Infant formula (IF) requires further optimization as there are still differences in health consequences between human milk (HM) and IF.
The present review addresses the challenges and future ...opportunities inherent in the production of more biomimetic and sustainable IF. After presenting the targets, limitations and challenges for IF optimization, process innovations that could contribute to designing the next-generation of IF are discussed. The final section describes how such improvements should be addressed by means of a more systemic approach.
Gaps in our knowledge of the compounds and structures in HM and their effects on digestion and health still exist, rendering the biomimicry of HM more difficult. Overall, optimizing IF is complex and requires trade-offs between synergistic and conflicting objectives, which include HM biomimicry, safety, functionality, ingredient sourcing as well as environmental, economic and social sustainability issues. Process innovations and optimized technological routes, including minimal processing, offer opportunities to implement new ingredients and improve the preservation of IF compounds, while ensuring microbial safety and addressing several pillars of sustainability through energy costs or reductions in gas emissions. Given the complexity of producing biomimetic and sustainable IF, a multi-objective optimization strategy is proposed, reliant on a multidisciplinary approach, where nutrition and process engineering would play pivotal roles with assistance from other disciplinaries such as biochemistry, microbiology, pediatric medicine, data and consumer sciences and public health. This rethinking of IF production should be driven by a multidisciplinary, non-profit consortium involving the entire value chain.
•Lack of knowledge still exist regarding human milk compounds and structures.•Alternative processes open new avenue for infant formula (IF) optimization.•Multi-objective optimization will allow sustainable and biomimetic IF production.•Multi-disciplinary collaboration throughout the whole value chain is required.
Heat-induced protein gelled deposits, occurring during dairy processing, are industrially cleaned with caustic-based solutions. In order to develop general dissolution mechanisms of protein ...hydrogels, in analogy to general gelation mechanisms for globular proteins, different protein systems must be characterized. We report the first characterization of the dissolution behaviour of heat-set pure bovine serum albumin (BSA) hydrogels. At low alkali concentrations (<0.2 M NaOH), the formed BSA gels were dissolved as observed for whey protein mixtures or pure β-lactoglobulin gels. The key rate limiting step is suggested to be the destruction of inter-protein non-covalent interactions. At higher NaOH concentrations (>0.2 M) the dissolution rate of BSA gels was fairly constant, unlike seen before. Activation energy estimations of the rate yield very low value in certain conditions, again unlike seen before. It is suggested that mass transfer limitations occur during dissolution due to the large BSA size.
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•Pure BSA hydrogels are considered to develop general dissolution mechanisms.•BSA hydrogels dissolve at low alkali concentrations similar than β-lactoglobulin gels.•At high alkali concentration new behavior is observed, likely related to the large size of BSA.•Cleavage on non-covalent interactions is a key rate-limiting mechanism.
Propionibacterium freudenreichii is used as a cheese-ripening starter and as a probiotic. Its reported physiological effects at the gut level, including modulation of bifidobacteria, colon epithelial ...cell proliferation and apoptosis, and intestinal inflammation, rely on active metabolism in situ Survival and activity are thus key factors determining its efficacy, creating stress adaptation and tolerance bottlenecks for probiotic applications. Growth media and growth conditions determine tolerance acquisition. We investigated the possibility of using sweet whey, a dairy by-product, to sustain P. freudenreichii growth. It was used at different concentrations (dry matter) as a culture medium. Using hyperconcentrated sweet whey led to enhanced multistress tolerance acquisition, overexpression of key stress proteins, and accumulation of intracellular storage molecules and compatible solutes, as well as enhanced survival upon spray drying. A simplified process from growth to spray drying of propionibacteria was developed using sweet whey as a 2-in-1 medium to both culture P. freudenreichii and protect it from heat and osmotic injury without harvesting and washing steps. As spray drying is far cheaper and more energy efficient than freeze-drying, this work opens new perspectives for the sustainable development of new starter and probiotic preparations with enhanced robustness.
In this study, we demonstrate that sweet whey, a dairy industry by-product, not only allows the growth of probiotic dairy propionibacteria, but also triggers a multitolerance response through osmoadaptation and general stress response. We also show that propionibacteria accumulate compatible solutes under these culture conditions, which might account for the limited loss of viability after spray drying. This work opens new perspectives for more energy-efficient production of dairy starters and probiotics.
Spray drying is an established technique, which widely employs cylinder-on-cone type chambers. The air flow patterns inside such chambers are usually governed by transient fluctuations, which impact ...particle movement and drying history. To understand this impact, CFD using Lagrangian particle tracking through Eulerian flow-field was employed. The simulations revealed transient flow structures due to central jet deflections followed by rotating upwards sweep and formation of vortices. The self-sustained-fluctuations were intensified by high velocity of the main hot air inlet, while lower temperature thereof led to smoother fluctuations. Detailed numerical analyses on particles sampled at the outlet revealed that the distinct transient flow-field actually reduced the particle residence time compared to the residence time estimated via a simplified method ignoring flow-field fluctuations, while generating a wider distribution. No simple correlation was ascertained between the particle size and the residence time distributions, which indicates all sizes considered in the work are affected similarly by the air flow. These findings will benefit the designing of spray dryers.
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•Air flow pattern in a commercial scale spray dryer was analyzed via CFD technique.•Coherent transient flow structures due to central jet deflections were ascertained.•Flow field is governed by rotating upward sweep of deflected jet and vortex formation.•Transient flow field fluctuations reduce the overall particle residence time.•Residence time of all particle size classes is similarly affected by the air flow.
The market for dairy powders, including high added-value products (e.g., infant formulas, protein isolates) has increased continuously over the past decade. However, the processing and storage of ...whey protein isolate (WPI) powders can result in changes in their structural and functional properties. It is therefore of great importance to understand the mechanisms and to identify the structural markers involved in the aging of WPI powders to control their end use properties. This study was performed to determine the effects of different storage conditions on protein lactosylations, protein denaturation in WPI, and in parallel on their foaming and interfacial properties. Six storage conditions involving different temperatures (θ) and water activities (aw) were studied for periods of up to 12mo. The results showed that for θ≤20°C, foaming properties of powders did not significantly differ from nonaged whey protein isolates (reference), regardless of the aw. On the other hand, powders presented significant levels of denaturation/aggregation and protein modification involving first protein lactosylation and then degradation of Maillard reaction products, resulting in a higher browning index compared with the reference, starting from the early stage of storage at 60°C. These changes resulted in a higher foam density and a slightly better foam stability (whisking) at 6mo. At 40°C, powders showed transitional evolution. The findings of this study will make it possible to define maximum storage durations and to recommend optimal storage conditions in accordance with WPI powder end-use properties.
Propionibacterium freudenreichii is a beneficial bacterium used as a cheese starter and as a probiotic. Indeed, selected strains of P. freudenreichii combine both technological and health-promoting ...abilities. Moreover, during large-scale industrial production of dried bacteria and during consumption, P. freudenreichii may undergo different stressful processes. Osmotic adaptation was shown to enhance P. freudenreichii tolerance towards stresses, which are encountered during freeze-drying and during digestion. In this report, we compared the osmoadaptation molecular mechanisms of two P. freudenreichii strains. Both osmotolerance and osmoadaptation were strain-dependent and had different effects on multiple stress tolerance, depending on the presence of osmoprotectants. Availability of glycine betaine (GB) restored the growth of one of the two strains. In this strain, osmotic preadaptation enhanced heat, oxidative and acid stresses tolerance, as well as survival upon freeze-drying. However, addition of GB in the medium had deleterious effects on stress tolerance, while restoring optimal growth under hyperosmotic constraint. In the other strain, neither salt nor GB enhanced stress tolerance, which was constitutively low. Accordingly, whole cell proteomics revealed that mechanisms triggered by salt in the presence and in the absence of GB are different between strains. Osmotic adjustment may thus have deleterious effects on industrial abilities of P. freudenreichii.
Propionibacteria are found in various niches including fodder, silage, rumen, milk and cheeses. This means adaptation towards different ecological environments with different physicochemical parameters. Propionibacterium freudenreichii, in particular, is furthermore used both as dairy starter and as probiotic and is thus submitted to high scale industrial production. Production and subsequent stabilization still need optimization. Drying processes like freeze-drying are stressful. Osmotic adjustments may modulated tolerance towards drying. However, they are strain-dependent, medium-dependent and may either reduce or increase stress tolerance. A case-by-case study, for each strain-medium thus seems necessary. In this work, we identify key proteins involved in osmoadaptation and give new insights into adaptation mechanisms in P. freudenreichii. This opens new perspectives for the selections of strains and for the choice of the growth medium composition.
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•P. freudenreichii crossprotection by osmoadaptation is strain-dependent.•Glycine betaine is not necessarily beneficial for P. freudenreichii osmoadaptation.•Osmoadaptation increases P. freudenreichii CIRM-BIA 129 viability during freeze-drying.•P. freudenreichii CIRM-BIA 129 freeze-drying tolerance is higher following osmoadaptation in the absence of GB.
Understanding the mechanism of whey protein fouling along a plate heat exchanger is a challenging issue in the dairy industry. The influence of the calcium/protein molar ratio on β-lactoglobulin ...(β-LG) denaturation and its consequence both on fouling mass along the plate heat exchanger and the structure of the fouling layer were studied. The experimental design was defined by varying the calcium/protein molar ratio from 2.3 to 22.9 and fixing the total concentration of calcium at 100 ppm. Results established that both the β-LG denaturation rate constants and the distribution of fouling in the plate heat exchanger were strongly impacted by the calcium/protein molar ratio. Structural analysis provided evidence that the fouling layer evolved from a thin and dense structure at low calcium/protein molar ratio towards a thicker and more open structure at higher calcium/protein molar ratio.
The present study investigated the effect of flow conditions (temperature, agitators and stirring speed) on particle size reduction during the reconstitution process of milk powders. Images acquired ...with a granulomorphometer during reconstitution showed that the mixing system design had a strong influence on the course of the rehydration process. Laser light scattering data obtained for each temperature of reconstitution and agitator revealed that whatever the powder tested, the number of agitator revolutions required to achieve a given level of rehydration was constant and independent of the stirring speed. Kinetics of rehydration were shown to be much more sensitive to temperature than to stirring speed. Inversely, as expected, it was shown that granulation did not always improve rehydration time, depending on surface composition. This result revealed that both granulation/composition and flow should be considered in controlling the reconstitution process.
Spray drying is the gold standard for manufacturing dairy powders, due to its ability to maintain nutritional and functional properties and operate at high capacities. It is, however, extremely ...energy intensive, accounting for the largest share of total energy consumption in the powder manufacturing process. Therefore, spray dryer optimization, along with other water removal steps such as reverse osmosis and vacuum evaporation, is essential from a sustainability perspective. The objective of this paper is to review recent technological advances relating to product and process (reformulation, pretreatments and emerging technologies) which contribute to improved efficiency and reduced energy consumption in conventional spray drying based processes. Additionally, disruptive technologies that substantially reduce environmental footprint of powder manufacturing process by completely replacing spray drying are discussed.
Food‐related carbohydrates and proteins are often used as thermoprotectants for probiotic lactobacilli during industrial production and processing. However, the effect of inorganic salts is rarely ...reported. Magnesium is the second‐most abundant cation in bacteria, and commonly found in various foods. Mg2+ homeostasis is important in Salmonella and has been reported to play a critical role in their thermotolerance. However, the role of Mg2+ in thermotolerance of other bacteria, in particular probiotic bacteria, still remains a hypothesis. In this study, the effect of Mg2+ on thermotolerance of probiotic lactobacilli was investigated in three well‐documented probiotic strains, Lactobacillus rhamnosus GG, Lactobacillus casei Zhang and Lactobacillus plantarum P‐8, in comparison with Zn2+ and Na+. Concentrations of Mg2+ between 10 and 50 mmol l−1 were found to increase the bacterial survival upon heat challenge. Remarkably, Mg2+ addition at 20 mmol l−1 led to a 100‐fold higher survival of L. rhamnosus GG upon heat challenge. This preliminary study also showed that Mg2+ shortened the heat‐induced extended lag time of bacteria, which indicated the improvement in bacterial recovery from thermal injury.
Significance and Impact of the Study
In order to improve the productivity and stability of live probiotics, extensive investigations have been carried out to improve thermotolerance of probiotics. However, most of these studies focused on the effects of carbohydrates, proteins or amino acids. The roles of inorganic salts in various food materials, which have rarely been reported, should be considered when incorporating probiotics into these foods. In this study, Mg2+ was found to play a significant role in the thermotolerance of probiotic lactobacilli. A novel strategy may be available in the near future by employing magnesium salts as protective agents of probiotics during manufacturing process.
Significance and Impact of the Study: In order to improve the productivity and stability of live probiotics, extensive investigations have been carried out to improve thermotolerance of probiotics. However, most of these studies focused on the effects of carbohydrates, proteins or amino acids. The roles of inorganic salts in various food materials, which have rarely been reported, should be considered when incorporating probiotics into these foods. In this study, Mg2+ was found to play a significant role in the thermotolerance of probiotic lactobacilli. A novel strategy may be available in the near future by employing magnesium salts as protective agents of probiotics during manufacturing process.
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