Modification of the structural and rheological properties of whey protein/gelatin mixtures through high pressure processing

Underused Marine Resources: Sudden Properties of Cod Skin Gelatin Gel

The main object of this work was to characterize the structure and properties of laboratory-made fish gelatin from cod skin in comparison with known commercial gelatins of fish and mammalian origin. This is one way we can contribute to the World Food Program and characterize foodstuff resources from alternative natural sources. Our research was based on the combination of an expanded set of complementary physical-chemical methods to study the similarities and distinctions of hydrogels from traditional and novel gelatin sources from underused marine resources. In this work, we have compared the morphology, supramolecular structure and colloid properties of two commercial (mammalian and fish) gelatins with gelatin we extracted from cold-water cod skin in laboratory conditions. The obtained results are novel, showing that our laboratory-produced fish gelatin is much closer to the mammalian one in terms of such parameters as thermal stability and strength of structural network under temperature alterations. Especially interesting are our experimental observations comparing both fish gelatins: it was shown that the laboratory-extracted cod gelatin is essentially more thermally stable compared to its commercial analogue, being even closer in its rheological properties to the mammalian one.

Effect of High-Pressure Processing on the Packaging Properties of Biopolymer-Based Films: A Review

Suitable packaging material in combination with high-pressure processing (HPP) can retain nutritional and organoleptic qualities besides extending the product’s shelf life of food products. However, the selection of appropriate packaging materials suitable for HPP is tremendously important because harsh environments like high pressure and high temperature during the processing can result in deviation in the visual and functional properties of the packaging materials. Traditionally, fossil-based plastic packaging is preferred for the HPP of food products, but these materials are of serious concern to the environment. Therefore, bio-based packaging systems are proposed to be a promising alternative to fossil-based plastic packaging. Some studies have scrutinized the impact of HPP on the functional properties of biopolymer-based packaging materials. This review summarizes the HPP application on biopolymer-based film-forming solutions and pre-formed biopolymer-based films. The impact of HPP on the key packaging properties such as structural, mechanical, thermal, and barrier properties in addition to the migration of additives from the packaging material into food products were systemically analyzed. HPP can be applied either to the film-forming solution or preformed packages. Structural, mechanical, hydrophobic, barrier, and thermal characteristics of the films are enhanced when the film-forming solution is exposed to HPP overcoming the shortcomings of the native biopolymers-based film. Also, biopolymer-based packaging mostly PLA based when exposed to HPP at low temperature showed no significant deviation in packaging properties indicating the suitability of their applications. HPP may induce the migration of packaging additives and thus should be thoroughly studied. Overall, HPP can be one way to enhance the properties of biopolymer-based films and can also be used for packaging food materials intended for HPP.

Recent application of protein hydrolysates in food texture modification

The demand for clean labels has increased the importance of natural texture modifying ingredients. Proteins are unique compounds that can impart unique textural and structural changes in food. However, lack of solubility and extensive aggregability of proteins have increased the demand for enzymatically hydrolyzed proteins, to impart functional and structural modifications to food products. The review elaborates the recent application of various proteins, protein hydrolysates, and their role in texture modification. The impact of protein hydrolysates interaction with other food macromolecules, the effect of pretreatments, and dependence of various protein functionalities on textural and structural modification of food products with controlled enzymatic hydrolysis are explained in detail. Many researchers have acknowledged the positive effect of enzymatically hydrolyzed proteins on texture modification over natural protein. With enzymatic hydrolysis, various textural properties including foaming, gelling, emulsifying, water holding capacity have been effectively improved. It is evident that each protein is unique and imparts exceptional structural changes to different food products. Thus, selection of protein requires a fundamental understanding of its structure-substrate property relation. For wider applicability in the industrial sector, more studies on interactions at the molecular level, dosage, functionality changes, and sensorial attributes of protein hydrolysates in food systems are required.

In silico-screened cationic dipeptides from scallop with synergistic gelation effect on ι-carrageenan

In this paper, some cationic dipeptides from scallop (Patinopecten yessoensis) male gonads (SMGs), which can synergistically gel with ι-carrageenan (ι-C), were screened by the in silico approach. Fourteen protein sequences of SMGs were obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and nano liquid chromatography-mass spectrometry/mass spectrometry (nanoLC-MS/MS) analysis and were then hydrolyzed via in silico simulation. A total of 414 sequences were obtained with 56 duplicates, half of which were positively charged at pH 7. Among the cation sequences, 171 had good water solubility, including two amino acids (Lys and Arg). The molecular weight analysis of the cationic water-soluble sequences showed that 0.2-0.3 kDa accounted for the highest proportion. Based on the obvious synergistic effect of Lys and ι-C, 11 Lys-containing dipeptides, including Ser-Lys (SK), Thr-Lys (TK), Trp-Lys (WK), Ala-Lys (AK), Leu-Lys (LK), Gly-Lys (GK), Val-Lys (VK), Cys-Lys (CK), Asn-Lys (NK), Phe-Lys (FK), and Met-Lys (MK), were finally screened out to study gelation with ι-C. It was found that the dipeptides/ι-C formed firm gels except WK/ι-C. The values of the storage modulus (G') of 11 dipeptides/ι-C were investigated by a rheometer. The G' of 8 dipeptides/ι-C was higher than 1000 Pa. These results indicated that the in silico-screened dipeptides from SMGs can form composite gels with ι-C, which can be used for the design and development of functional hydrogels.

Influence of natural colour blends of freeze-dried Gac aril and pulp on the quality of whey protein-mixed gelatin-based chewables

Gelatin gummy jelly is a chewable snack with attractive synthetic colour and flavour. The use of natural carotenoid colourant, found in Gac aril or pulp, potentially benefits consumer health. The objectives of this study were to formulate gummy prototypes designed with varying levels of gelatin, sucrose, and glucose syrup, to vary the addition of whey protein concentrate (WPC) and freeze-dried (FD) Gac aril and pulp to the selected prototype, and to investigate changes in coloured WPC-mixed gelatin gummy during storage. The prototype containing gelatin, sucrose, and glucose syrup at 10, 50, and 40%, respectively, was selected based on its hardness, gumminess, and chewiness values. The addition of WPC (0.75%) to the selected prototype increased the values of hardness, springiness, and gumminess but reduced the values of cohesiveness and chewiness. Coloured WPC-mixed gelatin gummy with blends (0.5 g/100 g) of FD Gac aril and pulp at a ratio of 75:25 appeared yellow-orange and received the highest acceptance score. The quality of coloured WPC-mixed gelatin changed to a dull colour and a softer texture gel during storage. Therefore, Gac-coloured WPC-mixed gelatin gummy improvement for colour and texture qualities should be of concern for shelf-life stability.

Advancement of food-derived mixed protein systems: Interactions, aggregations, and functional properties

Recently, interests in binary protein systems have been developed considerably ascribed to the sustainability, environment-friendly, rich in nutrition, low cost, and tunable mechanical properties of these systems. However, the molecular coalition is challenged by the complex mechanisms of interaction, aggregation, gelation, and emulsifying of the mixed system in which another protein is introduced. To overcome these fundamental difficulties and better modulate the structural and functional properties of binary systems, efforts have been steered to gain basic information regarding the underlying dynamics, theories, and physicochemical characteristics of mixed systems. Therefore, the present review provides an overview of the current studies on the behaviors of proteins in such systems and highlights shortcomings and future challenges when applied in scientific fields.

Thyme Antimicrobial Effect in Edible Films with High Pressure Thermally Treated Whey Protein Concentrate

Application of high pressure-thermal treatment (600 MPa and 70 °C, 20 min) for obtaining edible films functionalized with thyme extracts have been studied in order to evaluate the antimicrobial capacity of films structure to retain and release the bioactive compounds. The high pressure-thermally treated films (HPT) were compared with the thermally treated (TT) ones (80 ± 0.5 °C, 35 min). The film structures were analyzed and the sorption isotherms, water vapor permeability, antimicrobial activity and the volatile fingerprints by GC/MS were performed. The HPT film presented more binding sites for water chemi-sorption than TT films and displayed significantly lower WVP than TT films (p < 0.05). TT films displayed slightly, but significant higher, antimicrobial activity (p < 0.05) against Geotrichum candidum in the first day and against Bacillus subtilis in the 10th day of storage. The HPT film structure had ~1.5-fold higher capacity to retain volatiles after drying compared to TT films. From the HPT films higher amount of p-cymene and α-terpinene was volatilized during 10 days of storage at 25 °C, 50% RH while from the TT films higher amount of caryophyllene and carvacrol were released. During storage HPT films had a 2-fold lower capacity to retain monoterpenes compared to TT films.

Gelation of food protein-protein mixtures

Gelation of proteins is one of the principal means to give desirable texture to food products. Gelation of individual proteins in aqueous solution has been investigated intensively in the past, but in most food products the system contains mixtures of different types of proteins. Therefore one needs to consider interaction between different proteins both before and during gelation. Most food proteins can be classified as globular proteins, but casein and gelatin are also important food proteins. In this review the focus is on gelation induced by heating or cooling, which is the most commonly used method. After briefly discussing general features of protein aggregation and gelation, the literature on gelation of mixtures of different types of globular proteins is reviewed as well as that of mixtures of globular proteins with gelatin or with casein. The effect on the gel stiffness and the microstructure of the gelled mixtures will be discussed in terms of different scenarios that can be envisaged: independent aggregation and gelation, co-aggregation and phase separation.

Modeling counterion partition in composite gels of BSA with gelatin following high pressure treatment

We examine the morphology of hydrogels made of bovine serum albumin and gelatin following high pressure processing at 300 MPa for 15 min at 10 and 80 °C. Emphasis is on the distribution of added calcium counterions between the polymeric phases seen in changes in the structural properties of the composite gel. Protocol includes thermal and HPP treatments, dynamic oscillation rheology, ESEM, and modeling from the "synthetic polymer approach" to rationalize results. Pressurization at 10 °C produced continuous gelatin networks with dispersed BSA inclusions whereas pressurization at 80 °C yielded an inverse dispersion of BSA as the continuous phase supporting liquid gelatin inclusions. Lewis and Nielsen equations were adapted to predict the counterion distribution between the polymeric phases that profoundly affected the structural properties of the pressurized gels. The concept of counterion partition (p_c) is introduced to the literature to follow the phase behavior of the composites in the presence of added calcium counterions.