Structural Changes Imposed on Whey Proteins by UV Irradiation in a Continuous UV Light Reactor

Kristo, Eleana; Hazizaj, Artan; Corredig, Milena

doi:10.1021/jf300278k

Cited by 101 publications

(47 citation statements)

References 23 publications

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“…The finding that UV-C irradiation caused less damage to proteins than thermal pasteurization agrees with a previous study conducted with whey protein solutions [37]. We have recently shown that a dosage of 4863 J/l reduces vegetative bacteria by 5-log 10 in human milk with a high total solids content without the loss of BSSL, ALP and fatty acids [29].…”

Section: Discussionsupporting

confidence: 88%

The Effect of UV-C Pasteurization on Bacteriostatic Properties and Immunological Proteins of Donor Human Milk

et al. 2013

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BackgroundHuman milk possesses bacteriostatic properties, largely due to the presence of immunological proteins. Heat treatments such as Holder pasteurization reduce the concentration of immunological proteins in human milk and consequently increase the bacterial growth rate. This study investigated the bacterial growth rate and the immunological protein concentration of ultraviolet (UV-C) irradiated, Holder pasteurized and untreated human milk.MethodsSamples (n=10) of untreated, Holder pasteurized and UV-C irradiated human milk were inoculated with E. coli and S. aureus and the growth rate over 2 hours incubation time at 37°C was observed. Additionally, the concentration of sIgA, lactoferrin and lysozyme of untreated and treated human milk was analyzed.ResultsThe bacterial growth rate of untreated and UV-C irradiated human milk was not significantly different. The bacterial growth rate of Holder pasteurized human milk was double compared to untreated human milk (p<0.001). The retention of sIgA, lactoferrin and lysozyme after UV-C irradiation was 89%, 87%, and 75% respectively, which were higher than Holder treated with 49%, 9%, and 41% respectively.ConclusionUV-C irradiation of human milk preserves significantly higher levels of immunological proteins than Holder pasteurization, resulting in bacteriostatic properties similar to those of untreated human milk.

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Section: Discussionsupporting

confidence: 88%

The Effect of UV-C Pasteurization on Bacteriostatic Properties and Immunological Proteins of Donor Human Milk

et al. 2013

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“…The limited ability of UV light to penetrate turbid liquids has affected its use as a nonthermal technology for milk (Kristo et al, 2012). Short-wave UV light (UV-C; 200−280 nm) offers one of the most promising nonthermal continuous flow treatments that could provide milk processors with a safe, energy-efficient, and cost-effective way to gain an added measure of quality and extended shelf life due to its lethal activity against most microorganisms, including bacteria, viruses, and parasites (Bintsis et al 2000).…”

Section: Introductionmentioning

confidence: 99%

“…The knowledge of extent of the changes in composition and potential formation of undesired compounds is particularly important for regulatory approvals of novel processing methods such as UV. In a study on structural changes imposed on whey proteins by UV treatment in a continuous UV light system (Taylor-Couette-type UV system (Trojain UV, London, ON, Canada) with a 254-nm UV-C lamp and power of 3.8 W) with solutions pumped through the reactor at 30, 40, 70, 130, and 800 mL/min at the UV dose levels from 7,600 to 285 J/L, intrinsic fluorescence spectra and surface hydrophobicity measurements suggested changes in the tertiary structure of the proteins with UV exposure (Kristo et al, 2012). A study that investigated the effects of UV processing as an alternative to heat treatment of milk using a custom-made UV system (stainless steel reflector, a corrugated teflon tube coiled around a quartz sleeve with 9 UV-C lamps, 254 nm, 87 W, and UV dose of 13,870 J/L per single pass), found no major differences in terms of aroma-active compounds and flavor of milk following UV treatment, although some new volatiles and change in rheological properties were generated (Engin and Yuceer, 2012).…”

Section: Introductionmentioning

confidence: 99%

Chemical characterization of milk after treatment with thermal (HTST and UHT) and nonthermal (turbulent flow ultraviolet) processing technologies

Cappozzo

Koutchma

Barnes³

2015

Journal of Dairy Science

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As a result of growing interest to nonthermal processing of milk, the purpose of this study was to characterize the chemical changes in raw milk composition after exposure to a new nonthermal turbulent flow UV process, conventional thermal pasteurization process (high-temperature, short-time; HTST), and their combinations, and compare those changes with commercially UHT-treated milk. Raw milk was exposed to UV light in turbulent flow at a flow rate of 4,000L/h and applied doses of 1,045 and 2,090 J/L, HTST pasteurization, and HTST in combination with UV (before or after the UV). Unprocessed raw milk, HTST-treated milk, and UHT-treated milk were the control to the milk processed with the continuous turbulent flow UV treatment. The chemical characterization included component analysis and fatty acid composition (with emphasis on conjugated linoleic acid) and analysis for vitamin D and A and volatile components. Lipid oxidation, which is an indicator to oxidative rancidity, was evaluated by free fatty acid analysis, and the volatile components (extracted organic fraction) by gas chromatography-mass spectrometry to obtain mass spectral profile. These analyses were done over a 14-d period (initially after treatment and at 7 and 14 d) because of the extended shelf-life requirement for milk. The effect of UV light on proteins (i.e., casein or lactalbumin) was evaluated qualitatively by sodium dodecyl sulfate-PAGE. The milk or liquid soluble fraction was analyzed by sodium dodecyl sulfate-PAGE for changes in the protein profile. From this study, it appears that continuous turbulent flow UV processing, whether used as a single process or in combination with HTST did not cause any statistically significant chemical changes when compared with raw milk with regard to the proximate analysis (total fat, protein, moisture, or ash), the fatty acid profile, lipid oxidation with respect to volatile analysis, or protein profile. A 56% loss of vitamin D and a 95% loss of vitamin A content was noted after 7 d from the continuous turbulent flow UV processing, but this loss was equally comparable to that found with traditional thermal processing, such as HTST and UHT. Chemical characterization of milk showed that turbulent flow UV light technology can be considered as alternative nonthermal treatment of pasteurized milk and raw milk to extend shelf life.

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“…[45] Dityrosine formation has also been observed to occur in proteins exposed to 365 nm UV light with riboflavin,[64] and in this manuscript, but also with high energy (254 nm) UV light alone, too high for use with biologics. [65] Further, riboflavin has been used to crosslink collagen, particularly in the eye to treat keratoconus. [66–68] This method relies on the same photochemistry used in this report to crosslink tyrosine residues in native collagen, and was determined to be a safe and effective method to treat keratoconus in a 1 year follow-up study.…”

Section: Resultsmentioning

confidence: 99%

Photocrosslinked tyramine-substituted hyaluronate hydrogels with tunable mechanical properties improve immediate tissue-hydrogel interfacial strength in articular cartilage

Donnelly

Chen

Finch

et al. 2017

Journal of Biomaterials Science, Polymer Edition

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Articular cartilage lacks the ability to self-repair and a permanent solution for cartilage repair remains elusive. Hydrogel implantation is a promising technique for cartilage repair; however for the technique to be successful hydrogels must interface with the surrounding tissue. The objective of this study was to investigate the tunability of mechanical properties in a hydrogel system using a phenol-substituted polymer, tyramine-substituted hyaluronate (TA-HA), and to determine if the hydrogels could form an interface with cartilage. We hypothesized that tyramine moieties on hyaluronate could crosslink to aromatic amino acids in the cartilage extracellular matrix. Ultraviolet (UV) light and a riboflavin photosensitizer were used to create a hydrogel by tyramine self‐crosslinking. The gel mechanical properties were tuned by varying riboflavin concentration, TA-HA concentration, and UV exposure time. Hydrogels formed with a minimum of 2.5 min of UV exposure. The compressive modulus varied from 5–16 kPa. Fluorescence spectroscopy analysis found differences in dityramine content. Cyanine-3 labelled tyramide reactivity at the surface of cartilage was dependent on the presence of riboflavin and UV exposure time. Hydrogels fabricated within articular cartilage defects had increasing peak interfacial shear stress at the cartilage-hydrogel interface with increasing UV exposure time, reaching a maximum shear stress 3.5× greater than a press‐fit control. Our results found that phenol-substituted polymer/riboflavin systems can be used to fabricate hydrogels with tunable mechanical properties and can interface with the surface tissue, such as articular cartilage.

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Structural Changes Imposed on Whey Proteins by UV Irradiation in a Continuous UV Light Reactor

Cited by 101 publications

References 23 publications

The Effect of UV-C Pasteurization on Bacteriostatic Properties and Immunological Proteins of Donor Human Milk

The Effect of UV-C Pasteurization on Bacteriostatic Properties and Immunological Proteins of Donor Human Milk

Chemical characterization of milk after treatment with thermal (HTST and UHT) and nonthermal (turbulent flow ultraviolet) processing technologies

Photocrosslinked tyramine-substituted hyaluronate hydrogels with tunable mechanical properties improve immediate tissue-hydrogel interfacial strength in articular cartilage

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