Processing technologies for improved digestibility of milk proteins

Enhancing the lipid stability of foods of animal origin using edible packaging systems

Foods of animal origin are prone to oxidation due to their high lipid content and fatty acid profile. Edible packaging systems have evolved as a new way of preserving animal-derived foods and have been reported to retard lipid oxidation using antioxidant molecules from side-streams, waste, and agricultural by-products. Studies have evaluated previously undocumented film materials and novel bioactive molecules as additives for edible packaging for animal-derived foods. However, none of the studies is specifically focused on evaluating the packaging systems available for enhancing lipid stability. This paper thoroughly examines and discusses the application of edible packaging containing novel antioxidant molecules for controlling the lipid oxidation of animal-derived foods. The paper analyses and interprets the main findings of the recently published research papers. The materials and active principles used for enhancing lipid stability have been summarised and the underlying mechanisms discussed in detail. Studies should aim at using cheaper and readily available natural ingredients in future for the production of affordable packaging systems.

Magnetic core-shell cellulose system for the oriented immobilization of a recombinant β-galactosidase with a protein tag

The objective of this study was to immobilize a recombinant β-galactosidase (Gal) tagged with a cellulose-binding domain (CBD) onto a magnetic core-shell (CS) cellulose system. After 30 min of reaction, 4 U/capsule were immobilized (CS@Gal), resulting in levels of yield and efficiency exceeding 80 %. The optimal temperature for β-galactosidase-CBD activity increased from 40 to 50 °C following oriented immobilization. The inhibitory effect of galactose decreased in the enzyme reactions catalyzed by CS@Gal, and Mg2+ increased the immobilized enzyme activity by 40 % in the magnetic CS cellulose system. The relative enzyme activity of the CS@Gal was 20 % higher than that of the soluble enzyme activity after 20 min at 50 °C. The CS support and CS@Gal capsules exhibited an average size of 8 ± 1 mm, with the structure of the shell (alginate-pectin-cellulose) enveloping and isolating the magnetic core. The immobilized β-galactosidase-CBD within the magnetic CS cellulose system retained ∼80 % of its capacity to hydrolyze lactose from skim milk after 10 reuse cycles. This study unveils a novel and promising support for the oriented immobilization of recombinant β-galactosidase using a magnetic CS system and a CBD tag. This support facilitates β-galactosidase reuse and efficient separation, consequently enhancing the catalytic properties of the enzyme.

Synthesis of γ-Cyclodextrin-Reduced Fe(III) Nanoparticles with Peroxidase-like Catalytic Activity for Bacteriostasis of Food

Foodborne pathogens are a primary cause of human foodborne illness, making it imperative to explore novel antibacterial strategies for their control. In this study, Fe-γ-CD was successfully synthesized as a food antibacterial agent for use in milk and orange juice. The Fe-γ-CD consists of 6/11 Fe(II) and 5/11 Fe(III), which catalyze a Fenton-like catalytic reaction with H2O2 to generate •OH. Consequently, Fe-γ-CD exhibits exceptional peroxidase-like activity and broad-spectrum antibacterial efficacy. Fe-γ-CD not only disrupts the wall structure of ESBL-E. coli but also induces protein leakage and genetic destruction, ultimately leading to its death. Furthermore, Fe-γ-CD inhibits biofilm formation by MRSA and eradicates mature biofilms, resulting in MRSA's demise. Importantly, Fe-γ-CD demonstrates negligible cytotoxicity toward normal mammalian cells, making it an ideal candidate for application as an antibacterial agent in foodstuffs. These findings highlight that Fe-γ-CD is an effective tool for combating the spread of foodborne pathogens and food safety.

Sustainable Process for Tortilla Production Using Ohmic Heating with Minimal Impact on the Nutritional Value, Protein, and Calcium Performance

The nixtamalization process used for tortilla production entails extended processing time and generates pollutant effluents. Ohmic heating (OH) is an emerging technology that uses an alternating electric current for rapid and uniform food heating and mitigates effluent concerns. However, gaps exist in nutrient bioavailability studies. In this work, we assessed OH's impact on tortilla nutritional value, protein, and calcium using a rat model. Twenty-five male Wistar rats were fed one of four diets for 21 days: raw corn (RC) as an experimental control, OH-processed tortillas (OHTs), traditionally processed tortillas (TPTs), commercial tortillas (CTs), and a casein diet (CD) as a growth control. Despite similar protein and macronutrient profiles, OH significantly enhanced insoluble fiber content. The weight gain sequence was OHTs > TPTs > CTs > RC. OHTs exhibited superior protein digestibility (88.52%), which was 3% higher than other diets. The serum albumin (2.63-2.73 g/dL) indicated moderate malnutrition due to the tortilla's lower protein content. Nonetheless, the protein efficiency ratio (1.2-1.74) showed no significant difference from TPTs. Bone characteristics and fracture strength resembled the tortilla-fed groups, surpassing RC. X-ray diffraction and scanning electron microscopy confirmed that the OHT and TPT diets improved male rat bone thickness and crystallinity. The findings suggest the potential for OH as an eco-friendly tortilla production method, maintaining nutritional value comparable to traditional methods.

Microwave treatment on structure and digestibility characteristics of Spirulina platensis protein

As a novel protein resource, the low digestibility of Spirulina platensis protein (SPP) limits its large-scale application. From the perspective of food processing methods, different heating treatments were explored to improve the structure and digestibility of SPP. In this study, SPP was heated by water bath and microwave at the same heating rate and heating temperature. Microwave accelerated protein denaturation and structure unfolded as the heating intensity increases, causing more exposed hydrophobic residues and enhancing surface hydrophobicity. The data of free sulfhydryl group, particle size, and gel electrophoresis, showed that microwave treatment promoted the formation of protein aggregates. The structural changes can potentially improve the accessibility of digestive enzymes, promote the in vitro digestibility rate, and further accelerate the production of small molecular peptides and the release of free amino acids. This study provided an innovative approach to improve the digestibility and therefore the utilization efficiency of SPP.

Locust protein hydrolysates have the potential to enhance the storage stability of cheese

The study evaluated the efficacy of locust protein hydrolysates (LoPHs) to enhance the quality of Cheddar cheese (ChCh) during storage. The locust protein (LoP) was pre-treated [microwave (Mic) or ultrasonication (Ult) or no treatment (Not)] before hydrolysis using alcalase enzyme (3% w/w). The ChCh samples containing LoPHs at the maximum level of 1.5% were evaluated for quality for 3 months (4 ± 1 °C) and subjected to gastrointestinal simulation. Both pre-treatments (Mic and Ult) significantly (P < 0.05) enhanced the antimicrobial and antioxidant activities of the LoPHs (Ult > Mic > Not). The ChCh samples with LoPHs exhibited significantly (P < 0.05) lower means for lipid oxidation (TBARS and free fatty acids), protein oxidation (total-carbonyl content) and microbial counts (psychrophilic, total plate and yeast/moulds) during the storage. A positive effect was found on the sensory quality of ChCh samples after one month of storage. The gastrointestinal simulation improved the antioxidant capacity of the stored ChCh samples. LoPHs can be used as a novel bio-preservative for cheese.

Understanding the factors affecting the surface chemical composition of dairy powders: a systematic review

Dairy powder, with abundant chemical components such as protein, fat, and lactose possessing diverse physical and chemical structures, can exhibit a surface composition distinct from its bulk content during the conversion of liquid milk into dry powder. Surface chemical composition is a significant parameter in the dairy industry, as it is directly associated with the techno-functional properties of dairy powder products. The current work provides an overview of the factors influencing the surface composition of dairy powders such as the bulk composition of raw milk (animal source and formulation), liquid dairy processing (homogenization, thermal treatment, and evaporation), the drying process (drying methods as well as operating conditions during the most commonly used spray drying), and storage conditions (temperature, relative humidity, and duration). The underlying mechanisms involved in the variations of particle surface composition include the mechanical properties of emulsion, milk fat globules redistribution caused by mechanical forces, adsorption competition and interactions of ingredients at the water/air interface, dehydration-induced alterations in particle structure, corresponding solid/solutes segregation differentiation during spray drying, and lactose crystallization-induced increase in surface fat during storage. Additionally, future research is suggested to explore the effects of emerging processing technologies on the surface composition modification of dairy powders.

Effect of Dietary Protein and Processing on Gut Microbiota—A Systematic Review

The effect of diet on the composition of gut microbiota and the consequent impact on disease risk have been of expanding interest. The present review focuses on current insights of changes associated with dietary protein-induced gut microbial populations and examines their potential roles in the metabolism, health, and disease of animals. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was used, and 29 highly relevant articles were obtained, which included 6 mouse studies, 7 pig studies, 15 rat studies, and 1 in vitro study. Analysis of these studies indicated that several factors, such as protein source, protein content, dietary composition (such as carbohydrate content), glycation of protein, processing factors, and protein oxidation, affect the digestibility and bioavailability of dietary proteins. These factors can influence protein fermentation, absorption, and functional properties in the gut and, consequently, impact the composition of gut microbiota and affect human health. While gut microbiota can release metabolites that can affect host physiology either positively or negatively, the selection of quality of protein and suitable food processing conditions are important to have a positive effect of dietary protein on gut microbiota and human health.