Peroxidase and polyphenoloxidase activity in tomato in natura and tomato purée

Abstract

ABSTRACT. Oxidative enzymes are responsible for changes in flavor, texture, color and also in some nutritive properties of several fruits and vegetables processed in industries. The present investigation aimed to study the activity of Peroxidase (E.C. 1.11.1.7) and Polyphenoloxidase (E.C. 1.10.3.1) in tomato fresh pulp in natura and in three different trademarks of tomato purée sold in supermarkets. Crude extracts of peroxidase (POD) and polyphenoloxidase (PPO) enzymes, from both fresh tomato pulp in natura and processed tomato purée, purchased in supermarkets, were prepared, by using sodium phosphate buffer at different pHs. The best pH values for extraction of peroxidase and polyphenoloxidase were 6.2 and 7.5, respectively. Protein precipitations were carried out using acetone at the ratio of 1:2 enzymatic extract/acetone. The enzymatic extract from Santa Clara tomato cultivar was concentrated 10 times, before being applied to the chromatographic column packed with Sephacryl 100-HS. From the samples eluted, one isoenzyme was isolated (A 1 ) and the molecular weight and isoelectric point (pI) was determined (MW 45 kDa and pI 4.5). The fraction with A 1 was stored at -18 o C, and later used for thermostability studies. A decrease in the enzymatic activity was observed at 85 and 90C, in the enzymatic extracts obtained from fresh tomato pulp; nevertheless, in the processed tomato purées the loss of activity was more significant.

Effect of production system and inhibitory potential of aroma volatiles on polyphenol oxidase and peroxidase activity in tomatoes

“…In earlier studies, the optimal pH values of tomato PPO and POD enzymes were 7.0 and 6.2 with catechol and o ‐dianisidine as substrates, respectively. Similarly, pH 4.8 was reported to be optimal for tomato PPO by using 3,4‐dihydroxyphenylacetic acid as a substrate 9, 20 …”

“…One‐fourth of total tomato consumption is consumed in its processed form 1 . During the processing of tomato products such as puree, thermal treatment is the favored method to inactivate oxidative enzymes 20 . However, little is known about the thermal inactivation of PPO and POD enzymes in tomatoes.…”

“…Beside enzymatic browning, PPO and POD enzymes play a considerable role in plant defense and in several metabolic processes 16, 17 . In tomatoes, PPO and POD activity has been studied in the context of stress tolerance and resistance to pathogens 4, 18–20 . In recent years, the cultivation of tomatoes in protected environments has increased to maintain the demand and supply throughout the year.…”

Qualidade pós-colheita da banana 'Prata Catarina' submetida a diferentes danos mecânicos e armazenamento refrigerado

“…Utilizou-se análise descritiva para os dados de coloração do fruto e atividade enzimatica da PPO. (CHITARRA & CHITARRA, 2005), pois a elevada atividade enzimática ocasiona, além do escurecimento, perdas nutricionais, mudanças indesejáveis no aroma, sabor, textura e cor dos frutos (MANTOVANI & CLEMENTE, 2010). Efeito negativo de danos por impacto e corte também foi observado em maçãs 'Fuji Suprema', na qual, promoveu o escurecimento da polpa no local lesionado (HENDGES et al, 2011).…”

Postharvest behavior and lycopene content of tomatoes at different harvest times

“…During the growth and development period, there are many chemical and physical changes occurred in tomato that have an impact on fruit quality and ripening behavior after harvest (Dhall & Singh, 2016) and in the storage, either for commercialization or for consumption, the tomato will undergo modifications, resulting in reduced sensorial quality, loss of fresh mass, decrease in firmness and fruit acidification (Ferreira et al, 2010), due oxidative enzymes contribute to changes in taste, texture, color and some nutritional properties of fruits (Mantovani & Clemente, 2010).…”