Comparison of the biochemical properties and thermal inactivation of polyphenol oxidase from three lily bulb cultivars

Abstract

The biochemical properties and thermal inactivation of polyphenol oxidase (PPO) from three main planted lily cultivars in China, namely, Lilium lancifolium Thunb, Lilium brownie var. viridulum, and Lilium davidii var. unicolor cotton were evaluated. Data indicate that the PPO from three cultivars showed two optimum pH levels of 4.0 and 6.5-7.0 and temperature of 15°C and exhibited the highest affinity toward 4-methylcatechol. However, this enzyme did not exhibit monophenolase activity. Thiourea and L-cysteine were more effective than other inhibitors. The enzymatic activity of L. lancifolium Thunb PPO crude extract was higher than that of L. brownie var. viridulum and L. davidii var. unicolor cotton. For thermal inactivation, L. davidii var. unicolor cotton PPO showed the best thermal resistance at 65-75°C, and L. lancifolium Thunb showed stability at 45°C. The deactivation of the three types of PPO followed the first-order reaction kinetics, and the activation energy (E a) was 144.28, 138.00, and 107.12 kJ/mol for L. lancifolium Thunb PPO, L. brownie var. viridulum PPO, and L. davidii var. unicolor cotton PPO, respectively. Practical applications Lilium is an ornamental and edible plant typically used for food and traditional Chinese medicine. Its flowers are used for decoration, and its underground bulbs are rich in various bioactive substances. Fresh lily bulbs easily turn brown and lose economic value during storage and processing. Polyphenol oxidase (PPO) is a crucial molecule involved in the enzymatic browning of fruit and vegetables. In this study, PPO was extracted from three main planted lily cultivars in China. Namely, Lilium lancifolium Thunb, Lilium brownie var. viridulum, Lilium davidii var. unicolor cotton and was partially characterized. The results are of considerable importance to further understand the PPO of lily bulbs and provide guidance for the inactivation of enzymes and the processing of lily bulb juice.

Purification and Characterization of a Dark Red Skin Related Dimeric Polyphenol Oxidase from Huaniu Apples

“…Researchers have also reported that 4-methylcatechol [ 29 ] and catechol [ 30 ] are the most suitable substrates for PPO purified from apples. Moreover, for the PPOs purified from round brinjal ( Solanum melongena ) [ 31 ], royal dates ( Ziziphus jujuba ) [ 32 ], lily bulb ( Lilium spp ) [ 33 ], and peach ( Prunus persica ) [ 34 ]' 4-methylcatechol is the most suitable substrate. Flavanols (mainly EC) and PCs are the most abundant phenolic substances in apples [ 8 , 10 ].…”

Effects of Ultrasonic Treatment on Physical Stability of Lily Juice: Rheological Behavior, Particle Size, and Microstructure

“…The refractive index value was set to 1.46. The average particle size was calculated by using the volume-weighted average diameter D [4,3] value and the area-weighted average diameter D [3,2] value [26].…”

“…At the same time, the rich taste and color greatly satisfy consumers' dietary needs. Lily is a perennial herbaceous bulbous plant belonging to the family Liliaceae, which is mainly distributed in the central part of Gansu Province, China [2,3]. Lilies can be divided into medicinal lily and edible lily, of which Lanzhou lily is the only sweet lily that can be used as both medicine and food.…”

Effects of Applying Nitrogen and Potassium on Lilium lancifolium Growth and Accumulation of Secondary Metabolites in Bulbs

“…Studies have shown that the underground bulbs are rich in various bioactive substances, such as total phenols, total flavonoids, polysaccharides, and saponins [2,3], which contribute to the quality and nutritional value. These compounds are known to have antitumor [4,5], anti-oxidation [6,7], hypoglycemic [8], and anti-inflammatory functions [9,10]. The bulb is an important vegetative reproductive organ for triploid L. lancifolium.…”