Protein Crosslinks Influence Food Digestion

Enzymatic crosslinking is increasingly applied to confer specific properties to different proteins and, consequently, to food products of which they are components. Among the most investigated enzymes, transglutaminases (in particular the microbial isoform, mTG) and various oxidative biocatalysts are having special attention by food biotechnology researchers. mTG catalyzes isopeptide bond formation among protein molecules, leading to inter-molecular crosslinks and being able to produce both homo- and hetero-polymers. Its peculiar properties, such as the calcium independency, the broad substrate specificity, the stability over a wide range of temperatures and pH values, make such enzyme an effective tool to modify the characteristics of many protein-based foods

Hydrocolloid-Based Coatings are Effective at Reducing Acrylamide and Oil Content of French Fries

French fries are popular products worldwide. However, this product is a sufferable source of high acrylamide due to high temperature and low moisture. The main objective of this study was to evaluate the effect of grass pea flour (GPF), transglutaminase (TGase)-treated (GPF + TGase), chitosan (CH), and pectin (PEC) hydrocolloid coating solutions on the formation of acrylamide, water retention as well as on oil content. In addition, the Daily Intake (DI) and Margin of Exposure (MOE) were calculated to estimate variations in risk assessment by applying coating solutions before frying. Our results showed that the highest acrylamide content was detected in the control sample, reaching a value of 2089 µg kg−1 . Hydrocolloid coating solutions were demonstrated to be an effective way to reduce acrylamide formation, with the percentage of acrylamide reduction equal to 48% for PEC, >38% for CH, ≥37% for GPF + TGase, and >31% for GPF, respectively. We hypothesized that the coatings were able to increase the water retention and, thus reduce the Maillard reaction, which is responsible for acrylamide formation. In fact, the MOE value for coated French fries was increase, resulting in being closer to the safety level to avoid carcinogenic risk. Moreover, our coatings were effective in reducing oil uptake

Immobilization of two endoglucanases from different sources

Cellulases are a important family of hydrolytic enzymes which catalyze the bond of cellulose and other related cello-oligosaccharide derivates. Industrial applications require enzymes highly stable and economically viable in terms of reusability. These costs can be reduced by immobilizing the cellulases, offering a potential solution through enzyme recycling and easy recovery. The covalent immobilization of enzymes is reported here: one is commercial cellulase from Aspergillus niger and other one is recombinant enzyme, named CelStrep it because was isolated from a new cellulolytic strain, Streptomyces sp. G12,. The optimal pH for binding is 4.6 for both cellulases and the optimal enzyme concentrations are 1 mg/mL and 5 mg/mL respectively. The support for immobilization is a poliacrylic matrix. Experiments carried out in this work show positive results of enzyme immobilization in terms of efficiency and stability and confirm the economic and biotechnical advantages of enzyme immobilization for a wide range of industrial applications

Stabilization of Charged Polysaccharide Film Forming Solution by Sodium Chloride: Nanoparticle Z-Average and Zeta-Potential Monitoring

Different natural biopolymers are becoming the issue of an expanding number of studies reporting their potential applications in food, pharmaceutical and cosmetic technologies, as well as in tissues engineering . In this respect, the utilization of charged polysaccharides like chitosan (CH) or pectin (PEC) appears to be one of the most interesting way in manufacturing of biodegradable new materials

Functionality of Films from Nigella sativa Defatted Seed Cake Proteins Plasticized with Grape Juice: Use in Wrapping Sweet Cherries

The main aim of this work is to improve the functionality of Nigella sativa protein concentrate (NSPC) films by using grape juice (GJ). The film’s mechanical, antioxidant, and antimicrobial activities were evaluated. The obtained results showed, for the first time, that GJ at concentrations of 2%–10% (v/v) are able to act as plasticizer for the NSPC films with promising film properties. The results showed that the tensile strength and Young’s modulus of NSPC films were reduced significantly when the GJ increased. However, the NSPC films prepared with 6% GJ observed a higher elongation at break compared with other films. Moreover, the obtained films showed very interesting and promising results for their antioxidant and antimicrobial properties compared with the control films. The sweet cherries wrapped with NSPC film showed that the TSS (Brix) was significantly lower compared to the control, after 10 days of storage. However, the titratable acidity, pH value, and L* of all cherries, either wrapped or not, was not significantly different in all storage times. On the other hand, hue angle was significantly lower after 10 days of storage at −18 °C compared with control films. GJ has a multi-functional effect for protein-based films as plasticizer, antioxidant, and antimicrobial function

Structure and in vitro digestibility of grass pea (Lathyrus sativus L.) flour following transglutaminase treatment

The impact of transglutaminase (TG) modification on microstructure and in vitro protein and starch digestibility of grass pea flour was investigated. Results demonstrated that grass pea flour proteins act as effective substrate of TG. Microstructural results showed that the addition of TG produced a more compact structure likely due to TG-catalyzed heteropolymers. Nutritional properties such as slowly digestible starch and expected glycemic index values followed the order: grass pea flour incubated in the absence of TG>grass pea flour incubated in the presence of TG>raw flour. The TG-catalyzed heteropolymers were easily digested as demonstrated by in vitro oral and gastric digestion carried out under physiological conditions. Therefore, TG-modified grass pea flour can be considered as a new source of starch and proteins suitable for feeding a large spectrum of population

Swelling, mechanical and barrier properties of albedo-based films prepared in the presence of phaseolin crosslinked or not by transglutaminase

Edible films were obtained from Citrus paradisi grapefruit albedo homogenates and bean protein phaseolin modified or not by the enzyme transglutaminase. Swelling capability, barrier performance to water vapor, oxygen and carbon dioxide, and mechanical properties of such films were investigated. The addition of the protein, mostly in the presence of transglutaminase, provide films less swellable at pH values above 5 compared to films made by albedo homogenates only, whereas the action of the enzyme clearly improves mechanical properties producing more stretchable and elastic films. Moreover, transglutaminase-mediated cross-linking of phaseolin gives rise to films less permeable to carbon dioxide and able to offer a high barrier to water vapor. These findings suggest that albedo-phaseolin film prepared in the presence of transglutaminase can be a promising candidate to be used as food edible wrap

Impact of transglutaminase treatment on properties and in vitro digestibility of white bean (Phaseolus vulgaris L.) flour

Common beans (Phaseolus vulgaris L.) are rich in nutrients and have significant amounts of proteins and complex carbohydrates, besides to be rich in unsaturated fatty acids and dietary fibres. Consumption of beans could be improved by processing them into flour. In this study the effect of microbial transglutaminase (TG) on the structure, physical (colour parameters, moisture, water holding capacity), thermal properties and in vitro digestion of undehulled (WB) and manually dehulled (SB) flour samples from white common beans (P. vulgaris L.) was evaluated. Flour samples were incubated in the absence and presence of TG (WB/TG and SB/TG). We observed that the enzyme is able to catalyse the formation of polymers, suggesting that the proteins occurring in the bean flour act as TG substrates. Microstructure of samples was examined by Scanning Electron Microscopy (SEM), while thermal properties were studied by Differential Scanning Calorimetry. Microstructural results showed that the TG-treated samples possess a more compact structure, made of starch granules surrounded by proteins that, presumably, contain TG-catalysed polymers. Moreover, TG treatment had a major impact on colour, water holding capacity (WHC) and thermal properties. In particular, WB and SB samples presented a darker colour than WB/TG and SB/TG samples, while the latter showed reduced WHC that was only 30% and 37% of WB and SB samples, respectively. The transition enthalpy (ΔH) in the temperature range from 57 to 70 °C (WB, WB/TG) and from 60 to 68 °C (SB, SB/TG) followed the order: WB/TG > WB and SB/TG > WB, respectively. In vitro digestion experiments indicate that the presence of isopeptide bonds decreased the digestibility of TG-treated flour samples

Lignin/Carbohydrate Complex Isolated from Posidonia oceanica Sea Balls (Egagropili): Characterization and Antioxidant Reinforcement of Protein-Based Films

A lignin fraction (LF) was extracted from the sea balls of Posidonia oceanica (egagropili) and extensively dialyzed and characterized by FT-IR and NMR analyses. LF resulted water soluble and exhibited a brownish-to-black color with the highest absorbance in the range of 250-400 nm, attributed to the chromophore functional groups present in the phenylpropane-based polymer. LF high-performance size exclusion chromatography analysis showed a highly represented (98.77%) species of 34.75 kDa molecular weight with a polydispersity index of 1.10 and an intrinsic viscosity of 0.15. Quantitative analysis of carbohydrates indicated that they represented 28.3% of the dry weight of the untreated egagropili fibers and 72.5% of that of LF. In particular, eight different monosaccharides were detected (fucose, arabinose, rhamnose, galactose, glucose, xylose, glucosamine and glucuronic acid), glucuronic acid (46.6%) and rhamnose (29.6%) being the most present monosaccharides in the LF. Almost all the phenol content of LF (113.85 ± 5.87 mg gallic acid eq/g of extract) was water soluble, whereas around 22% of it consisted of flavonoids and only 10% of the flavonoids consisted of anthocyanins. Therefore, LF isolated from egagropili lignocellulosic material could be defined as a water-soluble lignin/carbohydrate complex (LCC) formed by a phenol polymeric chain covalently bound to hemicellulose fragments. LCC exhibited a remarkable antioxidant activity that remained quite stable during 6 months and could be easily incorporated into a protein-based film and released from the latter overtime. These findings suggest egagropili LCC as a suitable candidate as an antioxidant additive for the reinforcement of packaging of foods with high susceptibility to be deteriorated in aerobic conditions