Recovery of Proteins from Rohu Processing Waste Using pH Shift Method: Characterization of Isolates

Abstract

Yield and physicochemical characteristics of protein isolates recovered from rohu processing waste by acid and alkali-aided protein solubilization were studied. pH 2.0 from acidic side and pH 13.0 from alkaline side resulted in maximum protein solubility, whereas minimum solubility was observed at pH 5.5. Except for pH 13.0, theoretical protein recovery was more than the actual recovery after centrifugation. Maximum protein recovery after the first centrifugation cycle was observed for pH 2.0 and pH 13.0, and the maximum protein recovery during the second centrifugation cycle was observed at precipitation pH 5.5 in both acidic and alkaline methods. Acidic and alkaline methods resulted in a total process recovery of 31.81±0.001% and Downloaded by [University of Cambridge] at 11:A c c e p t e d M a n u s c r i p t 2 31.11±0.01%, respectively. Isolates prepared by acidic method had more whiteness and high foaming capacity, whereas isolates prepared using alkaline methods had less whiteness, tough texture, and high foaming stability. No microbial counts were detected in any of the isolates. Acid and alkaline methods described in this study can be used for the recovery of proteins from rohu processing waste with good yields and functionality.

Physicochemical and functional characteristics of proteins treated by a pH‐shift process: a review

“…The yields of protein recovered by alkaline‐aided shift process were higher compared with those of protein recovered by acid‐aided shift process, which could reach up to 60%. Some studies indicate that acid‐aided shift process can lead to higher protein yield, whereas other researches show that higher yield of protein treated by alkaline‐aided shift process is observed (Shabanpour et al ., 2015a,b; Surasani et al ., 2017a,b, Surasani et al, 2018). The difference of protein yield is mainly due to the denaturation extent of proteins and the compositions of raw fishery proteins (Surasani, 2018).…”

“…After pH of fishery mixture is adjusted back to isoelectric point, the net charges in proteins decrease to the minimum. The structural, physicochemical and functional characteristics of fishery proteins recovered by pH‐shift process are significantly impacted (Surasani et al ., 2017a,b; Sun et al ., 2019; Zhou & Yang, 2019).…”

“…pH‐shift process can significantly affect the solubility of fishery proteins (Table 1). Generally, fishery proteins show the high solubility at pH 1.0–3.0 or 11.0–13.0 during pH‐shift process, whereas it presents low solubility between pH 5.0 and 6.0 due to low solubility of myosin at these pH ranges (Marmon & Undeland, 2013; Surasani et al ., 2017a,b; Abdollahi & Undeland, 2019). Rawdkuen et al .…”

Effect of organic acid on recovery yields and characteristics of rohu (Labeo rohita) protein isolates extracted using pH shift processing

“…With this aim, a methodology called pH shift process was developed by Hultin and Kelleher that enabled the effective protein recovery from underutilized by‐products and processing waste. Thereafter, many studies have been conducted on protein recovery from low‐cost fish, fish by‐products and processing waste through a pH shift process, to obtain their characterization and application . Almost all the studies used hydrochloric acid (HCl) and sodium hydroxide (NaOH) for protein solubilization during acid‐ and alkali‐aided extraction processes.…”

“…Thereafter, many studies have been conducted on protein recovery from low-cost fish, fish by-products and processing waste through a pH shift process, to obtain their characterization and application. [6][7][8][9][10] Almost all the studies used hydrochloric acid (HCl) and sodium hydroxide (NaOH) for protein solubilization during acid-and alkali-aided extraction processes. Many studies reported that proteins recovered using HCl in acid-aided solubilization showed greater denaturation and associated loss in functionality over alkali-aided solubilization.…”