BRS Violeta grape (BRS Rúbea x IAC 1398-21) and jambolan (Syzygium cumini (L.)): study of chemical and biochemical changes in the production of dehydrated juice by the foam mat drying process

Author(s)

Iasnaia Maria de Carvalho Tavares

• Document type: Doctoral Thesis
• Press: São José do Rio Preto. 2017-05-31.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2017-03-31
• Advisor: Roberto da Silva; Ellen Silva Lago Vanzela; Isidro Hermosín Gutiérrez

Abstract

Jambolan (Syzygium cumini (L.)) and BRS Violeta (BRS Rúbea x IAC 1398-21) cultivar grapes are fruits with the potential for the development of dehydrated products with a high concentration of phenolic compounds. And so, this study consisted of three main objectives: (a) to obtain dehydrated products from the jambolan and BRS Violeta grape juices using the foam mat drying process by hot air at 60, 70 and 80 ° C and lyophilization (control); (b) study the chemical (total phenolic compounds (TPC), antioxidant activity (AA)), physical (color) and biochemical (enzymatic activity of polyphenol oxidase (PPO), peroxidase (POD) and pectinamethylesterase (PME)) changes after processing the fruit into juice and then dehydrated products; and (c) to study the qualitative and quantitative changes in the phenolic compounds after processing the fruit into juices and then dehydrated products, as well as during storage of the dehydrated products (150 days at 4, 25 and 35 °C) using high-performance liquid chromatography with a diode array detector coupled to a mass spectrometer with an electrospray ionization system (HPLC-DAD-EIS-MS/MSn), To obtain the dehydrated products, fruit juices were first obtained and these were added into formulations containing emulsifiers, stabilizers and anti-humectants in order to obtain stable foams suitable for the drying process. After drying at the three temperatures, it was found, for both fruits, that the foams dehydrated faster at 80 °C but still presented a concentration of phenolic compounds similar to those obtained at 60 and 70 °C. PPO, POD and PME were present in the two fruits and, after their processing to obtain the juices, there were significant reductions in their activities, mainly the PPO and POD of the BRS Violeta grape. For the dehydrated products of both fruits, there was total (100%) inactivation of all three enzymes. In both the jambolan and grape juices, there was a greater degradation of the anthocyanins than of the flavonols, however, there was a positive effect on the derivatives of the hydroxycinnamic acids (DAHC) of the grapes and on the hydrolysable tannins of the jambolan. In the dehydrated products obtained from the two fruits, drying at 70 ° C was the most adequate in terms of preservation of the phenolic compounds and reduction of the process time. The anthocyanins were negatively affected by the elevation of the drying temperature and the DAHC and flavonols were more sensitive to oxidative processes and the hydrolysable tannins were more sensitive to the heating time in the dehydration step. Despite the degradation that occurred during processing, the products did not differ much in their qualitative profile of phenolic compounds and still presented a considerable TPC concentration and good AA. As for the color characteristics, the dehydrated products from jambolan juice had coloring tending to violet and those from grapes tending to red. The storage of dehydrated products over 150 days at 4, 25 and 35 °C showed that the phenolic compounds present in the dehydrated product obtained from the jambolan juice were more stable than those present in the product obtained from the grape juice. Although there were losses of phenolic compounds in the dehydrated products, especially anthocyanins at 35 °C (36-45% and 8-9% for grapes and jambolan, respectively), both products still had considerable final concentrations of phenolic compounds, which should encourage further studies of their use as healthy ingredients in different food products. (AU)

• FAPESP's process: 13/19057-2 - Grape BRS Violet (BRS Rúbea x IAC 1398-21) and Jambolão (Syzygium cumini (L.)): study of biochemical and chemical changes in the production of dried juice by the foam-mat drying method
• Grantee: Iasnaia Maria de Carvalho Tavares
• Support Opportunities: Scholarships in Brazil - Doctorate