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Consumers of the 21st century tend to be more aware and demand safe as well as nutritionally balanced food. Unfortunately, conventional thermal processing makes food safe at the cost of hampering nutritional value. The food industry is trying to develop non-thermal processes for food preservation. Pulsed light (PL) is one such emerging non-thermal food processing method that can decontaminate food products or food contact surfaces using white light. Exposure to intense light pulses (in infrared, visible, and ultraviolet (UV) regions) causes the death of microbial cells, rendering the food safe at room temperature. PL technology is an excellent and rapid method of disinfection of product surfaces and is increasingly being used for food surfaces and packaging decontamination, enabling the minimal processing of food. This paper aims to give an overview of the latest trends in pulsed light research, discuss principles of pulse generation, and review applications of various PL systems for the inactivation of microorganisms in vitro, in various food products, and on food contact surfaces. Effects of PL on food quality, challenges of the process, and its prospects are presented.

Tea-based ready-to-drink (RTD) beverages have been commercialized in recent years, which are usually preserved by conventional thermal processes. However, intense thermal processing can significantly affect their sensory and nutritional quality. Pulsed UV light processing has emerged as a potent non-thermal technology for processing of liquid foods, which can be applied as a hurdle approach with milder thermal processing. This makes it important to study the effects of the pulsed UV light on quality of tea. Therefore, this study was carried out to assess the effect of pulsed UV light on black tea infusions (at two different concentrations—1:100 w/v and 1:50 w/v). The pulse frequency (1–10 Hz) and treatment time (5–50 s) were varied to impart pulsed light fluence in the range 1.07–17.2 J/cm 2 , and their effect on physico-chemical properties, total phenolic content, and antioxidant activity of tea infusions were studied. The temperature and color of the samples were significantly affected, whereas the total phenolic content and antioxidant activity remained mostly unaffected. The effects of the processing variables were also analyzed using response surface methodology and optimized treatment conditions were determined. Overall, pulsed UV light treatment can be used to assist thermal processing of polyphenol-rich liquid foods.

Lipoxygenase (LOX) is a widely distributed enzyme in plant and animal cells. It catalyzes the oxidation of polyunsaturated fatty acid into fatty acid hydroperoxides. LOX is also associated with the production of aroma substrates, color changes, and alternation of physico‐chemical characteristics. The associated reaction could be either desirable or undesirable in food production. An understanding of LOX characteristics and functional principles is essential for utilizing LOX as a natural food ingredient. Legumes are nutrient‐dense food ingredient and also serve as a good source of LOX. This paper is focused on the biological function of LOX in legumes, the history of legume LOX, the application of legume LOX in the food industry, and the inhibition strategies of unwanted LOX‐catalyzed reaction.

Radiant Energy Vacuum (REV)-dried broccoli, oranges, and carrots prepared by the optimal drying protocols determined in this study were compared to the freeze-dried and air-dried samples based on the nutritional values before and after drying. An accelerated shelf-life study for REV-dried broccoli, oranges, and carrots was also conducted. For all the samples, REV drying significantly shortened the processing time. The REV-dried samples had much higher retention of the nutritional values (vitamin C, β-carotene) compared to the conventional air-drying process, and the values were also competitive to those of the freeze-dried samples. Although freeze-drying resulted in the best rehydration property, the REV-dried samples still earned the highest scores in the sensory test. In the accelerated shelf-life study conducted on the REV-dried samples, the moisture content and water activity stayed at the same level, but the nutritional values showed a downward trend. The sensory properties fluctuated in the shelf-life but still gained positive feedback from the panelists. Moreover, the testing method for β-carotene content was uniquely designed in this project and could be a semi-quantitative method to refer to.

Pulsed light (PL) is one of the most promising non-thermal technologies used in food preservation and processing. Its application results in reduction of microbial load as well as influences the quality of food. The data about the impact of PL on bioactive compounds is ambiguous, therefore the aim of this study was to analyze the effect of PL treatment of a gallic acid aqueous solution—as a model system of phenolic abundant liquid food matrices. The effect of PL treatment was evaluated based on colour, phenolic content concentration and antioxidant activity measured by DPPH assay using a design of experiments approach. The PL fluence (which is the cumulative energy input) was varied by varying the pulse frequency and time. Using Response Surface Methodology, prediction models were developed for the effect of fluence on gallic acid properties. It was demonstrated that PL can modify the optical properties of gallic acid and cause reactions and degradation of gallic acid. However, application of PL did not significantly alter the overall quality of the model gallic acid solution at low fluence levels. Cluster analysis revealed that below 3.82 J/cm2, changes in gallic acid were minimal, and this fluence level could be used as the critical level for food process design aiming to minimize nutrient loss.

In this study, the effect of pulsed UV light (PUV) (emission wavelength: 200–1100 nm) treatment parameters (flow rate, 14.3–74.9 L/h; pulse frequency, 1–5 Hz; reactor configuration, annular (AT) and coiled tube (CT)) on microbial susceptibility in model liquids with different optical properties (water, water + red dye, water + green dye, skim milk) inoculated with test microorganisms ( Escherichia coli , Listeria innocua , Clostridium sporogenes ) was studied. Total delivered fluence during each treatment was computed using an innovative computational fluid dynamic (CFD) method and correlated with the analytical microbial inactivation kinetics data. D -value of microorganisms and corresponding reduction equivalent fluence in tested liquids were determined by collimated beam experiment. Total delivered fluence calculated using CFD were 5.45, 4.67, 4.47, and 4.46 J/cm 2 in AT reactor and 17.05, 25.83, 21.14, and 22.47 J/cm 2 for CT reactor in water, water + red dye, water + green dye, and skim milk, respectively. Microbial inactivation was a function of optical properties of the liquids (inactivation in water > water + red dye > water + green dye > skim milk) and reactor configuration (inactivation in CT reactor was significantly higher than AT reactor, p  < 0.05). Reduction of > 7 log 10 for all the microorganisms was achieved for water and water + added dyes in CT reactor, whereas > 3.5 log 10 reduction was achieved for all the microorganisms in skim milk. Microorganisms D -value was significantly varied ( p  < 0.05) among the microorganisms ( E. coli  >  L. innocua  >  C. sporogenes ). Overall, these results demonstrate the applications of PUV for treatment of liquid food with different optical properties and shall serve as a benchmark for commercialization of PUV reactors for juices, and beverages. Graphical Abstract

Pulsed light (PL) is a novel, non-thermal technology being used to control the microbial spoilage of foods and beverages. Adverse sensory changes, commonly characterized as “lightstruck”, can occur in beers when exposed to the UV portion of PL due to the formation of 3-methylbut-2-ene-1-thiol (3-MBT) upon the photodegradation of iso-α-acids. This study is the first to investigate the effect of different portions of the PL spectrum on UV-sensitive beers (light-colored blonde ale and dark-colored centennial red ale) using clear and bronze-tinted UV filters. PL treatments with its entire spectrum, including the ultraviolet portion of the spectrum, resulted in up to 4.2 and 2.4 log reductions of L. brevis in the blonde ale and centennial red ale beers, respectively, but also resulted in the formation of 3-MBT and small but significant changes in physicochemical properties including color, bitterness, pH, and total soluble solids. The application of UV filters effectively maintained 3-MBT below the limit of quantification but significantly reduced microbial deactivation to 1.2 and 1.0 log reductions of L. brevis at 8.9 J/cm2 fluence with a clear filter. Further optimization of the filter wavelengths is considered necessary to fully apply PL for beer processing and possibly other light-sensitive foods and beverages.

Some chemical compounds, especially alcohol, sugars, and alkaloids such as hordenine, have been reported as elicitors of different emotional responses. This preliminary study was based on six commercial beers selected according to their fermentation type, with two beers of each type (spontaneous, bottom, and top). Chemometry and sensory analysis were performed for all samples to determine relationships and patterns between chemical composition and emotional responses from consumers. The results showed that sweeter samples were associated with higher perceived liking by consumers and positive emotions, which corresponded to spontaneous fermentation beers. There was high correlation (R = 0.91; R² = 0.83) between hordenine and alcohol content. Beers presenting higher concentrations of both, and higher bitterness, were related to negative emotions. Further studies should be conducted, giving more time for emotional response analysis between beer samples, and comparing alcoholic and non-alcoholic beers with similar styles, to separate the effects of alcohol and hordenine. This preliminary study was a first attempt to associate beer compounds with the emotional responses of consumers using non-invasive biometrics.

Brewers’ spent grains (BSGs) are the most important by-product of the brewing industry and are rich in protein and fiber. However, abundant amounts of BSGs are discarded annually worldwide. This project aimed to employ and compare innovative drying techniques to introduce snacks with protein sources derived from leftover BSGs. This study explored the dehydration kinetics of BSGs and the effect of three different drying methods—oven drying (OD), freeze drying (FD), and vacuum microwave drying (VMD)—on their protein content and functionality. Then, an energy and exergy analysis for the drying methods was given. Accordingly, a snack product (baked chips) using the dehydrated BSGs was developed by a sensory panel study to assess consumer acceptability of the final products. It was found that the VMD process took less drying time (48 min) compared to OD (50 min), with higher effectiveness as a drying process. VMD-treated BSG also showed moderate protein functionality and the highest overall acceptability when used in baked chips. Thus, VMD might be used as a sustainable drying technology for thermal treatment and valorization of BSG. In addition to having implications for dietary health, findings can help improve the economy of the breweries and other industries that deal with the processing of grains by valorizing their process waste and contributing to sustainability.

Pulsed light (PL) is a novel, non-thermal technology being used to control the microbial spoilage of foods and beverages. Adverse sensory changes, commonly characterized as “lightstruck”, can occur in beers when exposed to the UV portion of PL due to the formation of 3-methylbut-2-ene-1-thiol (3-MBT) upon the photodegradation of iso-α-acids. This study is the first to investigate the effect of different portions of the PL spectrum on UV-sensitive beers (light-colored blonde ale and dark-colored centennial red ale) using clear and bronze-tinted UV filters. PL treatments with its entire spectrum, including the ultraviolet portion of the spectrum, resulted in up to 4.2 and 2.4 log reductions of L. brevis in the blonde ale and centennial red ale beers, respectively, but also resulted in the formation of 3-MBT and small but significant changes in physicochemical properties including color, bitterness, pH, and total soluble solids. The application of UV filters effectively maintained 3-MBT below the limit of quantification but significantly reduced microbial deactivation to 1.2 and 1.0 log reductions of L. brevis at 8.9 J/cm[sup.2] fluence with a clear filter. Further optimization of the filter wavelengths is considered necessary to fully apply PL for beer processing and possibly other light-sensitive foods and beverages.