A modelling study on milk lactose hydrolysis and β-galactosidase stability under sonication

Recent developments in ultrasound approach for preservation of animal origin foods

Ultrasound is a contemporary non-thermal technology that is currently being extensively evaluated for its potential to preserve highly perishable foods, while also contributing positively to the economy and environment. There has been a rise in the demand for food products that have undergone minimal processing or have been subjected to non-thermal techniques. Livestock-derived food products, such as meat, milk, eggs, and seafood, are widely recognized for their high nutritional value. These products are notably rich in proteins and quality fats, rendering them particularly vulnerable to oxidative and microbial spoilage. Ultrasound has exhibited significant antimicrobial properties, as well as the ability to deactivate enzymes and enhance mass transfer. The present review centers on the production and classification of ultrasound, as well as its recent implementation in the context of livestock-derived food products. The commercial applications, advantages, and limitations of the subject matter are also subject to scrutiny. The review indicated that ultrasound technology can be effectively utilized in food products derived from livestock, leading to favorable outcomes in terms of prolonging the shelf life of food while preserving its nutritional, functional, and sensory attributes. It is recommended that additional research be conducted to investigate the effects of ultrasound processing on nutrient bioavailability and extraction. The implementation of hurdle technology can effectively identify and mitigate the lower inactivation of certain microorganisms or vegetative cells.

Role of Enzymatic Reactions in Meat Processing and Use of Emerging Technologies for Process Intensification

Meat processing involves different transformations in the animal muscle after slaughtering, which results in changes in tenderness, aroma and colour, determining the quality of the final meat product. Enzymatic glycolysis, proteolysis and lipolysis play a key role in the conversion of muscle into meat. The accurate control of enzymatic reactions in meat muscle is complicated due to the numerous influential factors, as well as its low reaction rate. Moreover, exogenous enzymes are also used in the meat industry to produce restructured products (transglutaminase), to obtain bioactive peptides (peptides with antioxidant, antihypertensive and gastrointestinal activity) and to promote meat tenderization (papain, bromelain, ficin, zingibain, cucumisin and actinidin). Emerging technologies, such as ultrasound (US), pulsed electric fields (PEF), moderate electric fields (MEF), high-pressure processing (HPP) or supercritical CO₂ (SC-CO₂), have been used to intensify enzymatic reactions in different food applications. This review aims to provide an overview of the enzymatic reactions taking place during the processing of meat products, how they could be intensified by using emerging technologies and envisage potential applications.

Locking the Ultrasound-Induced Active Conformation of Metalloenzymes in Metal-Organic Frameworks

Enhancing the enzymatic activity inside metal-organic frameworks (MOFs) is a critical challenge in chemical technology and bio-technology, which, if addressed, will broaden their scope in energy, food, environmental, and pharmaceutical industries. Here, we report a simple yet versatile and effective strategy to optimize biocatalytic activity by using MOFs to rapidly "lock" the ultrasound (US)-activated but more fragile conformation of metalloenzymes. The results demonstrate that up to 5.3-fold and 9.3-fold biocatalytic activity enhancement of the free and MOF-immobilized enzymes could be achieved compared to those without US pretreatment, respectively. Using horseradish peroxidase as a model, molecular dynamics simulation demonstrates that the improved activity of the enzyme is driven by an opened gate conformation of the heme active site, which allows more efficient substrate binding to the enzyme. The intact heme active site is confirmed by solid-state UV-vis and electron paramagnetic resonance, while the US-induced enzyme conformation change is confirmed by circular dichroism spectroscopy and Fourier-transform infrared spectroscopy. In addition, the improved activity of the biocomposites does not compromise their stability upon heating or exposure to organic solvent and a digestion cocktail. This rapid locking and immobilization strategy of the US-induced active enzyme conformation in MOFs gives rise to new possibilities for the exploitation of highly efficient biocatalysts for diverse applications.

Process study of ceramic membrane-coupled mixed-cell fermentation for the production of adenine

In order to solve the problems of high complexity, many by-products, high pollution and difficult extraction of the existing adenine production process, in this study, ceramic membrane-coupled mixed cell fermentation was used to produce adenine while reducing the synthesis of by-products and simplifying the production process of adenine. Nucleoside hydrolase (encoded by the rihC gene) was used to produce adenine by coordinated fermentation with the adenosine-producing bacterium Bacillus Subtilis XGL. The adenosine hydrolase (AdHy)-expressing strain Escherichia coli BL21-AdHy was successfully employed and the highest activity of the crude enzyme solution was found by orthogonal experiments at 170 W power, 42% duty cycle, and 8 min of sonication. The highest AdHy activity was found after 18 h of induction incubation. E. coli BL21-AdHy was induced for 18 h and sonicated under the above ultrasonic conditions and the resulting crude enzyme solution was used for co-fermentation of the strain and enzyme. Moreover, 15% (v/v) of the AdHy crude enzyme solution was added to fermentation of B. subtilis XGL after 35 h. Finally, the whole fermentation system was dialyzed using coupled ceramic membranes for 45 and 75 h, followed by the addition of fresh medium. In contrast, the AdHy crude enzyme solution was added after 35, 65, and 90 h of B. subtilis fermentation, with three additions of 15, 15, and 10% of the B. subtilis XGL fermentation system. The process was validated in a 5 L fermenter and 14 ± 0.25 g/L of adenine was obtained, with no accumulation of adenosine and d-ribose as by-products. The enzymatic activity of the AdHy crude solution treated with ultrasound was greatly improved. It also reduced the cellular activity of E. coli BL21-AdHy and reduced effects on bacterial co-fermentation. Membrane-coupled dialysis solved the problem of decreased yield due to poor bacterial survival and decreased viability, and eliminated inhibition of the product synthesis pathway by adenosine. The batch addition of crude enzyme broth allowed the continuous conversion of adenosine to adenine. This production method provides the highest yield of biologically produced adenine reported to date, reduces the cost of adenine production, and has positive implications for the industrial production of adenine by fermentation. And it provides a reference for producing other high-value-added products made by fermentation.

Recent Advances in the Application of Enzyme Processing Assisted by Ultrasound in Agri-Foods: A Review

The intensification of processes is essential for the sustainability of the biorefinery concept. Enzyme catalysis assisted by ultrasound (US) may offer interesting opportunities in the agri-food sector because the cavitation effect provided by this technology has been shown to improve the efficiency of the biocatalysts. This review presents the recent advances in this field, focused on three main applications: ultrasound-assisted enzymatic extractions (UAEE), US hydrolysis reactions, and synthesis reactions assisted by US for the manufacturing of agri-food produce and ingredients, enabling the upgrading of agro-industrial waste. Some theoretical and experimental aspects of US that must be considered are also reviewed. Ultrasonic intensity (UI) is the main parameter affecting the catalytic activity of enzymes, but a lack of standardization for its quantification makes it unsuitable to properly compare results. Applications of enzyme catalysis assisted by US in agri-foods have been mostly concentrated in UAEE of bioactive compounds. In second place, US hydrolysis reactions have been applied for juice and beverage manufacturing, with some interesting applications for producing bioactive peptides. In last place, a few efforts have been performed regarding synthesis reactions, mainly through trans and esterification to produce structured lipids and sugar esters, while incipient applications for the synthesis of oligosaccharides show promising results. In most cases, US has improved the reaction yield, but much information is lacking on how different sonication conditions affect kinetic parameters. Future research should be performed under a multidisciplinary approach for better comprehension of a very complex phenomenon that occurs in very short time periods.

Optimization of Ultrasonic Cellulase-Assisted Extraction and Antioxidant Activity of Natural Polyphenols from Passion Fruit

In this paper, ultrasonic cellulase extraction (UCE) was applied to extract polyphenols from passion fruit. The extraction conditions for total phenol content (TPC) and antioxidant activity were optimized using response surface methodology (RSM) coupled with a Box-Behnken design (BBD). The results showed that the liquid-to-solid ratio (X₂) was the most significant single factor and had a positive effect on all responses. The ANOVA analysis indicated quadratic models fitted well as TPC with R² = 0.903, DPPH scavenging activity with R² = 0.979, and ABTS scavenging activity with R² = 0.981. The optimal extraction parameters of passion fruit were as follows: pH value of 5 at 30 °C for extraction temperature, 50:1 (w/v) liquid-to-solid ratio with extraction time for 47 min, the experimental values were found matched with those predicted. Infrared spectroscopy suggested that the extract contained the structure of polyphenols. Furthermore, three main polyphenols were identified and quantified by HPLC. The results showed the content of phenolic compounds and antioxidant activity of the optimized UCE were 1.5~2 times higher than that determined by the single extraction method and the Soxhlet extraction method, which indicates UCE is a competitive and effective extraction technique for natural passion fruit polyphenols.

Thermosonication parameter effects on physicochemical changes, microbial and enzymatic inactivation of fruit smoothie

With the aim of developing a fruit-based beverage in products which are severely damaged by heat, a high-intensity ultrasound treatment combined with moderate heat treatment (called thermosonication) was applied. A fruit smoothie (mango, jackfruit and rice milk) was thermosonicated applying a Box-Benhken model with amplitude (70, 77.5 or 85%), time (15, 20 or 25 min) and temperature (40, 47.5 or 55 °C) as independent variables. From the obtained samples, microbiological (aerobic mesophilic and Enterobacteriaceae), physicochemical (pH, soluble solids and cloud index) and enzymatic analysis (polyphenol oxidase and pectin methylesterase) were carried out. Aerobic mesophiles and Enterobacteria inactivation in thermosonicated samples were 4.55 Log CFU/mL and 3.85 Log CFU/mL, respectively in most of the treatments applied, being influenced by linear terms of amplitude and temperature (p < 0.001). The cloud index was influenced by time term (p < 0.0001); meanwhile, interaction of amplitude * temperature (p < 0.01) and quadratic of time presented significant effect (p < 0.001) on polyphenol oxidase activity. Further, amplitude term had a significant effect (p < 0.001) on the decrease on pectin methylesterase enzymatic activity. The optimal process condition was 77.5% amplitude, 20 min and 47.5 °C. Thermosonication probed to be effective to control both enzymatic activities in treatments with high amplitudes combined with moderated temperature treatments. Based on this, the use of thermosonication is a viable alternative for fruit-based beverage preservation, that may employ perishable regional natural products offering them an added value.

Immobilization of lipase Eversa Transform 2.0 on poly(urea-urethane) nanoparticles obtained using a biopolyol from enzymatic glycerolysis

In this work, the free lipase Eversa^® Transform 2.0 was used as a catalyst for enzymatic glycerolysis reaction in a solvent-free system. The product was evaluated by nuclear magnetic resonance (¹H NMR) and showed high conversion related to hydroxyl groups. In sequence, the product of the glycerolysis was used as stabilizer and biopolyol for the synthesis of poly(urea-urethane) nanoparticles (PUU NPs) aqueous dispersion by the miniemulsion polymerization technique, without the use of a further surfactant in the system. Reactions resulted in stable dispersions of PUU NPs with an average diameter of 190 nm. After, the formation of the PUU NPs in the presence of concentrated lipase Eversa^® Transform 2.0 was studied, aiming the lipase immobilization on the NP surface, and a stable enzymatic derivative with diameters around 231 nm was obtained. The hydrolytic enzymatic activity was determined using ρ-nitrophenyl palmitate (ρ-NPP) and the immobilization was confirmed by morphological analysis using transmission electron microscopy and fluorescence microscopy.

Impact of ultrasound on galactooligosaccharides and gluconic acid production throughout a multienzymatic system

Galactooligosaccharides (GOS), recognised prebiotic, can be industrially produced from lactose and commercial β-galactosidase (β-gal) from Kluyveromyces lactis. Residual lactose and glucose limit GOS applications. To handle this problem, a multienzymatic system, with β-gal and glucose oxidase (Gox), was proposed to reduce glucose content in reaction media through its oxidation to gluconic acid (GA). Besides, ultrasound (US) probe effect over the multienzymatic system to produce GOS and GA has been evaluated. A production around 40% of GOS was found in all treatments after the first hour of reaction. However, glucose consumption and GA production was significantly higher (P < 0.05) for sequential reaction assisted by US, obtaining the best production of GOS (49%) and GA (28%) after 2 h of reaction. The conformational and residual activity changes of enzymes under US conditions were also evaluated, Gox being positively affected whereas in β-gal hardly any change was found.

Ultrasound assisted intensification of enzyme activity and its properties: a mini-review

Over the last decade, ultrasound technique has emerged as the potential technology which shows large applications in food and biotechnology processes. Earlier, ultrasound has been employed as a method of enzyme inactivation but recently, it has been found that ultrasound does not inactivate all enzymes, particularly, under mild conditions. It has been shown that the use of ultrasonic treatment at appropriate frequencies and intensity levels can lead to enhanced enzyme activity due to favourable conformational changes in protein molecules without altering its structural integrity. The present review article gives an overview of influence of ultrasound irradiation parameters (intensity, duty cycle and frequency) and enzyme related factors (enzyme concentration, temperature and pH) on the catalytic activity of enzyme during ultrasound treatment. Also, it includes the effect of ultrasound on thermal kinetic parameters and Michaelis-Menten kinetic parameters (k_m and V_max) of enzymes. Further, in this review, the physical and chemical effects of ultrasound on enzyme have been correlated with thermodynamic parameters (enthalpy and entropy). Various techniques used for investigating the conformation changes in enzyme after sonication have been highlighted. At the end, different techniques of immobilization for ultrasound treated enzyme have been summarized.

Lactose hydrolysis by β-galactosidase enzyme: optimization using response surface methodology

In the present study, it was aimed to optimize the process of lactose hydrolysis using free and immobilized β-galactosidase to produce glucose and galactose. Response surface methodology (RSM) by central composite design (CCD) was employed to optimize the degree of hydrolysis by varying three parameters, temperature (15-45°C), solution pH (5-9) and β-galactosidase enzyme concentration (2-8mg/mL) for free mode of analysis and sodium alginate concentration (2-4%), calcium chloride concentration (3-6%) and enzyme concentration (2-8mg/mL) for immobilized process. Based on plots and variance analysis, the optimum operational conditions for maximizing lactose hydrolysis were found to be temperature (35.5°C), pH (6.7) and enzyme concentration (6.7mg/mL) in free mode and sodium alginate concentration (3%), calcium chloride concentration (5.9%) and enzyme concentration (5.2mg/mL) in immobilized mode.