Gelatin obtained from pig skin constitutes about 50% of world production and is mainly composed of collagen extracted from skin by acidic baths and thermal treatments. The gelatin is used to make ...various products, notably hard gelatin capsules (HGC) which of varying solubility in water. This issue has been known for many years and has been, and remains, a subject of study and debate. The main reason for low gelatin dissolution rates is its tendency to form cross-links in the denatured collagen chains under specific conditions which stabilize the gel network and prevent dissolution. As it is extracted from animal tissues, gelatin may contain molecules other than collagen (sugars, lipids and other proteins) which may react with collagen chains to form covalent bonds. Although this biopolymer has been the subject of numerous publications, its structure and composition is not well defined. Indeed, there are many differences from an article to another. Consequently, the causes of HGC dissolution are not well identified and controlled.
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•Gelatin cross-links reduce hard gelatin capsules dissolution in water.•Hydrophobic, hydrogen and electrostatic bonds contribute to aggregates in gelatin.•High molecular weights and aggregates in gelatin reduce its dissolution.
This paper deals with the extraction and emulsifying properties of proteins from Chlorella vulgaris. Solubilisation of proteins has been achieved using high pressure cell disrupter under pH=7 or ...pH=12. The higher solubilisation yield (52±3%w/w) was obtained using a combination of alkaline conditions and mechanical treatments (2.7kbar). After solubilisation, proteins were recovered by two procedures: precipitation in acid media and concentration/fractionation by tangential ultrafiltration. Proteins were analysed for their molecular weights, isoelectric points and amino acids compositions and their emulsifying properties were quantified and compared to those of commercial ingredients. In spite of lower yield, better emulsifying capacity was obtained when protein solubilisation takes place at pH=7 and when using proteins from permeate of tangential ultrafiltration. In all cases, emulsifying capacity (1780±20 and 3090±50mLoil/g protein) and stability (72±1% and 79±1%) of microalgae proteins remained comparable or higher than the commercial ingredients such as sodium caseinate.
A simple and reliable method for the determination of surface hydrophobicity of nonsolubilized myofibrils (from pig
M. longissimus dorsi) was developed and validated. This method is based on the ...interaction of the hydrophobic chromophore bromophenol blue (BPB) with myofibrillar proteins and the separation of free and bound BPB by centrifugation. The titration of bound BPB is performed by absorption spectroscopy, and the amount of bound BPB is considered as an index of protein hydrophobicity. Heating, which is known to increase protein hydrophobicity, was performed in order to validate this method. Fixation of BPB to myofibrils increased with heating time and temperature, strongly suggesting that it may be closely related to protein hydrophobicity.
The preservation of meat by methods such as salting, drying and/or smoking is ancestral and is linked to culinary heritage, through the geographical anchorage. These features and the associated ...know-how are the basis for the construction and recognition of quality signs that guarantee and certify certain commitments. Nevertheless, current scientific evidence shows that the consumption or particularly the over-consumption of certain meat products is conducive to the development of health problems. This raises the question of how to make these foods healthier without betraying their identity. This review addresses the possible levers.
Livestock generates high quantities of residues, which has become a major socioeconomic issue for the meat industry. This review focuses on the identification of bioactive peptides (BPs) in animal ...byproducts and meat wastes. Firstly, the main bioactivities that peptides can have will be described and the methods for their evaluation will be discussed. Secondly, the various origins of these BPs will be studied. Then, the techniques and tools for the generation of BPs will be detailed in order to discuss, in the final part, how peptides could be used and assimilated. BPs possess diverse biological activities and can be strategic candidates for substituting synthetic molecules. In silico potentiality studies are a helpful tool to understand and predict BPs released from proteins and their potential activities. However, in vitro validation is often required. Although BP use is compelled by strict regulations in relation to the field of application, they are also limited by their low bioavailability and bioaccessibility. Therefore, it is important to test peptide stability during gastrointestinal digestion. Protective strategies have been discussed since their use could improve the stability and effectiveness of BPs.
Huge amounts of animal by-products are generated along processing for human consumption. This material adds up to 50% of the animal weight, representing a serious economic and environmental concern.
...A shift to a molecular level of utilisation of those residues could be a viable and cost-effective option, where the biomolecules recovered would be applied outside the agricultural sector. In this regards, the structural fibrous proteins collagen, elastin and keratin, and respective hydrolysates and small peptides, can be recovered from fisheries, poultry and red meat slaughter residues and employed in high-priority fields such as food, biomedicine and pharmaceutics, and in highly profitable areas such as cosmetics. Bones (from fish and meat), skin (from pig and fish) and fish scales are a source of collagen; ligaments (from cattle, pig and poultry) are a source of elastin while keratin could be recovered from poultry feathers and pig hair. Beside the documented relevance of collagen, elastin and keratin in cosmetic and pharmaceutics, and of gelatine in the food and photographic industry, a number of new applications can look at them as promising ingredients.
The spontaneous self-assembly of the native α-helix of collagen, elastin and keratin allows conceiving biomaterials, emulsions, foams, stable colloids, as well as micro- and nanocapsules. Alongside this, the biological activities of small peptides, such as the antihypertensive, antimicrobial, antioxidant, wound-healing, osteogenic, haemostatic and chelating capacity, give the possibility to look at animal by-products as a remarkable source of functional compounds, whose application will contribute to the agro-food industry sustainability.
•Collagen, elastin and keratin can be recovered from animal by-products.•They are structural fibrous proteins showing broad functionality and bioactivity.•The whole or hydrolysed form can be applied according to specific purposes.•Bio-based application can be conceived.•The recovery could prompt innovation and better valorization of animal by-products.
•There is no nitrosamines in cooked ham up to 120 ppm of added nitrite.•In cooked ham, nitrite reduced lipid oxidation without additional ascorbate effect.•The second cooking generated nitrosamines ...regardless to the dose of added nitrite.•Ascorbate lowered the level of nitrosamines during the second cooking.
Nitrite, added to cured meat for its bacteriological and technological properties, is implicated in the formation of nitroso compounds (NOCs), such as nitrosylheme, nitrosamines and nitrosothiols, suspected to have a potential impact on human health. The mechanisms involved in NOC formation are studied in regard with the dose–response relationship of added nitrite and its interaction with ascorbate on NOC formation in a cured and cooked meat model. The impact of a second cooking stage on nitrosation was evaluated. The addition of nitrite in the cured and cooked model promoted heme iron nitrosylation and S-nitrosation but not N-nitrosation. Nitrite reduced lipid oxidation without an additional ascorbate effect. The second cooking sharply increased the nitrosamine content while the presence of ascorbate considerably lowered their levels and protected nitrosothiols from degradation. This study gives new insights on the chemical reactivity of NOCs in a cured meat model.
Effect of pasture- or concentrate-diet on myofibrillar protein oxidation and in vitro digestibility was measured in lamb meat (M.
longissimus dorsi) during a refrigerated storage of 7
days under gas ...permeable film. Protein oxidation was measured by the carbonyl content determined chemically using 2,4-dinitrophenylhydrazine (DNPH) and specific targets of oxidation were identified by immunoblotting. Carbonyl content significantly increased during storage and diet affected protein oxidation where animals fed concentrate showed higher carbonyl group levels than animals fed pasture. To evaluate effect of diet and storage time on protein digestibility, myofibrillar proteins were exposed to proteases of the digestive tract (pepsin, and a mixture of trypsin and α-chymotrypsin) in conditions of pH and temperature which mimic digestive process. The myofibrillar protein digestibility was not influenced by the diet. Storage time had no significant effect on myofibrillar protein susceptibility to pepsin while an important increase in digestibility by trypsin and α-chymotrypsin was detected during storage.
•Endogenous oxidative and nitrosative processes are interdependent.•Considerable protein carbonylation is observed in the digestive tract.•Ammonia oxidation contributes to endogenous nitrosamine ...formation.•Meat cooking and nitrite addition decrease protein digestion.
The chemical changes (oxidation/nitrosation) of meat proteins during digestion lead to a decrease in their nutritional value. Moreover, oxidized and nitrosated amino acids are suspected to promote various human pathologies. To investigate the mechanisms and the kinetics of these endogenous protein modifications, we used a dynamic artificial digestive system (DIDGI®) that mimics the physicochemical conditions of digestion. The combined effect of meat cooking and endogenous addition of ascorbate and nitrite was evaluated on protein oxidation (by measuring carbonyl groups), protein nitrosation (by measuring nitrosamines), and proteolysis. Considerable carbonylation was observed in the digestive tract, especially under the acidic conditions of the stomach. Nitrosamines, caused by ammonia oxidation, were formed in conditions in which no nitrite was added, although the addition of nitrite in the model significantly increased their levels. Meat cooking and nitrite addition significantly decreased protein digestion. The interactions between all the changes affecting the proteins are discussed.
Collagen antioxidant peptides are being widely studied. However, no research has paid attention to biological parameters such as the age and anatomy of collagen-rich tissues, which can determine a ...change in tissue structure and composition, and then in bioactivity. Moreover, only few research works have studied and assessed peptides antioxidant activity on the food matrix. This work aimed to investigate the effect of bovine's bone age and anatomy, and of six different enzymes, on the antioxidant activity of collagen peptides. Collagen was extracted from young and old bovine femur and tibia; six different enzymes were used for peptides' release. The redox potential, the quenching of stable free radicals, and the antioxidant capacity on bovine meat lipids and proteins was evaluated, under heating from ambient temperature to 80 °C. Age and anatomy showed a significant effect; the influence of anatomy becomes most important with age. Each enzyme's effectiveness toward age and anatomy was not the same. The greatest amount of peptides was released from young bones' collagen hydrolysed with papain. The antioxidant activity was higher at higher temperatures, except for meat proteins. Assessing the effect of age and anatomy of collagen-rich tissues can promote a better application of collagen bioactive peptides.
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