Functional, Physicochemical and Nutritional Properties of Protein from Klunzinger's Ponyfish Extracted by the pH Shifting Method

Abstract

Functional, physicochemical and nutritional properties of protein from whole Klunzinger's ponyfish (Equulites klunzingeri) extracted by pH shifting methods were evaluated. The alkaline protein isolate (AlPI) had higher protein content (88.69 %) than the acid protein isolate (AcPI, 86.13%). AlPI had generally higher content of essential amino acid than AcPI, except methionine. The ratio of total essential amino acid/total amino acid in AlPI and AcPI of Klunzinger's ponyfish was found to be 47.5 and 44.9%, respectively. According to differential scanning calorimetry analysis, the Tmax values of raw Klunzinger's ponyfish (R), AlPI and AcPI were determined to be 40.4, 71.2 and 70.44C, respectively. The initial thiobarbituric acid reactive substance value was higher in AcPI (1.99) than that in AlPI (1.19). AlPI was also found to be lighter and whiter than AcPI (L*: 66.56, whiteness: 59.50 and L*: 60.76, whiteness: 56.41, respectively). The results of "emulsion capacity," "water-and oil-holding capacity" and "foam capacity and stability" of AlPI and AcPI indicated that satisfactory functional properties are needed in food processing. PRACTICAL APPLICATIONSKlunzinger's ponyfish is a discard fish that exists in large amount in Mediterranean Sea. Even if it has a potential as high quality protein source, it is not being used for human food products as functional ingredients. This study investigates the functional, physicochemical and nutritional properties of protein from whole Klunzinger's ponyfish extracted by pH shifting methods. According to the obtained data in this study, the nutritional, functional and physicochemical properties of protein isolates of Klunzinger's ponyfish were suitable for supplementing as an ingredient for human consumption. Protein as an ingredient developed from an inexpensive source is important to the industry.Notes: The values are expressed as mean and standard deviation, n = 3. Means followed by different superscript letters are significantly different (P < 0.05). † Essential amino acid for humans. AA, amino acid; EAA, essential amino acid.

Functional properties and dynamic rheology of protein isolates extracted from male and female common carp (Cyprinus carpio) muscle subjected to pH‐shifting method

“…BPI had lower Fc than API for both male and female. Fc of 9.0%, 2.41%, and 7.77%, respectively, for RF, ALPI, and AcPI was observed for Klunzinger's pony FPIs (Özyurt et al, ). The Fc in present study was in lieu of studies conducted by Chomnawang &Yongsawatdigul () and Chen and Jaczynski ().…”

“…The statistical analysis revealed significant variation in WAC as result of isolate preparation method as well as gender differences ( p < .005). The ALPI and AcPI from Klunzinger's ponyfish had WAC of 2.36 and 2.58 ml/g, respectively (Özyurt et al, ). Foh et al () reported similar WHC values i.e., 2.51 and 2.63 ml/g for ALPI and ACPI, respectively, extracted from tilapia fish.…”

“…The presence of higher charge on proteins lowered hydrophobic interaction, while enhanced solubility as well as flexibility provided a greater opportunity to the proteins to spread rapidly on the air–water interface, enclosing air and thus led to more FC (Shevkani et al, ). Özyurt et al () reported that FC of ALPI and AcPI isolated from whole Klunzinger's ponyfish was 34.5% and 28.05%, respectively. FS for BPI was 75.33% and 52.33% for male APIs was observed, while FC of 83.67% for BPIs and 62.33% for female API was observed (Table ).…”

“…The second method involves the solubilization of muscular proteins at acidic pH (2.5) followed by precipitation at isoelectric point (5.5) (Hultin & Kelleher, ). The method of solubilization and selection of fish species largely affect the nutritional as well as functional properties of fish muscle proteins (Özyurt, Şimşek, Karakaya, Aksun, & Yeşilsu, ). It has been demonstrated that prolonged exposure to acidic or alkaline conditions may deteriorate the functionality of muscular proteins (Fraqueza, Cardoso, Ferreira, & Barreto, ).…”

“…Protein isolates have potential for the development of new class of food formulations having appreciable nutritional properties (Lone, Wani, Wani, & Masoodi, ). Fundamentally, the processing of muscle by pH‐shift method removes membrane lipids thereby provides stability to edible proteins against oxidation as well as cause reduction in the fat soluble toxins (Özyurt et al, ). The functional foods are those food products, which possess added, technologically developed ingredients having particular health benefits and these can also be fulfilled by muscle protein isolates (Tahergorabi, Beamer, Matak, & Jaczynski, ).…”