xia, S., Jia, C., Mukunzi, D., Zhang, X., ⊠Xiao, Z. (2010). Temperature effect on the non-volatile compounds of Maillard reaction products derived from xyloseâsoybean peptide system: Further insights into thermal degradation and cross-linking. Food Chemistry, 120(4), 967-972. doi:10.1016/j.foodchem.2009.11.033Li, Y., Feng, Y., Zhu, S., Luo, C., Ma, J., & Zhong, F. (2012). The effect of alkalization on the bioactive and flavor related components in commercial cocoa powder. Journal of Food Composition and Analysis, 25(1), 17-23. doi:10.1016/j.jfca.2011.04.010Li, Y., Zhu, S., Feng, Y., Xu, F., Ma, J., & Zhong, F. (2013). Influence of alkalization treatment on the color quality and the total phenolic and anthocyanin contents in cocoa powder. Food Science and Biotechnology, 23(1), 59-63. doi:10.1007/s10068-014-0008-5Lima, L. J. R., Kamphuis, H. J., Nout, M. J. R., & Zwietering, M. H. (2011). Microbiota of cocoa powder with particular reference to aerobic thermoresistant spore-formers. Food Microbiology, 28(3), 573-582. doi:10.1016/j.fm.2010.11.011MALEYKI, M. J. A., & ISMAIL, A. (2010). ANTIOXIDANT PROPERTIES OF COCOA POWDER. Journal of Food Biochemistry, 34(1), 111-128. doi:10.1111/j.1745-4514.2009.00268.xMartĂn, M. Ă., & Ramos, S. (2017). Health beneficial effects of cocoa phenolic compounds: a mini-review. Current Opinion in Food Science, 14, 20-25. doi:10.1016/j.cofs.2016.12.002Martin, M. A., Goya, L., & Ramos, S. (2013). Potential for preventive effects of cocoa and cocoa polyphenols in cancer. Food and Chemical Toxicology, 56, 336-351. doi:10.1016/j.fct.2013.02.020MĂ©ndez-Albores, A., De JesĂșs-Flores, F., Castañeda-Roldan, E., ArĂĄmbula-Villa, G., & Moreno-MartıÌnez, E. (2004). The effect of toasting and boiling on the fate of B-aflatoxins during pinole preparation. Journal of Food Engineering, 65(4), 585-589. doi:10.1016/j.jfoodeng.2004.02.024Miller, K. B., Hurst, W. J., Payne, M. J., Stuart, D. A., Apgar, J., Sweigart, D. S., & Ou, B. (2008). Impact of Alkalization on the Antioxidant and Flavanol Content of Commercial Cocoa Powders. Journal of Agricultural and Food Chemistry, 56(18), 8527-8533. doi:10.1021/jf801670pOlam. (2017).The De Zaan cocoa manual. The Netherlands: Archer Daniels Midland Company BV.ODUNS, A. A., & LONGE, O. G. (1998). Nutritive value of hot water- or cocoa-pod ash solution-treated cocoa bean cake for broiler chicks. British Poultry Science, 39(4), 519-525. doi:10.1080/00071669888700Ofosu, I. W., Ankar-Brewoo, G. M., Lutterodt, H. E., Benefo, E. O., & Menyah, C. A. (2019). Estimated daily intake and risk of prevailing acrylamide content of alkalized roasted cocoa beans. Scientific African, 6, e00176. doi:10.1016/j.sciaf.2019.e00176Okiyama, D. C. G., Navarro, S. L. B., & Rodrigues, C. E. C. (2017). Cocoa shell and its compounds: Applications in the food industry. Trends in Food Science & Technology, 63, 103-112. doi:10.1016/j.tifs.2017.03.007Ortega, N., Romero, M.-P., MaciĂ , A., Reguant, J., AnglĂšs, N., MorellĂł, J.-R., & Motilva, M.-J. (2008). Obtention and Characterization of Phenolic Extracts from Different Cocoa Sources. Journal of Agricultural and Food Chemistry, 56(20), 9621-9627. doi:10.1021/jf8014415Pia, A. K. R., Pereira, A. P. M., Costa, R. A., Alvarenga, V. O., Freire, L., Carlin, F., & SantâAna, A. S. (2019). The fate of Bacillus cereus and Geobacillus stearothermophilus during alkalization of cocoa as affected by alkali concentration and use of pre-roasted nibs. Food Microbiology, 82, 99-106. doi:10.1016/j.fm.2019.01.009Quelal-VĂĄsconez, M. A., Lerma-GarcĂa, M. J., PĂ©rez-Esteve, Ă., Arnau-Bonachera, A., Barat, J. M., & Talens, P. (2020). Changes in methylxanthines and flavanols during cocoa powder processing and their quantification by near-infrared spectroscopy. LWT, 117, 108598. doi:10.1016/j.lwt.2019.108598QuelalâVĂĄsconez, M. A., LermaâGarcĂa, M. J., PĂ©rezâEsteve, Ă., Talens, P., & Barat, J. M. (2020). Roadmap of cocoa quality and authenticity control in the industry: A review of conventional and alternative methods. Comprehensive Reviews in Food Science and Food Safety, 19(2), 448-478. doi:10.1111/1541-4337.12522Razzaque, M. A., Saud, Z. A., Absar, N., Karim, M. R., & Hashinaga, F. (2000). Purification and Characterization of Polyphenoloxidase from Guava Infected with Fruit-rot Disease. Pakistan Journal of Biological Sciences, 3(3), 407-410. doi:10.3923/pjbs.2000.407.410Rimbach, G., Melchin, M., Moehring, J., & Wagner, A. (2009). Polyphenols from Cocoa and Vascular HealthâA Critical Review. International Journal of Molecular Sciences, 10(10), 4290-4309. doi:10.3390/ijms10104290RodrĂguez, P., PĂ©rez, E., & GuzmĂĄn, R. (2009). Effect of the types and concentrations of alkali on the color of cocoa liquor. Journal of the Science of Food and Agriculture, 89(7), 1186-1194. doi:10.1002/jsfa.3573Saltini, R., Akkerman, R., & Frosch, S. (2013). Optimizing chocolate production through traceability: A review of the influence of farming practices on cocoa bean quality. Food Control, 29(1), 167-187. doi:10.1016/j.foodcont.2012.05.054Sarmadi, B., Aminuddin, F., Hamid, M., Saari, N., Abdul-Hamid, A., & Ismail, A. (2012). Hypoglycemic effects of cocoa (Theobroma cacao L.) autolysates. Food Chemistry, 134(2), 905-911. doi:10.1016/j.foodchem.2012.02.202Sarmadi, B., Ismail, A., & Hamid, M. (2011). Antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of cocoa (Theobroma cacao L.) autolysates. Food Research International, 44(1), 290-296. doi:10.1016/j.foodres.2010.10.017Scalone, G. L. L., Textoris-Taube, K., De Meulenaer, B., De Kimpe, N., Wöstemeyer, J., & Voigt, J. (2019). Cocoa-specific flavor components and their peptide precursors. Food Research International, 123, 503-515. doi:10.1016/j.foodres.2019.05.019Schroder, T., Vanhanen, L., & Savage, G. P. (2011). Oxalate content in commercially produced cocoa and dark chocolate. Journal of Food Composition and Analysis, 24(7), 916-922. doi:10.1016/j.jfca.2011.03.008Shankar, M. U., Levitan, C. A., Prescott, J., & Spence, C. (2009). The Influence of Color and Label Information on Flavor Perception. Chemosensory Perception, 2(2), 53-58. doi:10.1007/s12078-009-9046-4Singh, P., Kesharwani, R. K., & Keservani, R. K. (2017). Antioxidants and Vitamins. Sustained Energy for Enhanced Human Functions and Activity, 385-407. doi:10.1016/b978-0-12-805413-0.00024-7Tanaka M. &Terauchi M.(1999).Cocoa powder rich in polyphenols process for producing the same and modified cocoa containing the same. US6485772B1.TaĆ, N. G., & Gökmen, V. (2016). Effect of alkalization on the Maillard reaction products formed in cocoa during roasting. Food Research International, 89, 930-936. doi:10.1016/j.foodres.2015.12.021Terink J. &Brandon M. J.(1981).Alkalized cocoa powders and foodstuffs containing such powders. US4435436A.Todorovic, V., Milenkovic, M., Vidovic, B., Todorovic, Z., & Sobajic, S. (2017). Correlation between Antimicrobial, Antioxidant Activity, and Polyphenols of Alkalized/Nonalkalized Cocoa Powders. Journal of Food Science, 82(4), 1020-1027. doi:10.1111/1750-3841.13672Tomas-BarberĂĄn, F. A., Cienfuegos-Jovellanos, E., MarĂn, A., Muguerza, B., Gil-Izquierdo, A., CerdĂĄ, B., ⊠EspĂn, J. C. (2007). A New Process To Develop a Cocoa Powder with Higher Flavonoid Monomer Content and Enhanced Bioavailability in Healthy Humans. Journal of Agricultural and Food Chemistry, 55(10), 3926-3935. doi:10.1021/jf070121jTotlani, V. M., & Peterson, D. G. (2005). Reactivity of Epicatechin in Aqueous Glycine and Glucose Maillard Reaction Models:â Quenching of C2, C3, and C4 Sugar Fragments. Journal of Agricultural and Food Chemistry, 53(10), 4130-4135. doi:10.1021/jf050044xTotlani, V. M., & Peterson, D. G. (2006). Influence of Epicatechin Reactions on the Mechanisms of Maillard Product Formation in Low Moisture Model Systems. Journal of Agricultural and Food Chemistry, 55(2), 414-420. doi:10.1021/jf0617521Trout R. B.(2001).Method for making dutched cocoa. EP1278428B1.Turcotte, A.-M., Scott, P. M., & Tague, B. (2013). Analysis of cocoa products for ochratoxin A and aflatoxins. Mycotoxin Research, 29(3), 193-201. doi:10.1007/s12550-013-0167-xWang, R., Wang, T., Zheng, Q., Hu, X., Zhang, Y., & Liao, X. (2012). Effects of high hydrostatic pressure on color of spinach purĂ©e and related properties. Journal of the Science of Food and Agriculture, 92(7), 1417-1423. doi:10.1002/jsfa.4719Wiant M. J. William R. Lynch W. R. &LeFreniere R. C.(1989).Method for producing deep red and black cocoa. US5009917A.Wissgott U.(1988).Process of alkalization of cocoa in aqueous phase. US4784866A.Wollgast, J., & Anklam, E. (2000). Review on polyphenols in Theobroma cacao: changes in composition during the manufacture of chocolate and methodology for identification and quantification. Food Research International, 33(6), 423-447. doi:10.1016/s0963-9969(00)00068-5Zhang, L., Xia, Y., & Peterson, D. G. (2014). Identification of Bitter Modulating Maillard-Catechin Reaction Products. Journal of Agricultural and Food Chemistry, 62(33), 8470-8477. doi:10.1021/jf502040eZhu, Q. Y., Holt, R. R., Lazarus, S. A., Ensunsa, J. L., Hammerstone, J. F., Schmitz, H. H., & Keen, C. L. (2002). Stability of the Flavan-3-ols Epicatechin and Catechin and Related Dimeric Procyanidins Derived from Cocoa. Journal of Agricultural and Food Chemistry, 50(6), 1700-1705. doi:10.1021/jf011228
Moduli Spaces for Four- and Five- Dimensional Black Holes
We propose a universal expression for the moduli metric of a class of four-
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These include the black holes that are associated with various intersecting
branes in ten and eleven dimensions, the electrically charged black holes of
N=2 D=5 and N=2 D=4 supergravities with any number of vector multiplets, and
dyonic black holes of N=2 D=4 supergravity. The moduli metric of electrically
charged N=2 D=4 black holes coupled to any number of vector multiplets is
explicitly computed. We also investigate the superconformal symmetries of the
black hole moduli spaces for small black hole separations.Comment: 44 pages, phyzzx.tex, minor corrections, some more references adde
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the first KATRIN neutrino mass analyses, as well as a D gas mixture of 96%
purity used in KATRIN commissioning runs. The achieved precision on the
energy-loss function has abated the corresponding uncertainty of
[arXiv:2101.05253] in the KATRIN
neutrino-mass measurement to a subdominant level.Comment: 12 figures, 18 pages; to be submitted to EPJ
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