Semi-industrial production of a minimally processed infant formula powder using membrane filtration.

Infant formula (IF) is submitted to several heat treatments during production, which can lead to denaturation or aggregation of proteins and promote Maillard reaction. The objective of this study was to investigate innovative minimal processing routes for the production of first-age IF powder, thus ensuring microbial safety with minimal level of protein denaturation. Three nutritionally complete IF powders were produced at a semi-industrial scale based on ingredients obtained by fresh bovine milk microfiltration (0.8 and 0.1-µm pore size membranes). Low-temperature vacuum evaporation (50°C) and spray-drying (inlet and outlet temperatures of 160 and 70°C, respectively) were conducted to produce the T- formula with no additional heat treatment. The T+ formula was produced with a moderate heat treatment (75°C for 2 min) applied before spray-drying, whereas the T+++ formula received successive heat treatments (72°C for 30 s on the milk; 90°C for 2-3 s before evaporation; 85°C for 2 min before spray-drying), thus mimicking commercial powdered IF. Protein denaturation and Maillard reaction products were followed throughout the production steps and the physicochemical properties of the powders were characterized. The 3 IF powders presented satisfactory physical properties in terms of aw, free fat content, glass transition temperature, and solubility index, as well as satisfactory bacteriological quality with a total flora <103 cfu/g and an absence of pathogens when a high level of bacteriological quality of the ingredients was ensured. Protein denaturation occurred mostly during the heat treatments of T+ and T+++ and was limited during the spray-drying process. The IF powder produced without heat treatment (T-) presented a protein denaturation extent (6 ± 4%) significantly lower than that in T+++ (58 ± 0%), but not significantly different from that in T+ (10 ± 4%). Although T- tended to contain less Maillard reaction products than T+ and T+++, the Maillard reaction products did not significantly discriminate the infant formulas in the frame of this work. The present study demonstrated the feasibility of producing at a semi-industrial scale an infant formula being bacteriologically safe and containing a high content of native proteins. Application of a moderate heat treatment before spray-drying could further guarantee the microbiological quality of the IF powders while maintaining a low protein denaturation extent. This study opens up new avenues for the production of minimally processed IF powders.

Can dynamic in vitro digestion systems mimic the physiological reality?

During the last decade, there has been a growing interest in understanding the fate of food during digestion in the gastrointestinal tract in order to strengthen the possible effects of food on human health. Ideally, food digestion should be studied in vivo on humans but this is not always ethically and financially possible. Therefore simple static in vitro digestion models mimicking the gastrointestinal tract have been proposed as alternatives to in vivo experiments but these models are quite basic and hardly recreate the complexity of the digestive tract. In contrast, dynamic models that allow pH regulation, flow of the food and injection in real time of digestive enzymes in the different compartments of the gastrointestinal tract are more promising to accurately mimic the digestive process. Most of the systems developed so far have been compared for their performances to in vivo data obtained on animals and/or humans. The objective of this article is to review the validation towards in vivo data of some of the dynamic digestion systems currently available in order to determine what aspects of food digestion they are able to mimic. Eight dynamic digestion systems are presented as well as their validation towards in vivo data. Advantages and limits of each simulator is discussed. This is the result of a cooperative international effort made by some of the scientists involved in Infogest, an international network on food digestion.

A first step towards a consensus static in vitro model for simulating full-term infant digestion.

In vitro alternatives to clinical trials are used for studying human food digestion. For simulating infant digestion, only a few models, lacking physiological relevance, are available. Thanks to an extensive literature review of the in vivo infant digestive conditions, a gastrointestinal static in vitro model was developed for infants born at term and aged 28days. The model was applied to the digestion of a commercial infant formula. Kinetics of digestion, as well as the structural evolution, were compared with those obtained while submitting the same formula to the adult international consensus protocol of in vitro static digestion. The kinetics of proteolysis and lipolysis differed according to the physiological stage resulting mainly from the reduced level of enzymes and bile salts, as well as the higher gastric pH in the infant model. This in vitro static model of infant digestion is of interest for scientists, food or pharmaceutical manufacturers.

Correlation between in vitro and in vivo data on food digestion. What can we predict with static in vitro digestion models?

During the last decade, there has been a growing interest in understanding food's digestive fate in order to strengthen the possible effects of food on human health. Ideally, food digestion should be studied in vivo on humans but this is not always ethically and financially possible. Therefore, simple in vitro digestion models mimicking the gastrointestinal tract have been proposed as alternatives to in vivo experiments. Thus, it is no surprise that these models are increasingly used by the scientific community, although their various limitations to fully mirror the complexity of the digestive tract. Therefore, the objective of this article was to call upon the collective experiences of scientists involved in Infogest (an international network on food digestion) to review and reflect on the applications of in vitro digestion models, the parameters assessed in such studies and the physiological relevance of the data generated when compared to in vivo data. The authors provide a comprehensive review in vitro and in vivo digestion studies investigating the digestion of macronutrients (i.e., proteins, lipids, and carbohydrates) as well as studies of the bioaccessibility and bioavailability of micronutrients and phytochemicals. The main conclusion is that evidences show that despite the simplicity of in vitro models they are often very useful in predicting outcomes of the digestion in vivo. However, this has relies on the complexity of in vitro models and their tuning toward answering specific questions related to human digestion physiology, which leaves a vast room for future studies and improvements.

Associations between weight status and liking scores for sweet, salt and fat according to the gender in adults (The Nutrinet-Santé study).

BACKGROUND/OBJECTIVES: As taste preferences may be associated with obesity, the present study investigated whether obese subjects presented heightened liking for the sensations of sweet, salt and fat. SUBJECTS/METHODS: Liking scores were determined by a questionnaire including 83 items on liking for sweet or fatty foods, and the preferred extent of seasoning with salt, sweet or fat. Data from 46909 adults included in the French web-based observational cohort of the Nutrinet-Santé study were collected and weighted according to the national population census. Relationships between liking scores and body mass index (BMI) as categorical or linear explanatory variable were assessed separately by gender using covariance and linear regression analyses, adjusted for age, education level, living area, smoking and alcohol. RESULTS: Overall liking scores for salt and fat were linearly positively linked to BMI in men and women (P≤0.001) and were higher in obese than in normal-weight individuals. The score difference between BMI categories was greater in women for fat liking only. For sweet liking, results differed between gender and compounding factors. Liking for added sugar and sweet foods was positively linked to BMI in women unlike in men; liking for natural sweetness was negatively linked to BMI in both genders. CONCLUSIONS: This study demonstrates that the relationship between liking and BMI differs according to the gender in its magnitude for fat and in its nature for sweet, unlike that for salt. Liking for sweet and fat may be linked to overconsumption of the corresponding foods, especially in women. This warrants further investigation.

Endogenous proteins in the ileal digesta of adult humans given casein-, enzyme-hydrolyzed casein- or crystalline amino-acid-based diets in an acute feeding study.

BACKGROUND/OBJECTIVES: To ascertain if the form of dietary nitrogen (free amino acids (AA), small peptides, or intact protein) affects the endogenous nitrogen containing substances lost from the upper digestive tract of humans. SUBJECTS/METHODS: Digesta were collected via a naso-ileal tube from the terminal ileum of 16 adult humans in a single parallel study following an acute feeding regimen. Subjects were given an iso-nitrogenous and isocaloric test meal containing 150 g of casein (CAS) (n=6), enzyme-hydrolyzed casein (HCAS) (n=5) or crystalline AA (n=5) dissolved in 550 ml of water, as the sole sources of nitrogen. RESULTS: The mean concentrations and flows of total nitrogen, protein nitrogen, and soluble protein nitrogen passing the terminal ileum were significantly higher (P <0.01) for the CAS and HCAS test-meal groups compared to the AA meal group. Dietary CAS and HCAS had a considerable influence on digesta mucin concentrations and flows compared to free AA (+41%). Only 3-4% of the total nitrogen remained unidentified. CONCLUSIONS: The form of dietary nitrogen (protein, small peptides or free AA) had an acute effect upon the secretion or reabsorption of endogenous proteins in the small intestine of healthy humans, as evident from significant differences in both the quantity and composition of the proteins found in digesta at the end of the ileum.

Commercial Phaseolus vulgaris extract (starch stopper) increases ileal endogenous amino acid and crude protein losses in the growing rat.

The effect of a commercial Phaseolus vulgaris extract (PVE, starch stopper) on ileal and fecal endogenous protein losses was studied. Growing rats were fed for 14 days a protein-free diet containing PVE at a nutritional concentration of 0% (PF1), 0.4% (PF2), or 1.1% PVE (PF3) or 1.1% autoclaved PVE (PF4). An indigestible marker (TiO(2)) was included in each diet. Ileal endogenous amino acid (AA) losses were significantly higher (P < 0.05) in PF3 (20% higher than in PF1), except for Pro, Gly, Ala, and His. Endogenous ileal N losses were 22% higher in PF3 than in PF1. Endogenous fecal AA and N losses were all significantly higher (P < 0.05) in PF3. Starch digestibility ( approximately 100%), food intake (single daily meal, d10-23), and body weight loss were not significantly different among the groups. PVE, at 1.1% of the diet, not only was ineffective in reducing starch digestibility but also led to increased ileal endogenous N losses, possibly due to the antinutritional factors (trypsin inhibitor, lectin) present in the PVE.