Non-thermal Treatment Research Articles

Enhancing the shelf stability of fresh‐cut potatoes via chemical and nonthermal treatments

Fresh-cut foods have become highly popular as these commodities are convenient to manage with premium freshness and quality. However, the shelf life of fresh-cut potatoes is limited. The traditional practice consists of a set of operations including washing, peeling, slicing, chemical treatment, packing, and storage. Besides, various chemical or synthetic additives are being applied to tackle quality-related issues such as browning, textural degradation, microbial spoilage, and shelf-life stability. Nevertheless, the demand for natural additives and nonthermal preservation techniques has increased with growing concerns about the potential health risks of chemical additives. This review paper discusses the use of various synthetic and natural food additives alone or in combination with the emerging nonthermal technologies for enhancing the quality characteristics of fresh-cut potatoes. Overall, the nonthermal processing technologies including sonication, cold plasma, high-pressure processing, ultraviolet, and pulsed electric field would be promising treatments for the fresh-cut food industry compared with conventional approaches. Practical applications Fresh-cut potato is highly susceptible to microbial spoilage and undergoes rapid loss of quality due to high moisture content and rapid metabolic rate. Researchers are exploring alternative nonthermal processing technologies for producing shelf-stable food products using a clean label approach. This review covers some recent advances concerning the use of chemical compounds, including plant natural antimicrobials and antioxidants, as well as nonthermal technologies for the quality maintenance of fresh-cut potato. These technologies are known to be safe, cost-effective, and can be upscaled for use in existing processing lines of the food industry.

Retention of polyphenols and vitamin C in cranberrybush purée (Viburnum opulus) by means of non-thermal treatments

The effects of high pressure processing (HPP; 200–600 MPa for 5 or 15 min) and pulsed electric field (PEF; 3 kV/cm, 5–15 kJ/kg) treatment on physicochemical properties (conductivity, pH and total soluble solids content), bioactive compounds (vitamin C, total phenolic (TPC), total flavonoid (TFC), total anthocyanin (TAC) and chlorogenic acid contents), antioxidant capacities (DPPH and CUPRAC assays) and polyphenol oxidase (PPO) activity of cranberrybush purée were evaluated immediately after processing. The results were compared to an untreated purée. According to the results, conductivity increased significantly after PEF (15 kJ/kg) treatment. PEF and HPP treatments resulted in a better retention of bioactive compounds (increase in TPC in the range of ~4–11% and ~10–14% and TFC in the range of ~1–5% and ~6–8% after HPP and PEF, respectively) and antioxidant activity (as measured with CUPRAC method) compared to untreated sample. HPP reduced residual enzyme activity of PPO comparatively better than PEF.

Processing Flavoured Milk by Thermal and Non Thermal Methods

Background: Research for new alternatives in food processing and preservation has become a priority of food scientists, not only to provide better quality products, but also to satisfy the needs and preferences of the consumer and further to fulfill regulations regarding food safety and to offer new varieties in the food market. These new alternatives include the use of other preservation factors, as opposed to heat, that are able to inactivate microorganisms and enzymes and provide better stability to the product with only minor changes in the overall quality of the food. Non-thermal processes have gained importance in recent years due to the increasing demand for milk with a high nutritional value and fresh-like characteristics, representing a substitute to conventional thermal treatments.Methods: This study was aimed to compare and evaluate the effectiveness of thermal and non- thermal technologies in microbial inactivation and shelf life extension of flavored milks such as rose milk and chocolate milk. UV radiation and pulsed electric field (PEF) technology were selected for non-thermal treatment of flavoured milks. In the food laboratory, high voltage laboratory and UV treatment chamber the milk samples were analyzed for a week.Result: Our findings in thermal and non- thermal (UV and PEF) methods of flavored milk showed that compare to thermal treatment of flavored milk non- thermal methods are good for preservation of flavored milk. Among the three methods, PEF treatment had an excellent effect on preserving the shelf life compared to thermal pasteurisation and UV radiation.

Биоцидная эффективность нетермальной аргоновой плазмы атмосферного давления

Introduction. New methods of sterilization with non-thermal atmospheric pressure plasma remain an extremely relevant field of food science. The present research estimated the effect of non-thermal argon plasma on lactic acid bacteria obtained from walnuts.
 Study objects and method. The non-thermal argon plasma was generated by electrode discharge induced by a coaxial microwave plasmatron at atmospheric pressure. The discharge was generated in a special electrode construction. Its stability was achieved via low gas flow through the discharge gap. Argon consumption was 10 L/min. The study involved Lactobacillus plantarum and Lactobacillus mali in their natural association and vegetative form. Endo’s medium (Endo agar) was inoculated with lactobacilli. 100 μl of the suspension were added into a Petri dish with nutrient medium and carefully rubbed with a spreader. The plates with Endo agar inoculated with lactobacilli were placed under plasma radiation at a distance of 45 mm. The biocidal effect of plasma radiation was estimated by the diameter of the affected areas. After the plasma treatment, the Petri dishes were incubated in an incubator for 24–48 h at 37°C, after which the diameters of the affected areas were measured again.
 Results and discussion. The paper introduces experimental data on the effect of argon plasma on lactobacilli isolated from food. After treating the surface of inoculated Petri dishes with non-thermal plasma for five minutes, the diameter of the inhibition zone reached the diameter of a Petri dish (80 mm) and exceeded the diameter of the spark gap of the plasma generator (36 mm). The temperature on the surface of the nutrient medium during plasma treatment was within the optimal temperature for lactobacillus growth, i.e. 37.3 ± 0.6°C, which excluded thermal effects. Only a few colonies survived a five-minute treatment. After one-minute treatment, the number of survived colony-forming units was considerably higher. 
 Conclusion. Non-thermal argon plasma treatment proved effective in inhibiting the growth of gram-positive bacteria (Lactobacillus isolated from walnuts) on solid surfaces (agar plates). After five minutes of plasma treatment, the inactivated area (80 mm) exceeded the anode electrode cross section (36 mm) of the plasma generator.

Photobiomodulation: An Effective Approach to Enhance Proliferation and Differentiation of Adipose-Derived Stem Cells into Osteoblasts.

Osteoporosis is regarded as the most common chronic metabolic bone condition in humans. In osteoporosis, bone mesenchymal stem cells (MSCs) have reduced cellular function. Regenerative medicine using adipose-derived stem cell (ADSC) transplantation can promote the growth and strength of new bones, improve bone stability, and reduce the risk of fractures. Various methods have been attempted to differentiate ADSCs to functioning specialized cells for prospective clinical application. However, commonly used therapies have resulted in damage to the donor site and morbidity, immune reactions, carcinogenic generation, and postoperative difficulties. Photobiomodulation (PBM) improves ADSC differentiation and proliferation along with reducing clinical difficulties such as treatment failures to common drug therapies and late initiation of treatment. PBM is a noninvasive, nonthermal treatment that encourages cells to produce more energy and to undergo self-repair by using visible green and red and invisible near-infrared (NIR) radiation. The use of PBM for ADSC proliferation and differentiation has been widely studied with multiple outcomes observed due to laser fluence and wavelength dependence. In this article, the potential for differentiating ADSCs into osteoblasts and the various methods used, including biological induction, chemical induction, and PBM, will be addressed. Likewise, the optimal laser parameters that could improve the proliferation and differentiation of ADSC, translating into clinical success, will be commented on.

Effect of post‐discharge time of plasma‐treated water (PTW) on microbial inactivation and quality of fresh‐cut potatoes

The feasibility of applying plasma-treated water (PTW) to fresh-cut potatoes was evaluated in this study. The characteristics of PTW were measured in relation to post-discharge time and PTW was distinguished based on the concentrations of nitrate, nitrite, and hydrogen peroxide. Inactivation results showed that disinfection efficiency differed according to PTW treatments depending on post-discharge time and the target bacteria. Disinfection efficiency of PTW for E. coli was maintained for 1 hr, but was lower when PTW aged for 1 week was applied. Meanwhile, only a small reduction of food-borne bacteria was found after treatment with freshly made PTW. Negligible change was observed in the color, weight loss, hardness, and pH of sliced potatoes treated with different types of PTW. It is suggested that PTW treatment is a promising alternative for the preservation of fresh-cut potatoes and that it is effective for up to 1 hr after its creation. Practical applications Atmospheric plasma technology is an emerging non-thermal treatment that could be applied in the food industry. This study presents that PTW treatment reduce microorganisms in the surface of food without altering food quality. Moreover, the effect was maintained for at least 1 hr. This investigation may help in promoting the availability of PTW in the food washing industry.

Novel inactivation methods of Doenjang (fermented soybean paste) by high pressure and ohmic heating.

The changes of the total cell number in doenjang (Korean traditional fermented soybean paste) by conventional conduction heating, high pressure non-thermal treatment, and ohmic heating were compared. A total of (101-102) CFU/g cells were decreased by heating at (100-105)°C for 10min. The inactivation rate was improved when heated to a temperature higher than 110°C, but the taste, color of doenjang were severely changed. Inactivation by high pressure at (200-800) MPa was not achieved, because the total cell did not reach a reduction of 101CFU/g. The total bacterial counts of 103CFU/g were decreased during ohmic heating at 15V and 60Hz for 10min, and showed the most effective inactivation. Therefore, application of the ohmic heating in doenjang with high viscosity can kill target microorganisms related to quality deterioration, and rapid and uniform ohmic heating leads to reduction in sensory quality damage.

Physical and Chemical Methods for Reduction in Aflatoxin Content of Feed and Food

Aflatoxins (AFs) are among the most harmful fungal secondary metabolites imposing serious health risks on both household animals and humans. The more frequent occurrence of aflatoxins in the feed and food chain is clearly foreseeable as a consequence of the extreme weather conditions recorded most recently worldwide. Furthermore, production parameters, such as unadjusted variety use and improper cultural practices, can also increase the incidence of contamination. In current aflatoxin control measures, emphasis is put on prevention including a plethora of pre-harvest methods, introduced to control Aspergillus infestations and to avoid the deleterious effects of aflatoxins on public health. Nevertheless, the continuous evaluation and improvement of post-harvest methods to combat these hazardous secondary metabolites are also required. Already in-use and emerging physical methods, such as pulsed electric fields and other nonthermal treatments as well as interventions with chemical agents such as acids, enzymes, gases, and absorbents in animal husbandry have been demonstrated as effective in reducing mycotoxins in feed and food. Although most of them have no disadvantageous effect either on nutritional properties or food safety, further research is needed to ensure the expected efficacy. Nevertheless, we can envisage the rapid spread of these easy-to-use, cost-effective, and safe post-harvest tools during storage and food processing.

Non-Thermal Intervention of Lung Tumor by Core-Shell Magnetic Nanoparticles in a Magnetic Field

K-Ras mutations result in normal cells dividing uncontrollably and becoming cancerous. The prognosis is currently poor for patients due to the lack of drugs that can effectively target these mutations. In this study, magnetic nanoparticles (MNPs) were prepared, characterized, and cooperated with a magnetic field to intervene in the growth of lung tumor cells. The rise in temperature of a stimulation coil was studied by numerical calculation. The non-thermal effects of MNPs under a magnetic force were analyzed. The cell experiments showed that the growth of A549 tumor cells slowed down. The result of a wound-healing assay also indicated that the migration of tumor cells was suppressed. Compared with magnetic stimulation without MNPs, MNPs enhanced the inhibitory effects of a magnetic field. This study suggests a new way to treat K-Ras driven lung tumors using non-thermal effects of MNPs without the side effects caused by thermal effects.

Role of non-thermal treatments and fermentation with probiotic Lactobacillus plantarum on in vitro bioaccessibility of bioactives from vegetable juice.

Lactic acid fermentation is a natural way to increase the bioactive and functional properties of fruit and vegetable juices. In this study, the in vitro gastrointestional digestion of phenolics, flavonoids, anthocyanins, and antioxidant activity of mixed vegetable juice was investigated as affected by fermentation with probiotic Lactobacillus plantarum and non-thermal treatments (ultraviolet (UV) and/or ultrasonic (US) treatment). For this purpose heat, US, UV or US/UV treated vegetable juice samples were fermented by probiotic L. plantarum and percentage recovery of bioactive (total phenolic (TPC), total flavonoid (TFC) and total anthocyanin contents (TAC) and antioxidant (DPPH [1,1-diphenyl-2-picrylhydrazyl] and CUPRAC [CUPric Reducing Antioxidant Capacity]) properties was evaluated during simulated gastrointestinal digestion. Total mesophilic aerobic bacteria (TMAB) and total yeast-mold (TYM) counts were significantly decreased by thermal and non-thermal processes and coliforms were fully eliminated. The bioaccessibility of total phenolics, anthocyanins, and flavonoids decreased after in vitro digestion. In general, recovery (5.78-34.71%) and serum availability of the bioactives was positively influenced by the fermentation and non-thermal treatments. Phenolics and anthocyanins exhibited the highest and the lowest recovery, respectively, while post-digestion recovery of antioxidant was between that of the phenolics and anthocyanins. This study confirmed that US and UV treatment could be advantageous alternatives to heat treatment for ensuring the microbial safety of vegetable juices with increased in vitro bioaccessibility of bioactive compounds while probiotic fermentation with L. plantarum contributed to the improvement of the bioactive profile. © 2021 Society of Chemical Industry.

Comparative assessment of HTST, hydrodynamic cavitation and ultrasonication on physico-chemical properties, microstructure, microbial and enzyme inactivation of raw milk

The effects of high-temperature short time (HTST), ultrasonication (US) and hydrodynamic cavitation (HC) on physicochemical properties, alkaline phosphatase (ALP) activity, microorganism, degree of protein hydrolysis (DPH), color, microstructure and overall particle size of raw milk were studied. The separation index (SI) was also measured during storage of treated milk at 4 ± 2 °C for 12 days. US was carried out at different intensities (200, 300, and 400 W) and time (4, 6, and 8 min) and HC at 4, 6, 8, and 10 psi for 5, 10 and 15 min. It was observed that HC showed 21% energy efficiency (η) with higher cavitational yield than US which had η <10%. Microbial log reduction of 2.30 ± 0.17 TPC and 2.26 ± 0.17 (YM) was obtained by HTST treatment. And about 0.9 and 0.7 microbial log reduction were observed in HC and US treatment respectively. Initially in non-thermal treatment, ALP activity increases slightly by 1–2% at 4 psi (HC) and 200 W (US), but with further increase in time and intensity, ALP activity decreases. In addition to that, there was an increase in the DPH from 0.716 ± 0.09% to about 3.608 ± 0.52 and 3.77 ± 0.15% in US and HC treated samples respectively. Also, with an increase in time and intensity, number of fat globules increased with a decreased diameter and overall particle size. In non-thermal treatment, except for samples treated at 200 W (US) and 4 psi (HC), no separation was observed during the storage which could be due to reduced size of fat globules (from 6.3 μm to 3–2.2 μm).

Retaining bioactive proteins and extending shelf life of skim milk by microfiltration combined with Ultraviolet-C treatment

The objective of this study was to evaluate the effectiveness of microfiltration (MF) of skim milk, alone or combined with ultraviolet-C (UVC) treatment, in extending the shelf life and retaining the native bioactive milk serum proteins, compared with high-temperature short-time (HTST) pasteurization. The vegetative bacterial load was reduced by ~3.5 log when applying M alone, by ~5 log when combining MF with UVC, while it was reduced by only ~2 log when applying HTST pasteurization. MF with UVC resulted in near complete elimination of vegetative bacteria, including coliforms. The refrigerated shelf life of skim milk was extended with increasing UVC dosage, as least for 40 days after MF combined with a UVC dosage at 39.3 mJ/cm2. An increasing UVC dosage would further reduce the bacterial load without obvious damage of bioactive milk serum proteins, such as lactoferrin, immunoglobulins, and lactoperoxidase. An LC-MS/MS based proteomics study also showed that HTST reduced the abundance of several native low-abundant milk serum proteins significantly, while MF, alone or in combination with UVC, did not change the proteome, even with higher UVC dosages. The results of this study can be used to facilitate the development of non-thermal treatments, and combinations therefore, for improving milk quality.

Mass Transfer During Osmotic Dehydration of Fruits and Vegetables: Process Factors and Non-Thermal Methods

Osmotic dehydration of fruits and vegetables is a slow process due to resistance in mass transfer (MT). This resistance can be modified by varying the osmotic solution or process conditions, or by employing non-thermal treatments (NTT). Some NTT modify the tissue structure by formation of pores in the cell membrane (such as pulse electric fields) or microchannels (such as ultrasound and osmosonication), and others increase the contact surface area with the tissue through a decrease in atmospheric pressure (such as vacuum pulses) or an increase of the system pressure (such as high hydrostatic pressures). Changes in the rate of MT caused by modifications in experimental conditions can be described with mathematical models, such as Fick’s second law. The aims of this review are to analyze the different factors that modify MT rate during osmotic dehydration, examine the application of NTT to modify MT, and to study models that describe these processes.

Plasma-Activated Water (PAW) as a Disinfection Technology for Bacterial Inactivation with a Focus on Fruit and Vegetables.

Plasma-activated water (PAW) is generated by treating water with cold atmospheric plasma (CAP) using controllable parameters, such as plasma-forming voltage, carrier gas, temperature, pulses, or frequency as required. PAW is reported to have lower pH, higher conductivity, and higher oxygen reduction potential when compared with untreated water due to the presence of reactive species. PAW has received significant attention from researchers over the last decade due to its non-thermal and non-toxic mode of action especially for bacterial inactivation. The objective of the current review is to develop a summary of the effect of PAW on bacterial strains in foods as well as model systems such as buffers, with a specific focus on fruit and vegetables. The review elaborated the properties of PAW, the effect of various treatment parameters on its efficiency in bacterial inactivation along with its usage as a standalone technology as well as a hurdle approach with mild thermal treatments. A section highlighting different models that can be employed to generate PAW alongside a direct comparison of the PAW characteristics on the inactivation potential and the existing research gaps are also included. The mechanism of action of PAW on the bacterial cells and any reported effects on the sensory qualities and shelf life of food has been evaluated. Based on the literature, it can be concluded that PAW offers a significant potential as a non-chemical and non-thermal intervention for bacterial inactivation, especially on food. However, the applicability and usage of PAW depend on the effect of environmental and bacterial strain-based conditions and cost-effectiveness.

Stress Resistance and Pathogenicity of Nonthermal-Plasma-Induced Viable-but-Nonculturable Staphylococcus aureus through Energy Suppression, Oxidative Stress Defense, and Immune-Escape Mechanisms

The occurrence of viable-but-nonculturable (VBNC) bacteria poses a potential risk to food safety due to failure in conventional colony detection. In this study, induction of VBNC Staphylococcus aureus was conducted by exposure to an atmospheric-pressure air dielectric barrier discharge-nonthermal-plasma (DBD-NTP) treatment with an applied energy of 8.1 kJ. The stress resistance profiles and pathogenicity of VBNC S. aureus were further evaluated. We found that VBNC S. aureus showed levels of tolerance of heat, acid, and osmosis challenges comparable to those shown by culturable S. aureus, while VBNC S. aureus exhibited enhanced resistance to oxidative and antibiotic stress, relating to the mechanisms of cellular energy depletion, antioxidant response initiation, and multidrug efflux pump upregulation. Regarding pathogenicity, NTP-induced VBNC S. aureus retained the capacity to infect the HeLa host cells. Compared with the culturable counterparts, VBNC S. aureus caused reduced immune responses (Toll-like receptor [TLR], nucleotide-binding oligomerization domain [NOD]) in HeLa cells, which was attributed to suppression of biosynthesis of the recognized surface ligands (e.g., peptidoglycan). Additionally, the proteomic analysis revealed that upregulation of several virulence factors (ClfB, SdrD, SCIN, SasH, etc.) could ensure that VBNC S. aureus would adhere to and internalize into host cells and avoid the host attack. The camouflaged mechanisms described above led to VBNC S. aureus causing less damage to the host cells, and their activity might result in longer intracellular persistence, posing potential risks during NTP processing.IMPORTANCE The consumer demand for freshness and nutrition has accelerated the development of mild decontamination technologies. The incomplete killing of nonthermal (NT) treatments might induce pathogens to enter into a viable-but-nonculturable (VBNC) status as a survival strategy. The use of nonthermal plasma (NTP) as a novel food decontamination technology received increased attention in food industry during recent decades. Our previous work confirmed that the foodborne pathogen S. aureus was induced into VBNC status in response to NTP exposure. This work further revealed the development of stress resistance and virulence retention of NTP-induced VBNC S. aureus through the mechanisms of energy suppression, oxidative stress defense, and immune escape. The data provide fundamental knowledge of the potential risks posed by NTP-induced VBNC S. aureus, which require further parameter optimization of the NTP process or combination with other techniques to avoid the occurrence of VBNC bacteria.

Low-Temperature Mineralisation of Titania-Siloxane Composite Layers

This paper deals with low-temperature mineralisation of coatings made with titania-siloxane compositions (TSC). Methyltriethoxysilane has been adopted as the precursor for the siloxane, and during its synthesis, an oligomeric siloxane condensate with methyl moieties acting as TiO2 binder has been produced. These methyl moieties, contained in TSC, provide solubility and prevent gelling, but reduce the hydrophilicity of the system, reduce the transfer of electrons and holes generated in the TiO2. In order to avoid these unfavourable effects, TSC mineralisation can be achieved by nonthermal treatment, for example, by using UV-radiation or plasma treatment. Characterisation of the siloxane was performed by gel permeation chromatography (GPC), which showed the size of the siloxane chain. Thermogravimetric analysis revealed a temperature at which the siloxane mineralises to SiO2. Printed layers of two types of TSC with different siloxane contents were studied by a scanning electron microscope (SEM), where a difference in the porosity of the samples was observed. TSC on fluorine-doped tin oxide (FTO) coated glass and microscopic glass were treated with non-thermal UV and plasma methods. TSC on FTO glass were tested by voltammetric measurements, which showed that the non-thermally treated layers have better properties and the amount of siloxane in the TSC has a great influence on their efficiency. Samples on microscopic glass were subjected to a photocatalytic decomposition test of the model pollutant Acid orange 7 (AO7). Non-thermally treated samples show higher photocatalytic activity than the raw sample.

Impact of physical modifications on starch nutritional fractions: Rapidly Digestible Starch, Slowly Digestible Starch and Resistant Starch

The industrial utilization of native starches is limited because of their poor qualities and different starch modifications are used to improve functionality of starch. Physical modification of starch is preferred since it is simple, inexpensive, and specially it does not involve any chemical reagents. Physical modifications can be divided into thermal and non-thermal treatments. These techniques alter physicochemical properties of starch including in vitro digestibility, which indicates the nutritional value of starch. Starch nutritional fractions are of three types; RDS (rapidly digestible starch), SDS (slowly digestible starch) and RS (resistant starch). It is important to understand how physical modifications affect starch nutritional fractions as both SDS and RS have beneficial health effects and specially RS has the potential to be used as a natural bioactive compound. This review aims to summarize the recent knowledge regarding the physical modifications and their impact on in vitro digestibility and nutritional fractions of starch.

Mechanisms of Action And Effects of Pulsed Electromagnetic Fields (PEMF) in Medicine

Pulsed Electromagnetic Field (PEMF) therapy is a non-invasive and non-thermal treatment widely used nowadays to treat various types of disorders and traumas, both in humans and animals. Initially applied only for wound healing, today it finds many applications in medicine for the treatment of bone fractures, arthritis, inflammation, edema, and pain. Although their mechanisms of action are still being studied today, and mainly related to the calcium signaling pathway, they are effective in the adjuvant treatment of many human diseases in different medical specialties. This work aims to report the main evidence and research in the medical field with particular reference to the application of PEMF to some medical specialties as regenerative medicine (wound care), sports medicine, orthopedics, and physiotherapy. Finally, this work also wanted to deepen one of the most recent applications of PEMF in the field of complex diseases, i.e. in the adjuvant treatment of cancer. Pulsed electromagnetic field therapy may play an important role in medicine as a complementary treatment for various human diseases and, by deepening the studies in the future, it will be possible not only to understand the exact mechanisms of action but also to extend its application to other pathologies both in the medical and veterinary fields.

Effects of Industrial Thermal Treatments on the Release of Bovine Colostrum Glycoprotein N-Glycans by Endo-β-N-acetylglucosaminidase.

N-Glycans are structurally similar to human milk oligosaccharides, the gold standard prebiotics for infants. Bovine milk N-glycans released by endo-β-N-acetylglucosaminidase (EndoBI-1) were shown to have similar prebiotic selectivity as human milk oligosaccharides, explaining the interest for N-glycan recovery for use as prebiotics. Industrial thermal treatments such as high-temperature short-time (HTST) and ultra-high-temperature (UHT) might favor the enzymatic deglycosylation of N-glycans through promoting protein denaturation. We investigated the effects of HTST (72 °C for 15 s) and UHT (135 °C for 3 s) on N-glycan release from bovine colostrum glycoproteins by nonimmobilized and amino-immobilized EndoBI-1. A total of 104 N-glycans including isomers/anomers were identified by high-resolution mass spectrometry. In both EndoBI-1 forms, HTST increased the release of N-glycans; however, the impact of UHT on releasing N-glycans was comparable to the nonthermal treatment. Although the amino-immobilized enzyme similarly released neutral N-glycans as the free form, it released fewer sialylated and fucosylated N-glycans.

Changes in the milk serum proteome after thermal and non-thermal treatment

Milk serum contains many immune-active proteins that are sensitive to heat treatment. This study compared the effects of thermal (63 °C, 30 min; 72 °C, 15 s; 85 °C, 5 min) and non-thermal (ultraviolet-C, UV-C; thermo-ultrasonication, TUS) treatments on bovine milk serum proteins by using label-free LC-MS/MS-based proteomics. UV-C (4500 J/L) and TUS (60 W, 6 min) treatments achieved a 5log microbial reduction as determined by plate counting. Proteomics showed that e.g., complement proteins, xanthine dehydrogenase/oxidase, and fatty acid-binding protein decreased significantly (p˂0.05, |fold change|˃1) after thermal treatments, and almost no lactoferrin, immunoglobulin, and lactoperoxidase was retained after heating at 85 °C for 5 min, whereas these proteins were mostly retained after non-thermal treatments. Most of these heat-sensitive proteins were located in membrane and extracellular regions and were involved in cellular and metabolic processes, response to stimulus, binding, immune process and catalytic functions. Finally, part of the proteomics results were verified by ELISA. This study thus provided insights for the development of optimized thermal and novel non-thermal treatments for dairy processing. Industrial relevanceAs alternatives to thermal processing technique, UV-C and ultrasonication showed a great potential in the processing of milk. This study not only showed that UV-C and ultrasonication were able to largely reduce the microbial load of raw milk, but also better retained the immune-related milk serum proteins than thermal processing, especially for the UV-C treatment. ELISA assays also demonstrated that the LC-MS/MS based proteomics technology used in this study was a robust method for quantifying damage to the milk serum proteome upon processing. Taken together, this study provided insights for development of optimized thermal and novel non-thermal techniques for dairy processing.