POLYPHENOL OXIDASE AND PEROXIDASE ENZYME ASSAYS IN SWEET POTATO CULTIVARS HARVESTED AT DIFFERENT TIMES

Authors

  • Samara Lopes de Almeida Department of Production Vegetable, Universidade Federal Rural de Pernambuco, Serra Talhada, PE http://orcid.org/0000-0001-7820-6488
  • Maria Aparecida dos Santos Morais Department of Production Vegetable, Universidade Federal Rural de Pernambuco, Serra Talhada, PE http://orcid.org/0000-0003-3529-5198
  • José Ricardo Tavares de Albuquerque Department of Plant Science, Universidade Federal Rural do Semi-Árido, Mossoró, RN http://orcid.org/0000-0003-4113-1501
  • Aurélio Paes Barros Júnior Department of Plant Science, Universidade Federal Rural do Semi-Árido, Mossoró, RN http://orcid.org/0000-0002-6983-8245
  • Adriano do Nascimento Simões Department of Production Vegetable, Universidade Federal Rural de Pernambuco, Serra Talhada, PE http://orcid.org/0000-0001-8438-2621
  • Kelem Silva Fonseca Department of Production Vegetable, Universidade Federal Rural de Pernambuco, Serra Talhada, PE http://orcid.org/0000-0002-7136-8748

DOI:

https://doi.org/10.1590/1983-21252019v32n226rc

Keywords:

Ipomoea batatas L. (Lam.). Standardization. Minimum processing.

Abstract

Enzyme assays are based on methodologies described in the literature. However, the enzyme kinetics must be adjusted to obtain more reliable results. This study aimed to adjust assays by testing different polyphenol oxidase (PPO) and peroxidase (POD) extract amounts and reaction times in sweet potato cultivars harvested at different times. Sweet potato cultivars Paraná, Mãe de Família, and ESAM1 were harvested at 120, 150, and 180 days after planting and minimally processed. A 0.25 g sample was used to determine PPO and POD activities immediately after minimal processing at each harvest. Extraction was performed in 1500 μL phosphate buffer (0.2 M, pH 6.0). The PPO assay was performed by adding 10–50 μL extract, 1490–1450 μL phosphate buffer (0.2 M, pH 6.0), and 1500 μL catechol (0.2 M). The POD assay was carried out by adding 10–50 μL extract to a reaction medium containing 1790–1750 μL phosphate buffer (0.2 M, pH 6), 100 μl guaiacol (5 g L-1), and 100 μL hydrogen peroxide (0.8 g L-1). In both cases, the evaluated reaction times were 1, 2, and 3 min. In the three cultivars, PPO and POD activities increased with the volume of extract and reaction time at all harvest times. The enzyme extract volume of 10 μL for 2 min promoted a continuous increase in PPO and POD enzyme activities in all studied cultivars and at all reaction times.

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Published

22-05-2019

Issue

Section

Food Engineering