Impact of process and composition of formulas for elderly on in vitro digestion using the dynamic DIDGI® model.

Due to the lower efficiency of the elderly digestion system, new formulations are needed in order to increase the bioaccessibility of macronutrients. The aim of the work was to evaluate the effect of the process of protein sources production using either liquid (F2) vs spray dried milk proteins (F1/F3) and the source of lipids (vegetable oil (F1) vs mix of vegetable oil + bovine milk cream (F2/F3)) ingredients on the macronutrient digestion of three experimental elderly formulas. The dynamic in vitro digestion model DIDGI®, was adapted to simulate the digestive conditions of the elderly. An exhaustive review of the literature was carried out in order to simulate as closely as possible the elderly digestive parameters and constituted the starting point towards a consensus in vitro digestion model that will be proposed soon by the INFOGEST scientific network. The three experimental formulas (F1/F2/F3) differing by the composition and process applied were submitted to the DIDGI® dynamic in vitro digestion over four hours using parameters adapted to the elderly. The three formulas were compared in terms of proteolysis and lipolysis. A slight impact of the process (liquid vs spray-dried) on the degree of proteolysis at the end of digestion was observed with 50.8% for F2 compared to 56.8% for F1 and 52.9% for F3 with<5% of difference between the 3 formulas. Concerning the degree of lipolysis, the addition of bovine cream led to a lesser extent of lipolysis with 63.7 and 60.2% for F2 and F3 respectively versus 66.3% for F1 (containing only vegetable oil). Our results highlighted the beneficial input of the milk fat with a higher level of phospholipids and a lower ω6/ω3 PUFA ratio and can be a good alternative to the use of the vegetable fat in drinks for elderly people.

An Analytical Method to Quantify Osteopontin in Dairy Powders and Infant Formulas by Signature Peptide Quantification with UHPLC-MS/MS.

BACKGROUND: Osteopontin (OPN) is an important protein in human milk, and is of growing interest to infant formula (IF) manufacturers. OPN is present at low quantities in bovine milk and its derived ingredients, and there is a need for an accurate quantitative method in complex matrixes such as IF and growing-up milks (GUMs). OBJECTIVE: The objective of this work was to validate a method to quantify OPN in several dairy powders produced from bovine milk, including skimmed milk powder (SMP), whey protein concentrate (WPC), demineralized WPC and α-lactalbumin-enriched WPC (α-lac WPC). The method was further validated in intact-protein IF and GUM powders produced using combinations of these ingredients. METHODS: Test samples were digested using trypsin, and the most appropriate peptide fragmentation transitions were identified by UHPLC-MS/MS. Quantification was made against a standard curve constructed from OPN reference material, and isotopically-labelled peptide standards were used as internal standards. Curve linearity was assessed, and samples were spiked at two OPN levels. RESULTS: The validation parameters were met in almost all cases, with precision RSDr and RSDiR values ranging from 0.26-7.43% and 1.22-12.70%, respectively, and spike recoveries ranging from 88-102%. The method was used to accurately measure OPN in bovine milk-based IF and GUM powders with intact protein systems, based on comparisons with mass balance calculations. CONCLUSIONS: The results from this study show that the method is fit-for-purpose to support IF and GUM manufacturers in evaluating OPN contents of raw materials and products containing whole, intact protein systems from bovine milk. HIGHLIGHTS: An LC-MS/MS method was developed to measure OPN in dairy powders, IF and GUMs containing whole, intact protein systems from bovine milk.

Influence of calcium fortification on physicochemical properties of whey protein concentrate solutions enriched in α-lactalbumin.

In this study, three whey protein concentrate systems enriched in α-lactalbumin, produced using membrane filtration (LAC-M), selective precipitation (LAC-P) and ion-exchange chromatography (LAC-IE), were fortified with calcium chloride (CaCl2) at 0-5 mM and changes in physicochemical properties studied. Binding of calcium (Ca2+) occurred for LAC-P in the range 0.00-2.00 mM, with an affinity constant (Kd) of 1.63 × 10-7, resulting in a proportion of total protein-bound calcium of 81.8% at 2 mM CaCl2. At 5 mM CaCl2, LAC-P had volume mean diameter (VMD) of 638 nm, while LAC-M and LAC-IE had VMD of 204 and 3.87 nm, respectively. Changes in physicochemical properties were dependent on the approach used to enrich α-lactalbumin and concentrations of other macromolecules (e.g., phospholipid). The results obtained in this study provide fundamental insights into the influence of fortification with soluble calcium salts on the physicochemical stability of next-generation whey protein ingredients enriched in α-lactalbumin.

Analytical Method for Lactoferrin in Milk-Based Infant Formulas by Signature Peptide Quantification with Ultra-High Performance LC-Tandem Mass Spectrometry.

Background: There is a need for a standardized method for quantification of lactoferrin in infant formulas, and manufacturers have started fortifying lactoferrin to mimic the higher levels found in human milk. A variety of current methods exist, but specificity and accuracy are challenging with the infant formula matrix. The use of signature peptides and MS is becoming more prevalent in the realm of analytical chemistry for quantification of proteins. Objective: The objective of this work was to develop and validate a method through a single-laboratory validation for quantification of lactoferrin in milk-based infant formula and begin to lay the foundation for a standardized method. Methods: The method presented uses signature peptides to quantify lactoferrin in milk-based infant formulas by ultra-high performance LC-tandem mass spectrometry (MS/MS). These peptides are produced through tryptic digestion, and fragments produced from these peptides through MS/MS allow the specific quantification using correlating isotopically labeled peptides. Results: The validation parameters were all met with precision RSDr ranging from 2.1 to 7.1 and intermediate RSDR ranging from 7.0 to 10.4 across different fortified milk-based infant formulas. Accuracy with certified reference material resulted in mean recoveries of 91.7-96.4%. Conclusions: The results from this study demonstrate the method is fit for purpose to support manufacturing specifications and nutritional labeling requirements.