Chemical Lipophilization of Bovine α-Lactalbumin with Saturated Fatty Acyl Residues: Effect on Structure and Functional Properties

Abstract

Bovine α-lactalbumin (α-LA) was chemically modified by the covalent attachment of fatty acid residues of different length (lauroyl, palmitoyl, and stearoyl) to modify its functional and antioxidant properties. Structural changes, functional properties, and antioxidant capacity in the pH interval between 3 and 10 were analyzed. Surface properties were improved. The esterification increased the hydrophobic interactions leading to a reduction in the solubility dependent on the incorporation ratio of the fatty acid residues. Improvement in emulsifying, foaming, and antioxidant properties were observed when the length of the fatty acid chains was short and mostly at a basic pH. With these results in mind, experiments could be conducted for the technological applications of these derivatives in the food, pharmaceutical, and cosmetic industries.

Functional Properties of Rye Prolamin (Secalin) and Their Improvement by Protein Lipophilization through Capric Acid Covalent Binding

“…Such observed SI decrease could be primarily due to the increased hydrophobic features of acylated SCL related to the covalent incorporation of numerous fatty acid chains, determining a reduction in charged chemical groups and the consequent possible formation of additional hydrogen bonds. Similar results have been reported by Mendoza-Sanchez et al [8] for bovine α-lactalbumin acylation. However, the highest SI was observed at alkaline pH values, both for unmodified and lipophilized SCL.…”

“…Table 3 reports the most recent results to be compared with the present findings obtained with SCL. A water solubility decrease similar to that reported in the present study was obtained following lipophilization of α-lactalbumin with fatty acid chloride chains longer than CAC [8], even though SCL lipophilization by CAC was found to be more effective. The improvement in SCL emulsifying properties after lipophilization was comparable to the results of other studies so that EAI value observed with SCL acylated with low CAC amounts (2 mmol/g) was almost similar to those observed using both soy protein-7S acylated with caproic acid [39] and rapeseed proteins acylated with maleic anhydride [41].…”

“…Moreover, ESI values of lipophilized SCL were close to those reported for pea and wheat gluten proteins acylated using succinic anhydride [37,38] and higher than those reported for acylated soy protein-7S, whey protein microgels, and rapeseed proteins [39][40][41]. On the other hand, the foaming capacity improvement of lipophilized SCL was very impressive when compared to all other previous results, even though the stability of the produced foams was similar to that of α-lactalbumin lipophilized with either lauroyl, palmitoyl, or stearoyl chlorides [8] as well as to that of whey protein microgels acetylated by acetic anhydride [40]. Conversely, WAC values of lipophilized SCL, unlike the most reported acylated proteins, showed a decreasing trend, while the increase observed in OAC values was similar to that reported for almost all the other acylated proteins.…”

“…Furthermore, it is well known that protein secondary and tertiary structure may change following a chemical modification able to cause alterations in the surface exposure of their amino acids [7]. Therefore, an induced increase in protein hydrophobicity can enable its integration into lipid systems and, consequently, trigger new, as well as ameliorated or impaired, functional properties [6,8].…”

Esterified Soy Proteins with Enhanced Antibacterial Properties for the Stabilization of Nano-Emulsions under Acidic Conditions

“…Until recently, changing the protein pI by chemical modification has been considered an effective method to improve the solubility of protein near the original pI [ 6 , 7 , 8 ]. The esterification reaction has blocked the carboxyl groups of the protein, so that the net positive charge of the protein increases, along with the pI, thereby causing a higher solubility of the protein in a low-pH range.…”