  Citation: Chanted, J.; Panpipat, W.; Cheong, L.-Z.; Chaijan, M. Recovery of Functional Proteins from Pig Brain Using pH-Shift Processes. Foods 2022, 11, 695. https://doi.org/10.3390/ foods11050695 Academic Editor: Alaa El-Din A. Bekhit Received: 9 February 2022 Accepted: 24 February 2022 Published: 26 February 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). foods Article Recovery of Functional Proteins from Pig Brain Using pH-Shift Processes Jaruwan Chanted 1 , Worawan Panpipat 1 , Ling-Zhi Cheong 2 and Manat Chaijan 1, * 1 Food Technology and Innovation Research Center of Excellence, School of Agricultural Technology and Food Industry, Walailak University, Nakhon Si Thammarat 80160, Thailand; jaruwanchanted@gmail.com (J.C.); pworawan@wu.ac.th (W.P.) 2 Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, College of Food and Pharmaceutical Science, Ningbo University, Ningbo 315211, China; cheonglingzhi@nbu.edu.cn * Correspondence: cmanat@wu.ac.th; Tel.: +66-7567-2384; Fax: +66-7567-2302 Abstract: The goal of this work is to explore if pH-shift processing could be used as a cold refinery technique to manufacture pig brain protein isolate (PI). Pig brain protein had the highest solubility at pH 2 (acid method) and pH 12 (alkaline method). As the protein solution’s zeta-potential was near 0 with the lowest solubility, pH 5.0 was chosen as the precipitation pH. Alkaline process produced a 32% dry matter yield with phospholipid content of 35 mg/100 g. The alkaline-made PI was better at forming soft gels and had good emulsifying and foaming capabilities. Although the acid-made PI included less residual lipid and total haem protein and was whiter in colour, it could not be gelled. Acid-made PI was more prone to lipid oxidation with a poorer ability to function as an emulsifier and foaming agent. Thus, functional proteins from pig brain may be isolated using the alkaline pH-shift technique. Keywords: pH-shift; protein isolate; pig brain; by-product; functionality 1. Introduction The issue of food sustainability and food security has existed among human societies due to an expanding worldwide population, and an increase in food demand is projected by 2050, leading to a lack of animal-based protein supply from farmed livestock [1]. The world’s food demand will be over 60% higher by 2050 than it is today [2]. As a consequence, researchers have been looking for a sustainable food supply chain [3]. Proteins are indeed an essential ingredient for life and provide technological utility to food products. One of the solutions for this is to fully utilise protein-containing by-products from livestock slaughtering and processing. In 2020, Thailand’s pig production is expected to exceed 20.5 million heads, with pork consumption expected to total 1.3 million tons [4]. Increased pork consumption produces by-products such as blood, bone, bristle, fat trimming, viscera, and brain [5–7]. Between 60 and 70% of the slaughtered carcass is made up of by-products, with around 40% edible and 20% inedible [7]. Some of these by-products are traditionally used in some countries around the world in a variety of recipes [6] and can be effectively value-added using additional processes such as thermal, chemical, centrifugation, washing, and combined processes to produce lard, flavour concentrate, plasma, red blood cells, gelatin, protein hydrolysates, and others [7–9]. However, a range of factors, such as religion, culture, income, and personal taste, have an impact on the utilisation of meat by-products. Various meat by-products can be deemed edible in some areas but inedible in others, depending on the region and local traditions. In actuality, some countries use high-nutrient by-products such as heart, liver, blood, lung, spleen, kidney, tripe, and brains in their cuisines [6]. Despite the fact that pig brain is a common by-product of slaughtering and pork processing, Foods 2022, 11, 695. https://doi.org/10.3390/foods11050695 https://www.mdpi.com/journal/foods