Extraction of Sardine Myoglobin and Its Effect on Gelation Properties of Pacific Whiting Surimi

Comparative effects of four types of resistant starch on the techno-functional properties of low-fat meat emulsions

The behavior of resistant starch (RS) in meat matrix depends largely on its type. Hence, the comparative impacts of high amylose corn starch (RS2), retrograded starch (RS3), acetylated starch (RS4) and high amylose-lauric acid complex (RS5) on water-fat binding capacities, texture, color and microstructure of low-fat meat emulsions were investigated. Four types of RS improved water retention, emulsion stability, textural properties and brightness of low-fat meat emulsions, displaying even better potential than inulin (positive control). Compared with inulin, RS2 ∼ RS5 induced the transition from free water to immobilized water, increased storage modulus G' (by 21.90 %, 38.13 %, 55.73 % and 45.92 %, respectively), hydrophobic interactions (by 36.03 %, 60.84 %, 44.40 % and 48.04 %, respectively), disulfide bonds and β-sheet, which promoted the formation of tight protein gel networks. Notably, physical or chemical modified RS (RS3, RS4, RS5) displayed preferable and more similar water-fat binding properties, making them more promising for personalized application in low-fat functional meat products.

Unrinsed Nemipterus virgatus surimi provides more nutrients than rinsed surimi and helps recover immunosuppressed mice treated with cyclophosphamide

BACKGROUND

The rinsing process in the production of surimi can cause the loss of some important nutrients. To investigate the differences in nutritional properties between rinsed surimi (RS) and unrinsed surimi (US), this study compared the elemental composition, amino acid composition, fatty acid composition, proteomics, and an immunosuppression mouse model of surimi before and after rinsing, and analyzed the nutritional and immunological properties of RS and US.

RESULTS

The results showed that the protein, fat, and ash contents of RS were decreased compared with those of US; specifically, the contents of essential amino acids, semi-essential amino acids, non-essential amino acids, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids were decreased. In the non-labeled quantitative proteomics analysis, three high-abundance quantifiable protein contents and 68 low-abundance quantifiable protein contents were found in RS (P-values < 0.05, ratio > 2). Immune function experiments in mice revealed that both RS and US contributed to the recovery of immunity in immunocompromised mice. The effect of US was better than that of RS.

CONCLUSION

The rinsing process in surimi processing leads to the loss of nutrients in surimi. US promotes the recovery of immunity in immunocompromised mice more effectively than RS. © 2023 Society of Chemical Industry.

Physicochemical evaluation of sausages prepared by lantern fish (Benthosema pterotum) protein isolate

The purpose of this study was to show how sausages produced with lantern fish (Benthosema pterotum) protein isolate at two levels 4% (sample A) and 2% (sample B), and then, the physicochemical and sensory properties of sausages (A and B) were determined during the storage (14, 30, and 60 days) at 4°C. Firstly, fish protein isolate (FPI) prepared at alkaline pH (12). It was found that the acidic value, peroxide value (PV), and thiobarbituric acid (TBA) value of sausages increased during the storage. The highest level of TBA value was found at the second month of storage as 0.51 mg malonaldehyde/kg. The PV and acidic value reached to 9.45 meq/kg and 4.82 at the end of storage, respectively. Moreover, the stiffness, adherence, and springiness were assessed by texture profile analysis which was found sausages containing FPI had stronger texture and structure compared to control sample. The SDS-PAGE analysis identified the proteins from 15.4 to 202.3 kDa, which exhibit no major differences in protein patterns of two types of sausages. Furthermore, sensory evaluation diagnostic was carried out in terms of the sensory attributes such as texture, flavor, odor, color, and overall acceptability, and the results indicated the greatest overall acceptability in samples containing 2% FPI.

Development of Polyethylene Glycol and Hard Fat-Based Mucoadhesive Tablets Containing Various Types of Polyvinyl Alcohols as Mucoadhesive Polymers for Buccal Application

Topical drug application has the advantage of avoiding systemic side effects. We attempted to develop a long-acting matrix-type tablet containing indomethacin (IM) with low physical stimulus and potent mucoadhesive force to treat pain caused by oral aphtha. A mixture of polyethylene glycol (PEG) and hard fat was used as the tablet base. Ethylcellulose was added to the base in an attempt to control drug release. Tablets with PEG as a base were also prepared for comparison. Polyvinyl alcohols (PVAs) with various degrees of saponification were added to increase the mucoadhesive force. From the optical microscopic observations, formulations using PEG and hard fat exhibit PEG/hard fat dispersions caused by the stabilizing effects of PVA. Although the tablets using PEG and hard fat showed sufficient adhesiveness and sustained drug release, those using PEG as the base did not. Drug release was controlled by the amount of hard fat and the saponification degree of PVA. The drug release rate was most increased in a tablet containing PVA with an intermediate degree of saponification, PEG and hard fat. From differential scanning calorimetry and powder X-ray diffraction, IM was considered to exist in the molecular phase. From the results of buccal administration of tablets to rats, highest tissue concentrations were observed in the tablet containing PVA with the intermediate degree of saponification using PEG and hard fat, and the plasma concentrations were sufficiently low in comparison.

Effects of pH-treated Fish Sarcoplasmic Proteins on the Functional Properties of Chicken Myofibrillar Protein Gel Mediated by Microbial Transglutaminase

pH adjustment would be of advantage in improving the water holding capacity of muscle proteins. The objective of this study was to evaluate the addition of fish sarcoplasmic protein (SP) solution, which was adjusted to pH 3.0 or 12.0, neutralized to pH 7.0, and lyophilized to obtain the acid- and alkaline-treated SP samples, on the functional properties of the chicken myofibrillar protein induced by microbial transglutaminase (MTG). The solubility of alkaline-treated SP was higher than that of the acid counterpart; however, those values of the two pH-treated samples were lower than that of normal SP (p<0.05). All SP solutions were mixed with myofibrillar proteins (MP) extracted from chicken breast, and incubated with MTG. The shear stresses of MP with acid- and alkaline-treated SP were higher than that of normal SP. The thermal stability of MP mixture reduced upon adding SP, regardless of the pH treatment. The breaking force of MP gels with acid-treated SP increased more than those of alkaline-treated SP, while normal SP showed the highest value. The MP gel lightness increased, but cooking loss reduced, with the addition of SP. Smooth microstructure of the gel surface was observed. These results indicated that adjusting the pH of SP improved the water holding capacity of chicken myofibrillar proteins induced by MTG.

Interfacial viscoelasticity of myoglobin at air/water and air/solution interfaces: role of folding and clustering

This study describes the folding and organization of myoglobin (Mb) at the solution/air interface at different pH values of 2.5, 3.5, 5.5, 7.5, and 8.5. Dynamic surface tension and the associated dilational and shear viscoelasticity for Mb at these pH's have been studied using a sinusoidal surface compression and expansion for frequencies ranging from 0.01 to 0.4 Hz. The changes in dilational viscosity, elasticity, and fluorescence lifetime measurements have been related to the conformational changes of the protein films at the interface. It is observed that while acid-induced denaturation of the protein does not lead to large changes in dilational properties, the shear properties on the other hand are strongly influenced by it, and the protein behaves like a shear-thickening fluid. At higher pH, particularly at the isoelectric point, Mb is pseudoplastic indicating an increase in the shear viscosity. These results are strongly suggestive of formation of hydrophobic clusters at the protein-buffer interface because of the change in the overall charge distributions.

Structural changes and dynamic rheological properties of sarcoplasmic proteins subjected to pH-shift method

Structural changes and dynamic rheological properties of sarcoplasmic proteins from striped catfish ( Pangasius hypophthalmus ) treated by various pH-shift processes were investigated. Isoelectric precipitation of acid-extracted sarcoplasmic proteins led to the lowest solubility in water. Sarcoplasmic proteins were unfolded after extremely acidic and alkaline extraction, exposing tryptophan and aliphatic residues. The alpha-helical structure was converted to beta-sheet following acidic extraction, whereas alkaline treatment did not disturb the alpha-helical structure of sarcoplasmic proteins. Disulfide formation, hydrogen bonding via tyrosine residues, and hydrophobic interactions occurred under extreme pH extraction. Acidic extraction induced denaturation and aggregation of sarcoplasmic proteins to a greater extent than did alkaline treatment. Hydrophobic interactions via aliphatic and aromatic residues were formed during isoelectric precipitation. Sarcoplasmic proteins were partially refolded after isoelectric precipitation followed by neutralization. Sarcoplasmic proteins prepared from an alkaline pH-shift process readily aggregated to form a gel at 45.10 degrees C, whereas higher thermal denaturation temperatures (>80 degrees C) and gel points ( approximately 78 degrees C) were observed in acid-treated sarcoplasmic proteins. The pH condition used for extraction, precipitation, and neutralization greatly affected structural changes of sarcoplasmic proteins, leading to different thermal and dynamic rheological properties.