Screening, separating, and completely recovering polyphenol oxidases and other biochemicals from sweet potato wastewater in starch production

Abstract

Polyphenol oxidase (PPO) has multiple functions, and the lack of commercially available enzyme sources limits its widespread application in various industries. An accurate PPO assay was developed by HPLC determination of the substrate oxidation. Resources screening indicated that sweet potato (Ipomoea batatas L.) wastewater in starch production has high PPO activity. A procedure was developed for separately recovering PPO, β-amylase, sporamins, and small molecular nutrients (SMNs) from sweet potato wastewater. The wastewater was adjusted to pH 3.5 to precipitate PPO, and then adjusted to 50 % acetone to precipitate β-amylase and further to 80 % acetone to precipitate sporamins. The SMNs were obtained after acetone recovery. Purified powders of 4.3 × 10(5) units of PPO, 4.0 × 10(6) units of β-amylase, 8.70 g sporamins, and 20.2 g SMNs were obtained from the wastewater of 1 kg sweet potato. More than 50 million tons of sweet potato is used for starch production annually around the world. Through this simple procedure, huge amount of biochemical resources can be recovered from the wastewater, which greatly increases the economic value of the crop and saves the environment.

Recovery of High Value‐Added Nutrients from Fruit and Vegetable Industrial Wastewater

“…Precipitation is one of the most popular technologies that play an important role in protein and enzyme recovery normally using salts, polyelectrolytes, and organic solvents as precipitants and isoelectric precipitation. However, it may lead to risk of denaturation and products usually require further purification due to the precipitation which is not very selective (Cheng et al., ). Now, studies have focused on nitrogen and phosphorus recovery from industrial wastewater (Sengupta, Nawaz, & Beaudry, ), and unfortunately few studies on protein recovery from the wastewater that is similar to wastewater of FVPI, rich in macromolecule organic components, can be used as the reference (Yang, Sun, Mengyan, & Wang, ).…”

“…Polyphenol oxidase (PPO) is a group of Cu‐containing enzymes that can catalyze the oxidation of phenols to o ‐quinones and cause undesirable enzymatic browning in fresh‐cut fruits (Mayer, ; Taranto et al., ). The PPOs have multiple functions and have been widely applied in a range of industries, such as in organic synthesis, the treatment of industrial dyes, wastewaters, pulp, and paper bleaching, and in the removal of phenolics to increase the stability of beverages (Cheng et al., ). PPOs are typically nutrients richly present in potato starch‐processing waste.…”

“…A method for recovering PPOs used pH adjustment for PPO precipitation and separation of both PPO and β‐amylase from sporamins by 50% acetone and precipitation of sporamins by 80% acetone. This process resulted in 4.3 × 10 5 units of PPO, 4.0 × 10 6 units of β‐amylase, and 8.70 g sporamins (Cheng et al., ).…”

Preparation of peroxidase and phenolics using discarded sweet potato old stems

“…Different precipitation methods, including isoelectric point precipitation (pH 3.0–10.0), ammonium sulfate precipitation (10–80%) and ethanol precipitation (20–80%) were tested for the efficiency of precipitating and separating peroxidases, as previous reported 29 .…”

Extraction and profiling of proteins in yellow powder from sweet potato starch wastewater using response surface methodology and proteomic approach

“…Therefore, for assessing the potential applications of recovered proteins and increasing their added value, it is of paramount importance to characterize the fractions of recovered proteins. To the best of our knowledge, despite a number of bioactive proteins from the wastewater, including polyphenol oxidase (PPO), β-amylase, and sporamin, were identified and isolated (Cheng et al, 2015;Li et al, 2018), total protein fractions from the wastewater have not been characterized to date.…”