Effect Of Pulsed Light Research Articles

Effect of pulsed light on enzyme inactivation, colour, firmness, surface morphology, and bioactive compounds in fresh and dried whole red chilies (Capsicum annuum var. longum)

The effect of pulsed light on enzymatic activity and biochemical stability of red chillies was investigated. Balancing and reducing the aw and moisture content to 0.6 aw and 0.35 aw is crucial to attain biochemical stability. Upon drying at 60 °C/5 h + 40 °C/2 h and 70 °C/11 h + 55 °C/4 h + 40 °C/2 h the enzymes inactivated to more than 30 %, respectively. Hence, to completely inactivate the enzymes, a technology has been introduced i.e., pulsed light treatment (PLT), which employed 0.53–2.59 J·cm−2. The stability of red chillies was evaluated based on the quality attributes such as enzyme activity, total phenolics, flavonoids, antioxidant capacity, ascorbic acid, capsiacinoids, and carotenoids. After treatment at fluence of 2.59 J·cm−2, there was >90 % inactivation of PPO and POD. Based on kinetic modelling, it is showed PLT better preserved the colour, texture, morphology, and bioactive compounds in 0.6 and 0.35 aw than 0.85 aw red chillies. Morphological studies determined the changes in red chillies after PLT. FTIR and GCMS analysis revealed the structural and compositional changes occurring after PLT. Therefore, drying combined with PL can be a potential alternative method to blanching along with maximizing the availability of bioactives.

Effect of pulsed light on curcumin chemical stability and antioxidant capacity.

Curcumin is the major bioactive component in turmeric with potent antioxidant activity. Little is known about how pulsed light (PL) technology (an emerging non-thermal food processing technology relying on high intensity short duration flashes of light) can affect the chemical stability and antioxidant capacity of curcumin. This study found that PL treatment of fluence levels from 0 to 12.75 J/cm2 produced a fluence-dependent reduction in curcumin content. These results paralleled the production of a tentative curcumin dimer, identified as a potential photochemical transformation product. PL-treated curcumin at relatively higher fluence levels decreased chemical-based ORAC and ABTS antioxidant capacity, relative to control (P < 0.05). This contrasted the effect observed to increase coincidently both intracellular antioxidant capacity (e.g., DCFH-DA (P < 0.05)) and GSH/GSSG ratio (P < 0.05), respectively, in cultured differentiated Caco-2 cells. In conclusion, the application of PL on curcumin results in photochemical transformation reactions, such as dimerization, which in turn, can enhance biological antioxidant capacity in differentiated Caco-2 cells.

Effect of pulsed light on myofibrillar protein of large yellow croaker (Pseudosciaena crocea) during refrigerated storage.

This study mainly evaluated the effect of different energies of pulsed light (PL) treatment (100, 200, 300, 400, and 500J/pulse) on myofibrillar protein (MP) of large yellow croaker during refrigerated storage. The results showed that PL treatment would cause a certain degree of oxidation to the MP of large yellow croaker at the initial stage, which showed that the total sulfhydryl content of the protein decreased, the carbonyl content and the average particle size increased, and the β-sheet to β-turn transformation, the tertiary structure of the protein unfolds, and the hydrophobic groups were exposed, causing the reduction of intrinsic fluorescence intensity. However, subsequent storage studies found that PL treatment could slow down the oxidation rate of MP. The decrease rate of total sulfhydryl content and the increase rate of carbonyl content in the 300J/pulse group were both reduced by about 1.7 times compared with the control group. At the same time, the PL treatment with this intensity could also better protect the secondary structure, tertiary structure, and microstructure of MP. This study provided theoretical basis and reference for analyzing the quality change rule and mechanism of large yellow croaker during refrigerated storage after PL treatment. Studies have shown that PL treatment can reduce the adverse changes of MP in large yellow croaker during cold storage.

Effects of pulsed light on the post­harvest quality and shelf-life of highbush blueberries (cv. Draper)

Blueberry consumption has been a burgeoning interest attributed to their nutritional and health benefits. However, the main limitation to blueberry marketability is their perishability due to water loss, fungal, and mechanical damage during post-harvest preservation. In this study, pulsed light (PL) treatments with doses of 3, 6 and 9 J cm-2 were applied in the 6-week storage of highbush blueberry (cv. Draper) at 0.5°C under 90-95% relative humidity (RH) conditions. The quality changes of berry were assessed by using physicochemical attributes and antioxidant activity bi-weekly at week 0, 2, 4, 6. The results show that in spite of the partial loss of the antioxidant activity and total soluble solids (TSS), PL at dose of 6 J cm-2 was found to increase firmness and titratable acidity (TA), and decrease weight loss, rot incidence, and pH during post-harvest storage, which lead to a better maintenance of blueberry quality and shelf-life extension.

Pulsed light reduces postharvest losses of Chinese bayberries by affecting fungal microbiota during cold storage

Non-thermal sterilization technology is considered a safe and effective approach in controlling postharvest losses of fruit. In this study, the effects of pulsed light (PL) on qualities of Chinese bayberries during storage at 10 °C, 95% RH for 12 d were investigated. At the same time, high-throughput sequencing was operated to identify fungal microbiota on Chinese bayberries. The results showed that PL treatment could inhibit the decay incidence and polyphenol oxidase (PPO) activity, maintain fruit firmness and enhance phenylalanine ammonia-lyase (PAL) activity, with no effect on titratable acid (TA), total soluble solids (TSS), malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. Additionally, the PL treatment maintained alpha diversity and altered beta diversity. At the species level, the abundance of Monographella nivalis and Colletotrichum cordylinicota were reduced in PL samples, while Hanseniaspora uvarum and Diaporthe spp were enriched. M. nivalis and C. cordylinicota were positively correlated with weight loss and decay index according to canonical correspondence analysis (CCA). The data of microbial correlation network indicated that PL treatment reduced pathogenic fungal microbiotas and made fungal community more complex and steadier. This study demonstrated that PL affects fungal community by inhibiting plant pathogens, increasing the amounts of endophytes and consolidating microbial networks. It provides new insights into the dynamics of the microbiome of Chinese bayberries after PL treatment.

Effects of pulsed light and aerosolized formic acid treatments on inactivation of Salmonella enterica on cherry tomato, reduction of microbial loads, and preservation of fruit quality

Fresh produce remains the leading cause of foodborne illness outbreaks. Novel nonthermal technologies are needed to reduce the risk of pathogen contamination. The objective of this study was to develop a novel intervention technology exploiting integration of high intensity short time (10 s) pulsed light (PL) and aerosolized formic acid (AFA) for inactivation of Salmonella and maintenance of quality of cherry tomato. Smooth surface of tomatoes, inoculated with a cocktail containing three serotypes of Salmonella enterica, was treated with PL for 10 s followed by 2 min treatment with 1% AFA. Non-inoculated tomatoes were used to study the treatment effects on native microflora and quality. PL delivered significant inactivation at low doses. An optimal 10 s PL treatment equivalent to a dose of 10.5 J/cm2, provided 2.2 log CFU/g reduction while a 2 min exposure in 1% AFA antimicrobial yielded comparatively low, 1.7 log CFU/g reductions of Salmonella on tomato. The combination treatments of PL (10 s) followed by 1% AFA (2 min) provided additive inactivation yielding 4.2 log CFU/g reductions (P ≤ 0.05) of the pathogen. During cold storage (10 °C) the survivor population declined further providing 4.8 log CFU/g reductions on day 21. The combination PL-AFA treatment significantly reduced the native microbiota of tomato and also hindered their growth while in storage for three weeks. Mold and yeast (M&Y) spoilage organism populations declined to below the detection level. Furthermore, the quality factors as firmness and color of tomatoes were not significantly affected by the combination treatments. The treatment boosted the redness appearance of tomatoes indicating favorable consumer acceptability. Overall, our results demonstrate that combination of PL and AFA treatment could potentially be used as a novel approach to enhance microbial safety and quality of tomatoes.

Effect of pulsed light on microbial inactivation, sensory properties and protein structure of fresh ricotta cheese

Ricotta cheese was subjected to PL treatments at increasing fluence (1.3, 3.1, 7.5, 15.0 J/cm2) and stored at 4 °C. Just treated samples presented microbial counts (Pseudomonas spp., Enterobacteriaceae, yeasts) lower than those of the untreated one. PL at 1.3 and 3.1 J/cm2 allowed delaying microbial spoilage during storage but higher fluences favoured microbial growth and off-odour formation, probably due to the surface nature of PL technology. The penetration depth of the UV-C fraction of PL resulted of only 1.5 mm, hindering microbial inactivation at the core and promoting local modification of ricotta cheese constituents. FTIR, SDS-PAGE and DLS analysis demonstrated that PL induced the formation of small protein particles, able to interact with lipids and carbohydrates, and rearrange into larger aggregates. Aggregation reduced protein solubility and occurred following exposure of hydrophobic protein groups, enhancement in S–S bonding and changes in α-helix and β-sheets structures. Proteins photoreaction was confirmed by the formation of melanoidins and carbonyls.

Effect of pulsed light on postharvest disease control-related metabolomic variation in melon (Cucumis melo) artificially inoculated with Fusarium pallidoroseum.

Pulsed light, as a postharvest technology, is an alternative to traditional fungicides, and can be used on a wide variety of fruit and vegetables for sanitization or pathogen control. In addition to these applications, other effects also are detected in vegetal cells, including changes in metabolism and secondary metabolite production, which directly affect disease control response mechanisms. This study aimed to evaluate pulsed ultraviolet light in controlling postharvest rot, caused by Fusarium pallidoroseum in ‘Spanish’ melon, in natura, and its implications in disease control as a function of metabolomic variation to fungicidal or fungistatic effects. The dose of pulsed light (PL) that inhibited F. pallidoroseum growth in melons (Cucumis melo var. Spanish) was 9 KJ m–2. Ultra-performance liquid chromatography (UPLC) coupled to a quadrupole-time-of-flight (QTOF) mass analyzer identified 12 compounds based on tandem mass spectrometry (MS/MS) fragmentation patterns. Chemometric analysis by Principal Components Analysis (PCA) and Orthogonal Partial Least Squared Discriminant Analysis (OPLS-DA) and corresponding S-Plot were used to evaluate the changes in fruit metabolism. PL technology provided protection against postharvest disease in melons, directly inhibiting the growth of F. pallidoroseum through the upregulation of specific fruit biomarkers such as pipecolic acid (11), saponarin (7), and orientin (3), which acted as major markers for the defense system against pathogens. PL can thus be proposed as a postharvest technology to prevent chemical fungicides and may be applied to reduce the decay of melon quality during its export and storage.

Effect of pulsed light on shelf life of chill stored yellowfin tuna (Thunnus albacares) steaks

In this study, the effect of pulsed light (PL) treatment on the shelf life extension of yellowfin tuna (Thunnus albacares) steaks was investigated. Tuna steaks of 1 cm thickness weighing 80 g packed in 300 gauge cast polypropylene pouches were subjected to PL treatment using Xenon pulse light machine RC-847. The samples were stored at 2±1OC and analysed at specific time intervals. Shelf life studies were carried out in terms of reduction of aerobic flora as inferred from the total plate count (TPC) and the psychrophilic count. The samples were also evaluated in terms of colour (L*, a* and b*), biochemical and sensory parameters. The initial reduction as well as lower rate of increase in the microbial count on the PL treated samples clearly highlighted the efficiency of PL technology as a novel non-thermal preservation technique. Low values of chemical indicators of spoilage and better values of sensory and colour values of PL treated samples also suggested the efficacy of PL treatment in microbial inactivation. An overall extension of 13 days of shelf life was achieved for PL treated samples whereas control samples were rejected on 13th day

Effects of pulsed light and sanitizer wash combination on inactivation of Escherichia coli O157:H7, microbial loads and apparent quality of spinach leaves

The purpose of this study was to investigate the efficacy of pulsed light (PL), a new formula of sanitizer (HEN) consisting of hydrogen peroxide, EDTA and Nisin, as well as synergy of PL and HEN sanitizer (PL-HEN) wash in inactivating E. coli O157:H7 on spinach. The treatment effect on microbial loads and apparent quality during 13 days storage at 4 °C was also determined. A bacterial cocktail containing three strains of E. coli O157:H7 was used as inoculum based on their association with produce-related outbreaks. Spinach leaves were spot inoculated on surface before treating with PL (1–63J/cm2), HEN sanitizer wash (2 min) or their combinations. PL inactivation was influenced significantly at low doses. Treatment dose of 15.75 J/cm2, equivalent to 15 s intense PL treatment, was found optimal above which adverse quality effect was evident. The optimal PL dose resulted 2.7 log CFU/g reduction of E. coli O157:H7 while a rapid 2 min wash in sanitizer formulation HEN, provided comparatively low, 1.8 log CFU/g, reduction of the pathogen. Two different sequences of PL and HEN treatment combinations were tested. In PL-HEN treatment, inoculated leaves were first treated at optimal PL dose (15.75 J/cm2) followed by 2 min immersion in HEN whereas in HEN-PL treatment, leaves were first washed in HEN before PL exposure. HEN-PL treatment indicated a compound inactivation activity (4.6 logs reduction) while PL-HEN treatment indicated a strong synergistic inactivation as E. coli cells were not detectable after treatment indicating >5 log reduction. The PL-HEN treatment not only significantly reduced spoilage microbial populations on spinach but also slowed their growth during storage. Furthermore, the visual and firmness quality of spinach were not significantly affected by the PL-HEN treatment. Overall, our results demonstrate that integrated PL-HEN technology can be used to enhance microbial safety of spinach.

Kinetics of the changes in the antioxidant potential of fresh-cut tomatoes as affected by pulsed light treatments and storage time

The effects of pulsed light (PL) on the antioxidant capacity (AC) and bioactive compounds content of fresh-cut tomatoes (Lycopersicon esculentum Mill., cv. Daniela) were studied. Tomato slices were subjected to fluences of 4, 6 and 8 J cm−2 and stored over 18 days. Modified first-order and Gompertzian functions were used to explain the changes in the studied parameters as affected by PL-fluence and storage time.PL processing led to an increase in the contents of lycopene (up to 26.1% higher) and phenolic compounds (up to 4.3% higher) in comparison with untreated tomato slices, while vitamin C was notoriously depleted (p < 0.05). Those patterns were properly fitted by linear equations (R2 ≥ 0.95), while changes in the bioactive compounds contents through storage were well described by Gompertzian functions (R2adj≥ 0.94 and Af ≥ 0.99). AC of tomato slices significantly decreased as a consequence of PL-processing (p < 0.05) and subsequent storage (p < 0.05). The influence of PL on the initial AC of tomato slices was expressed by a linear model (R2 ≥ 0.95) while changes through storage were appropriately fitted by a first-order equation (R2adj ≥ 0.95 and Af ≥ 0.99). The higher the fluence applied, the greater the change in the AC and bioactive compounds contents of tomato slices over storage. The high correlation coefficients and the estimated kinetic constants seem to suggest that changes in the AC of PL-treated tomato slices over storage were mostly determined by vitamin C concentrations (r = 0.93–0.97) rather than by other antioxidant contents (r = −0.59 − −0.76). Industrial relevance:The efficacy of pulsed light (PL) to reduce microbial loads on fresh-cut vegetables is widely known. However, information about the impact of PL treatments on the physicochemical and nutritional aspects of those commodities is scarce. The results obtained in this work may contribute to identify optimal PL-treatment conditions to achieve healthy and fresh-like cut tomatoes. In general, tomato slices exposed to the highest PL-fluence (8 J cm−2) exhibited significant increases in lycopene and total phenolic contents, thus minimizing losses in the antioxidant capacity of fresh-cut tomatoes through 18 days of chill storage.

Total inactivation of lipoxygenase in whole soya bean by pulsed light and the effect of pulsed light on the chemical properties of soya milk produced from the treated soya beans

AbstractThe inactivation of lipoxygenase (LOX) in the whole soya bean prevents lipid oxidation that produces an off‐flavour of soya food. The inactivation of lipoxygenase in the whole soya bean by pulsed light (PL) was examined with three distances (5, 7 and 9 cm) from the PL strobe and for different durations. Soya bean was treated with PL with and without ice surrounding the soya bean sample tray for limiting the rise in sample temperature. Results show that without ice surrounding the sample tray, the lowest LOX residual activity was 4.7%, 0.4% and 0.0% for 80‐s duration at 5 cm distance from the PL strobe, 110 s at 7 cm from the strobe and 150 s at 9 cm from the strobe, respectively; the soya bean temperature after treatment was 109.6, 116.3 and 114.8 °C, respectively. The instantaneous temperatures of the soya bean core measured during PL operating were above 100 °C. The lipoxygenase band was disappeared after longest PL treatments of each distance compared with the LOX band control as assessed by electrophoresis. The pulsed light had no negative effect on peroxide value of produced soya milk. However, PL reduced significantly the total solid amount and changed the colour of the produced soya milk. The residual activity with sample cooling by ice during treatment was 79.0%, 98.8% and 95.7%, with sample temperatures of 81.7, 91.2 and 66.9 °C, respectively. This study indicates that PL illumination could fully inactivate LOX in whole soya beans, with the photo‐thermal effect of PL as the main factor responsible for the inactivation of LOX.

Impact of pulsed light treatments and storage time on the texture quality of fresh-cut tomatoes

Abstract The effect of pulsed light (PL) treatments at fluences of 4, 6 or 8 J cm − 2 on microbial growth, weight loss, pectinmethyl esterase (PME) and polygalacturonase (PG) activities of fresh-cut tomatoes was evaluated through 20 days of storage at 5 °C. Additionally, a pair-wise comparison test was assayed to determine whether potential consumers could detect differences between untreated and PL-treated samples. Microbial counts of PL-treated tomato slices were up to 2 Log CFU g lower than those on untreated samples over storage. Fresh-cut tomatoes exhibited slight firmness decrements, changes in the pectinolytic enzymes and increased weight losses over the storage. However, sensory evaluation did not reveal significant differences over at least 10 days. In summary, PL-treatments showed to be effective to reduce the microbial growth with a low impact on the physical quality of fresh-cut tomatoes. Industrial relevance PL-treatments are proposed as a non-thermal strategy to increase the safety of fresh-cut commodities. In spite of their non-thermal nature, these treatments may have a photothermal effect, which could be deleterious to the product quality and shelf-life. This study contributes to the understanding of PL and its impact on the physical quality of fresh-cut tomatoes, thus helping to identify the range of conditions that can be industrially applied without causing major texture damage on the treated product.

Pulsed light processing of foods for microbial safety

The demand for processed foods and the awareness about food quality and safety are increasing rapidly. The consumers’ demand for minimally processed foods and growing competition in the market have made the processors to adopt newer non-thermal technologies that preserve nutrients and sensory properties of the products. Conventionally, heat processing of foods is carried out to convert raw material into value-added product, reduce or eliminate microbial load to improve safety, and extend shelf life. Some of the limitations of thermal processing techniques can be overcome by employing non-thermal processes. High hydrostatic pressure, pulsed electric field, ultrasound, cold plasma, dense phase carbon dioxide, ozone, and pulsed light (PL) processing are gaining popularity in food processing. PL technology is a non-thermal technology, where sterilization and decontamination are achieved by impinging high-intensity light pulses of short durations on surfaces of foods and high-transmission liquids. Although a few reports on the PL technology are available, in-depth studies on this are needed to adopt at a commercial level. The present review provides an overview of light-based processing of foods and covers important aspects such as different PL systems used for processing of foods, mode of action of PL on microbes, the effect of PL on liquid foods, surface decontamination of foods and parameters that affect PL efficacy, combination processing with PL. With the growing demand in non-thermal processing for the technological advancement in the area of generation of light, light-based processing will be a promising technology for microbial load reduction.

Influence of pulsed light treatment on the aggregation of whey protein isolate

The effect of pulsed light (PL) on the aggregation of whey protein isolate (WPI) solutions was investigated. PL fluence values from 4 to 16J/cm2 were used to treat WPI (1% w/v) solutions in sodium phosphate buffer (pH=7.5). Whey protein structural modification and aggregation were assessed through the determination of free SH-groups and UV-absorption spectra. Additionally, covalent and non-covalently linked protein-protein interactions were identified through the measurement of turbidity, aggregation index, particle size distribution, and SDS-PAGE.WPI upon PL treatment showed structural changes as demonstrated by the immediate increase of free SH-group content (unfolding) and the subsequent formation of a small fraction of aggregation of unfolded proteins, due to both hydrophobic interactions and the formation of disulphide bonds. Turbidity, mean particle size, and aggregation index increased in samples treated at PL fluence from 4 to 16J/cm2. Furthermore, particle size distribution analysis of samples treated at higher fluence indicated that WPI dimer dissociation and formation of larger particles were likely to occur. The association of intermediate and larger protein molecules as well as the formation of soluble aggregates between β-lactoglobulin and α-lactalbumin were also observed in gel electrophoresis analysis. In conclusion, the results of this investigation demonstrated the potential of PL treatments to induce protein denaturation, with a minimal formation of soluble protein aggregates.

EFFECT OF PULSED LIGHT ON SELECTED PROPERTIES OF CUT APPLE

The effect of pulsed light (0, 8.8 and 17.5 J cm-2) on selected properties of cut apple (thermal power, oxygen consumption, volatile compounds, colour and firmness) was investigated during storage at 30 °C for up to 6 days. Samples exposed to pulsed light showed lower heat production due to a decrease in tissue respiration. Pulsed light treated samples also showed different evolution of volatile compounds (ethanol, acetaldehyde and ethyl acetate), browning and tissue softening. Modification of tissue metabolisms by pulsed light could be exploited in the processing of fresh-cut fruit and vegetables leading to advantages well beyond its germicidal activity.

Modelling for the Survival of Escherichia coli in Tender Coconut (Cocos nucifera l.) Water by Non-thermal Pulsed Light Treatment

The effect of pulsed light on the survival of E.coli MTCC 433 in tender coconut water was investigated. The sterilized liquid samples were inoculated with E.coli @ 1010 cfu/ml and treated with pulsed light intensities of 0.18, 2 and 5.6 W/cm2 for an exposure time between 0 and 15 sec. The results obtained were fitted with three different models such as log linear plus tail, Weibull and biphasic model. Biphasic model showed the best the performance with 7 smaller RSME values of 9 evaluated kinetics followed by Weibull model. Among the three models, biphasic model fitted well with the inactivation of E.coli MTCC 433 by using pulsed light treatment

Modeling the Inactivation of Listeria innocua and Escherichia coli in Fresh-Cut Tomato Treated with Pulsed Light

The effectiveness of pulsed light (PL) treatments to inhibit microorganisms on fresh-cut tomatoes (Lycopersicon esculentum Mill., cv. Daniela) was investigated. Tomato slices inoculated with Escherichia coli or Listeria innocua were exposed to PL treatments (4, 6, or 8 J cm−2 fluence) and kept cold at 4 °C for 20 days. L. innocua and E. coli counts, gases in the headspace of the containers (O2 and CO2), pH, titratable acidity, and soluble solid content were monitored throughout the cold storage. The PL treatments reduced significantly (p < 0.05) initial loads of both microbes. The effect of the PL fluence on the survival number of microoganisms was described by a log-linear model (R 2 = 0.849–0.999). At any fixed time within the cold storing, the microbial counts for untreated samples were always higher than those cut tomatoes that had been previously PL-treated. The behavior of L. innocua and E. coli during the storage were well adjusted (R 2 > 0.930) by Gompertzian models; the studied microorganisms exhibited different patterns during the storage period. On the other hand, O2 and CO2 partial pressures in containers with fresh-cut tomatoes were also significantly affected by PL treatments (p < 0.05). The highest PL fluence caused the greatest changes of O2 and CO2 contents. In addition, the application of PL triggered an acceleration of the O2 consumption during the cold stage. PL treatments might be used to effectively extend the safety of fresh-cut tomatoes over 12 days of storage against E. coli and L. innocua growth.

Impact of pulsed light treatments on antioxidant characteristics and quality attributes of fresh-cut apples

Abstract The effects of pulsed light (PL) treatments combined with a quality-stabilizing dip on the quality and antioxidant attributes of fresh-cut ‘Golden delicious’ apples was studied. Apple wedges were dipped into a solution of 1% w / v N-acetylcysteine and 0.5% w / v CaCl 2 and flashed with broad-spectrum light with an overall radiant exposure of 4, 8, 12 and 16 J . cm −2 . General microbial counts, colour, firmness, phenolic compounds and vitamin C contents were evaluated over 15 days at 5 °C. More pronounced reductions of the naturally-occurring microbiota were observed as the applied PL-dose increased. The quality-stabilizing pre-treatment effectively prevented browning phenomena on the cut-tissue surface. In addition, browning and oxidation were not promoted in PL flashed samples. Indeed, the initial contents in phenolic compounds and vitamin C were even better maintained than in untreated samples. Treatments of 8 and 16 J cm −2 were most effective for maintaining the quality and antioxidant characteristics. Industrial relevance Pulsed light technology is an emerging technique with good prospects for the decontamination of foods and food contact surfaces. Application of pulse light treatments for increasing safety and extending microbial shelf life of fresh-cut produce seems feasible. However, their effects on the quality and antioxidant characteristics of fruit need to be evaluated for successfully applying the technology at an industrial level.

Effect of pulsed light on structure and immunoreactivity of gluten

The effect of pulsed light (from 1.75 to 26.25Jcm−2) on selected properties of wheat gluten powder and aqueous suspension (absorbance, particle size and microstructure, free sulfhydryl content, protein fractions, protein electrophoretic mobility and immunoreactivity) was investigated. Gluten photoreactivity was strongly affected by hydration. While minor photo-induced structure modifications were observed in gluten powder, pulsed light induced the development of browning and promoted partial depolymerisation of hydrated gluten proteins by disulphide exchange. These changes were associated with a significant decrease in immunoreactivity, suggesting that pulsed light could be exploited to efficiently modify structure and thus functionality of gluten.