Endogenous Proteases in Pacific Whiting (Merluccius productus) Muscle as A Processing Aid in Functional Fish Protein Hydrolysate Production

A fish protein hydrolysate (FPH) from Pacific whiting (Merluccius productus) muscle was produced by autolysis of a minced homogenate (8% protein) at pH 7.0 and 60°C, where maximum endogenous proteolytic activity was detected. FPH production was controlled by the pH stat method, yielding a 4.43% degree of hydrolysis after 1 h of autolysis. Upon autolytic processing, 28.9 ± 0.7% of the total protein was found in the soluble fraction. FPH was 100% soluble at pH 7.0 and 10.0 and was less soluble at pH 4 (82.5%, P ≤ 0.05). FPH showed better emulsifying properties than sodium caseinate (SCA) at pH 4.0 (P ≤ 0.05), but had a lower foaming capacity (P ≤ 0.05) than bovine albumin (BSA) at all evaluated pHs. FPH foaming capacity was not affected by pH, however, foam stability was equal or better than that of BSA, especially at pH 4.0 (P ≤ 0.05). These results suggest the possibility of producing FPH with similar or better functional properties than those of functional ingredients, such as SCA and BSA. Furthermore, the data presented support our hypothesis that the high proteolytic activity in Pacific whiting could be used as an advantage in fish protein hydrolysate production or as a processing aid where protein hydrolysis is required.     

Plant proteases for bioactive peptides release: A review

ABSTRACT

Proteins are a potential source of health-promoting biomolecules with medical, nutraceutical, and food applications. Nowadays, bioactive peptides production, its isolation, characterization, and strategies for its delivery to target sites are a matter of intensive research. In vitro and in vivo studies regarding the bioactivity of peptides has generated strong evidence of their health benefits. Dairy proteins are considered the richest source of bioactive peptides, however proteins from animal and vegetable origin also have been shown to be important sources. Enzymatic hydrolysis has been the process most commonly used for bioactive peptide production. Most commercial enzymatic preparations frequently used are from animal (e.g., trypsin and pepsin) and microbial (e.g., Alcalase® and Neutrase®) sources. Although the use of plant proteases is still relatively limited to papain and bromelain from papaya and pineapple, respectively, the application of new plant proteases is increasing. This review presents the latest knowledge in the use and diversity of plant proteases for bioactive peptides release from food proteins including both available commercial plant proteases as well as new potential plant sources. Furthermore, the properties of peptides released by plant proteases and health benefits associated in the control of disorders such as hypertension, diabetes, obesity, and cancer are reviewed.     

Effect of acid treatment on extraction yield and gel strength of gelatin from whiptail stingray (Dasyatis brevis) skin

Food Science and Biotechnology - Chemical properties of fish gelatins differ from those of conventional mammalian sources, representing an attractive technological alternative for the food...     

Comparison of the milk-clotting properties of three plant extracts

Several proteases from plant sources have been proposed as milk coagulants, however, limited research has been done on their milk-clotting properties. The effect of temperature on the milk-clotting activity of kiwi fruit, melon and ginger extracts was evaluated, as well as the effects of the different extracts on curd properties. Melon extracts showed high milk-clotting activity over a broad temperature range (45–75 °C) while kiwi fruit and ginger extracts showed high activity over a narrower temperature range, with a maximum at 40 and 63 °C, respectively. Curds produced using kiwi extracts had textural properties comparable with those obtained using commercial rennet, while melon extracts produced a fragile gel and low curd yield. The milk-clotting behavior of the three plant extracts was related to the protease specificity present in these extracts. The kiwi proteases displayed chymosin-like properties and thus hold the best potential for use as a milk coagulant in cheese production.     

A Capillary Electrophoresis Method for the Determination of Hydroxyproline as a Collagen Content Index in Meat Products

The addition of collagen or its hydrolysates as a protein source or water binding agent is a common practice in the production of meat products. However, its level of addition is restricted by international regulations. Glycine, proline, and hydroxyproline are the most abundant amino acids in collagen, which is the main constituent of connective tissue. Thus, the objective of this study was to develop a method for the determination of hydroxyproline content in meat products by capillary electrophoresis (CE) as a collagen content index. Acid hydrolysis of samples and amino acid derivatization with fluorescamine prior to CE analysis were conducted. Separations were carried out using an uncoated capillary at 33 °C, using tetraborate buffer 0.05 M, pH 9.3 with 100 mM SDS. Hydroxyproline was detected at 214 nm. The assay was reproducible (RSD < 3% for normalized peak areas and migration times) and had good correlation (r = 0.975, p < 0.001) with the AOAC official method. From the samples tested (36), commercial ham showed the lowest average collagen content (<7.16 g per 100 g protein) by the CE method. On the other hand, frankfurter and Mexican “chorizo” sausages showed average collagen contents of 12.88 and 11.17 g per 100 g protein, respectively. The CE method developed could be used by regulatory agencies to ensure compliance with maximum levels of collagen addition in processed meats.     

Pacific whiting (Merluccius productus) underutilization in the Gulf of California: Muscle autolytic activity characterization

In México’s Northwest coast, Pacific whiting (Merluccius productus) is considered an under-utilized species because of its high tendency to become parasitized, thus promoting a high proteolytic activity present in muscle tissue. Sample fish for study were separated in lots by degree of parasitism in “apparent” parasitized (APP) and advanced parasitized (ADP). Thus, pH and temperature conditions of mayor endogenous proteolytic activity in muscle were determined. Maximum activity was detected at 50 °C (pH 3.5–4.0) and at 60 °C (pH 6.75–7.0). Parasitism degree had a significant effect in enzyme activity at acidic pH (p < 0.05) being higher in APP at low temperature (30 °C). Higher temperatures (40–50 °C) favored (p < 0.05) activity in ADP muscle (same pH range) with the highest (p < 0.05) observed at 50 °C at pH 3.5. No much difference was observed at pH 7.0–8.0. Results suggest that pH around physiological conditions at 60 °C could be used as an advantage in fish protein hydrolysate production or as processing aid where a protein hydrolysis is required.