Effects of Drying Methods on Serum Protein Powder Properties

This study investigated the effects of atmospheric spray drying (ASD), low-pressure spray drying (LPSD) and freeze drying (FD) on the properties of serum protein powder, including the basic characteristics of the powder, bioactive proteins and changes in protein profile, using a proteomics approach. The total solid and water activity of the powder obtained by FD was significantly higher than that obtained by ASD and LPSD. There was no significant difference in the content of fat, lactose or solubility between the three kinds of powders. The concentration and activity of the proteins/enzymes in the serum protein powder made from LPSD were not altered after drying, similar to FD, although both parameters decreased after ASD. The microstructure of the powder observed by scanning electron microscopy indicated that the powder manufactured by ASD and LPSD was spherical in structure, while that manufactured by FD was flake-like. In total, there were 245 proteins identified in the serum protein concentrate and powder from the three drying methods. These findings indicate that LPSD is an effective and cost-saving method for producing serum whey protein powder.

Glycoproteomic and Lipidomic Characterization of Industrially Produced Whey Protein Phospholipid Concentrate with Emphasis on Antimicrobial Xanthine Oxidase, Oxylipins and Small Milk Fat Globules

This work investigates the composition of whey protein phospholipid concentrate (WPPC), an underutilized dairy stream, and reveals that it is a source of many bioactive compounds that can benefit the immune system and gut health. Our glycoproteomics approach uncovered that proteins derived from the milk fat globule membrane (MFGM) represent 23% of the total protein relative abundance and identified 85 N-glycans. Released sialic acid, an additional marker of glycosylation, ranged from 1.2 to 2% of the total weight. Xanthine oxidase, a glycosylated marker of MFG bioactivity, was found in high abundance and displayed higher antimicrobial activity than bovine milk, despite its similar fat and solids content. An average MFG diameter of 2.64 ± 0.01 µm was found in liquid WPPC, compared to 4.78 ± 0.13 µm in bovine milk, which likely explains the unusually high presence of glycosylated membrane-bound proteins and phospholipids, whose total fatty acids accounted for 20% of the WPPC total fatty acid pool. Free and bound oxylipins (mainly derived from linoleic acid) were also identified, together with other less abundant anti-inflammatory lipid mediators derived from eicosapentaenoic acid and docosahexaenoic acid. Our study demonstrates that WPPC represents a promising starting material for bioactive compound extraction and a functional vehicle for the delivery of small MFGs.

Comparative study of two types of pre-extraction treatment (drying or non-drying) on physicochemical, structural and functional properties of extracted insect proteins from Tenebrio molitor larvae

Microwave drying (MD) or freeze drying (FD) was commonly used as a drying treatment prior to the extraction of edible insect proteins. However, some quality defects (e.g., lipid oxidation or protein denaturation) were probably occurred via the drying step. To this end, the effect of drying or non-drying treatments (ND) after slaughtering by liquid nitrogen freezing on the physicochemical characteristics, structural and functional properties of Tenebrio molitor larvae protein (TMP) was investigated. The results indicate that TMP extracted from the ND group showed higher essential/total amino acid content, total/free sulfhydryl content, surface hydrophobicity, solubility, water/oil holding capacities, and emulsifying/foaming properties than those extracted from the MD or FD groups (P < 0.05). Moreover, the ND group had minimal impact on the structural changes of TMP which was associated with protein denaturation. Therefore, it can be concluded that a non-drying strategy prior to TMP extraction can improve functional properties and retard protein denaturation, while also conserving energy.

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Tenebrio molitor larvae was firstly slaughtered by liquid nitrogen freezing.

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Frozen larvae were subjected to either drying or non-drying treatment.

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Tenebrio molitor larvae protein (TMP) was extracted from dried or non-dried group.

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TMP extracted from the non-dried group had optimum functional properties.

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TMP extracted from the non-dried group had least degree of protein denaturation.

Effect of Drying Techniques on the Physical, Functional, and Rheological Attributes of Isolated Sunflower Protein and Its Hydrolysate

The influence of freeze and convection (at 40 and 50 °C) drying on the physical, functional, and rheological attributes of sunflower protein (SP) and its hydrolysate (SPH) was investigated. Compared with convectively-dried samples, the lightness, turbidity, bulk density, and particle size values of the freeze-dried SP and SPH were substantially higher, but the browning index was lower (p < 0.05). Additionally, freeze-dried samples exhibited good solubility and foaming characteristics, whereas lower emulsion properties with the most pH values were observed. Furthermore, SPHs possessed higher solubility as well as foamability over SPs under varying pH values (2.0–10.0), whilst reduction in the emulsion activity index was clearly observed (p < 0.05). Convectively-dried powders exhibited greater viscosity and consistency coefficient; and significantly lower flow behavior index of dispersions, relative to the respective freeze-dried preparations, indicating that dehydration methods influenced the flow behavior of the investigated samples. From a molecular weight analysis, convectively-dried samples at various temperatures were characterized with high proportion of small-sized particles at ≤1 kDa fractions over the respective powders obtained by freeze drying. The observations made, thus, would benefit food processors and manufacturers in electing better dehydration technique based on the desired traits of SP and SPH powders for successful application in food product formulations.

Dairy Processing Affects the Gut Digestion and Microecology by Changing the Structure and Composition of Milk Fat Globules

Milk fat globules (MFGs) are the major source of energy for infants' dietary intake. In this study, the effects of changes in the structure and composition of MFG after dairy processing on lipolysis and immune regulation were investigated. Pasteurized MFG tends to form protein aggregates to prevent lipolysis. However, the aggregate is rich in neutrophil degranulation products, which are effective in killing pathogens. Homogenized MFG has the lowest hydrolysis rate due to the reconstituted anti-lipase barrier and exposed apolipoprotein. Simultaneously, the reconstituted barrier can compensate for the lack of the complement cascade. Spray-dried MFG had the highest hydrolysis rate attributable to the disrupted MFG barrier and the release of lipoprotein lipase and endothelial lipase. The immunomodulatory properties of spray-dried MFG proteins are mainly mediated by the toll-like receptor (TLR) signaling pathway. This research provides the improvement basis of dairy processing and functional infant formulas.

Investigation of alterations in phospholipids during the production chain of infant formulas via HILIC-QTOF-MS and multivariate data analysis

Phospholipids play a key role in infant nutrition and cognitive function. In this study, hydrophilic interaction liquid chromatography coupled to quadrupole time-of-flight mass spectrometry method was firstly developed to analyze the composition of phospholipids. Then we characterized and quantified phospholipids extracted from raw, pasteurized, homogenized, and spray-dried milk to investigate the effect of the technological process on the composition of the phospholipids. Results indicate that the composition of the phospholipids underwent minor changes after pasteurization, while the concentration of phospholipids was significantly affected by the spray-drying process, especially phosphatidylethanolamine and phosphatidylinositol. Multivariate data analysis further verified the results and indicated that phospholipids containing polyunsaturated fatty acids had undergone significant changes during the production chain, especially in spray-drying. This work reveals the changes of phospholipids composition during the production chain of infant formulas and serve as a reference for the subsequent optimization of infant formulas to meet nutritional need of infants.

Effects of drying techniques on the physicochemical, functional, thermal, structural and rheological properties of mung bean (Vigna radiata) protein isolate powder

Mung bean is an inexpensive yet sustainable protein source. Current work compared the effects of freeze (FD), spray (SD) and oven drying (OD), on mung bean protein isolate (MBPI) produced on pilot scale. All samples showed no dissociation of protein subunits and were thermally stable (T_d = 157.90-158.07 °C). According to morphological studies, FD formed a porous protein while SD and OD formed wrinkled and compact crystals, respectively. FD and SD formed elastic gels with better gelling capacity than OD (aggregated gel). FD showed exceptional protein solubility, water and oil absorption capacity (4.23 g/g and 8.38 g/g, respectively). SD demonstrated the smallest particle size, excellent emulsion activity index (29.21 m²/g) and stability (351.90 min) and the highest β-sheet amount (37.61%). FTIR spectra for all samples showed characteristic peaks which corresponded well to the secondary structure of legume proteins. Rheological analysis revealed that gelation temperature for all MBPI lied around 90 °C. Current work described the different final properties achieved for MBPI produced under different drying techniques that allowed tailoring for different food systems, whereby FD is ideal for meat extender, SD is suitable for meat emulsion while OD is suitable in general protein-based application.

Phospholipid Composition and Fat Globule Structure I: Comparison of Human Milk Fat from Different Gestational Ages, Lactation Stages, and Infant Formulas

We compared phospholipids (PLs), PL fatty acid (FA) composition, and milk fat globule size and structure in human milk (n = 120) from mothers of full-term and preterm infants during lactation (colostrum, transition, 1 mo, 2 mo, and 3 mo) and 8 brands of infant formulas. The absolute quantification of PLs was analyzed using ³¹P NMR spectroscopy. Sphingomyelin was the dominant PLs (35.01 ± 3.31%) in human milk, whereas phosphatidylcholine and phosphatidylethanolamine were the dominant PLs in infant formulas. The PL content in preterm milk increased during lactation, whereas that in term milk remained stable. Saturated FAs (mainly 16:0 and 18:0) were the most abundant (>60%) PL FA in both preterm and term milk and increased throughout lactation. The mean diameter of milk fat globules in infant formulas was much smaller than that found in human milk (200 nm vs 5.63 μm). Significant differences were observed between human milk and infant formulas with regard to PLs, suggesting that more research is needed to mimic the PL profile in infant formulas.

Milk fat globules and associated membranes: Colloidal properties and processing effects

The composition and physical-chemical properties of the milk fat globule membrane (MFGM) is a subject that has gained increased interest in the field of food colloids, mainly because the nutritional and technological value of the MFGM. In fact, related changes in integrity and structure during milk processing pose a huge challenge as far as efforts directed to isolate the components of the fat globule membrane. MFGM characteristics and potential utilization are subjects of dissension. Thus, the effects of processing and the colloidal interactions that exist with other milk constituents need to be better understood in order to exploit milk fat and MFGM, their functionality as colloids as well as those of their components. These are the main subjects of this review, which also reports on the results of recent inquiries into MFGM structure and colloidal behavior.