Review of the valorization initiatives of brewing and distilling by-products

Beer and spirits are two of the most consumed alcoholic beverages in the world, and their production generates enormous amounts of by-product materials. This ranges from spent grain, spent yeast, spent kieselguhr, trub, carbon dioxide, pot ale, and distilled gin spent botanicals. The present circular economy dynamics and increased awareness on resource use for enhanced sustainable production practices have driven changes and innovations in the management practices and utilization of these by-products. These include food product development, functional food applications, biotechnological applications, and bioactive compounds extraction. As a result, the brewing and distilling sector of the food and drinks industry is beginning to see a shift from conventional uses of by-products such as animal feed to more innovative applications. This review paper therefore explored some of these valorization initiatives and the current state of the art.

Impact of cold plasma processing on major peanut allergens

Cold plasma is emerging as a novel food processing technology, with demonstrated efficacies for microbial inactivation and residual chemical dissipation of food products. Given the technology's multimodal action it has the potential to reduce allergens in foods, however data on the efficacy and mechanisms of action are sparse. This study investigates the efficacy of cold plasma on major peanut allergens (Ara h 1 and Ara h 2). For this purpose, dry, whole peanut (WP) and defatted peanut flour (DPF) were subjected to an atmospheric air discharge using a pin to plate cold plasma reactor for different treatment durations. With increases in plasma exposure, SDS-PAGE analysis revealed reduced protein solubility of the major peanut allergens. Alterations in allergenicity and structure of Ara h 1 and Ara h 2 were examined using ELISA and circular dichroism (CD) spectroscopy. Competitive ELISA with proteins purified from plasma treated WP or DPF revealed reduced antigenicity for both Ara h 1 and Ara h 2. The highest reduction in antigenicity was 65% for Ara h 1 and 66% Ara h 2 when purified from DPF. Results from CD spectroscopy analysis of purified proteins strongly suggests the reduction in antigenicity is due to modifications in the secondary structure of the allergens induced by plasma reactive species. Cold plasma is effective at reducing peanut protein solubility and causes changes in allergen structure leading to reduced antigenicity.

Physical and oxidative stability of functional olive oil-in-water emulsions formulated using olive mill wastewater biophenols and whey proteins

The present paper reports on the use of phenolic extracts from olive mill wastewater (OMW) in model olive oil-in-water (O/W) emulsions to study their effect on their physical and chemical stability. Spray-dried OMW polyphenols were added to a model 20% olive O/W emulsion stabilized with whey protein isolate (WPI) and xanthan gum, in phosphate buffer solution at pH 7. The emulsions were characterised under accelerated storage conditions (40 °C) up to 30 days. Physical stability was evaluated by analysing the creaming rate, mean particle size distribution and mean droplet size, viscosity and rheological properties, while chemical stability was assessed through the measurement of primary and secondary oxidation products. The rheological behaviour and creaming stability of the emulsions were dramatically improved by using xanthan gum, whereas the concentration of WPI and the addition of encapsulated OMW phenolics did not result in a significant improvement of physical stability. The formation of oxidation products was higher when higher concentrations of encapsulated polyphenols were used, indicating a possible binding with the WPI added in the system as a natural emulsifier. This paper might help in solving the issue of using the olive mill wastewater from olive processing in formulating functional food products with high antioxidant activity and improved health properties.

Structure elucidation of ACE-inhibitory and antithrombotic peptides isolated from mackerel skin gelatine hydrolysates

BACKGROUND

The fish-processing industry generates significant amounts of waste and by-products that are usually discarded. This study investigated the preparation of bioactive gelatine peptides from fish skin. Gelatine was extracted from mackerel (Scomber scombrus) skin and hydrolysed by pepsin for 1, 2, 6 and 24 h. All hydrolysates were screened for antioxidant, ACE-inhibitory and antithrombotic activities.

RESULTS

Gelatine peptides obtained after 24 h of hydrolysis exhibited the highest antioxidant activity (DPPH reduction ∼80%, FRAP ∼130 µmol Trolox equivalent L(-1) ). These hydrolysates had high ACE-inhibitory activity (>70%) and were able to significantly (P < 0.05) inhibit platelet aggregation by about 30%, corresponding to moderate antithrombotic activity.

CONCLUSION

The bioactive properties were mainly due to the presence of low-molecular-weight peptides of 337 and 423 Da.

Simultaneous determination of sulphoraphane and sulphoraphane nitrile in Brassica vegetables using ultra-performance liquid chromatography with tandem mass spectrometry

INTRODUCTION

Several analytical methods exist for the determination of sulphoraphane or sulphoraphane nitrile from biological matrices and plant extracts. However, no UPLC-MS/MS method exists for the simultaneous detection of both.

OBJECTIVE

To develop and validate an UPLC-MS/MS method for the simultaneous analysis of sulphoraphane and sulphoraphane nitrile from Brassica oleracea L. ssp. italica

METHODS

This method was developed utilising an Acquity BEH C8 column with gradient elution combined with tandem mass spectrometry, using positive electrospray ionisation in multiple reaction monitoring mode.

RESULTS

The retention times for sulphoraphane and sulphoraphane nitrile were 0.4 and 0.6 min respectively, and total run time was 3 min. The method was validated for linearity, sensitivity, precision, accuracy, matrix effects and recovery. The method was employed to determine glucoraphanin hydrolysis products in broccoli and the predominant product was found to vary depending on the variety tested. It was also applied to the accurate determination of sulphoraphane and sulphoraphane nitrile in broccoli samples hydrolysed under different conditions. It was observed that the formation of sulphoraphane and sulphoraphane nitrile was influenced by the temperature of the reaction.

CONCLUSION

The validated UPLC-MS/MS method for simultaneous detection of sulphoraphane and sulphoraphane nitrile was shown to be applicable to broccoli plants and is expected to be applicable to other cruciferous sources.

The effect of delactosed whey permeate on phytochemical content of canned tomatoes

The effect of delactosed whey permeate (DWP) treatment on antioxidant and phyto-chemical components of canned Irish plum tomatoes were investigated. Tomatoes were sterilised for 5 min (F(0)) at 120 °C and stored for 6 months. The DWP treatment retained significantly (p<0.05) higher levels of ascorbic acid and lycopene of tomatoes. The antioxidant activity of DWP treated tomatoes was higher (7%) than the control at the end of storage. The firmness in DWP-treated fruits was around 40% higher than that in control. All the parameters decreased significantly (p<0.05) during storage except lycopene and total phenols. Lycopene content showed no significant change and total phenols increased during storage. The changes in ascorbic acid, antioxidant activity and texture were fitted well to Weibull kinetic models with high coefficients of determination (R(2)) and low RMSE (root mean sum of squared error). The results clearly indicate that DWP enhanced the retention of antioxidant compounds in tomatoes during storage.

Optimization of ultrasound assisted extraction of antioxidant compounds from marjoram (Origanum majorana L.) using response surface methodology

The present study optimized the ultrasound assisted extraction (UAE) conditions to maximize the antioxidant activity [Ferric ion Reducing Antioxidant Power (FRAP)], total phenol content (TP) and content of individual polyphenols of extracts from marjoram. Optimal conditions with regard to amplitude of sonication (24.4-61.0 μm) and extraction temperature (15-35 °C) and extraction time (5-15 min) were identified using response surface methodology (RSM). The results showed that the combined treatment conditions of 61 μm, 35 °C and 15 min were optimal for maximizing TP, FRAP, rosmarinic acid, luteolin-7-O-glucoside, apigenin-7-O-glucoside, caffeic acid, carnosic acid and carnosol values of the extracts. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E%) ranging from 0.45% to 1.55%. The extraction yields of the optimal UAE were significantly (p < 0.05) higher than solid/liquid extracts. Predicted models were highly significant (p < 0.05) for all the parameters studied with high regression coefficients (R(2)) ranging from 0.58 to 0.989.

Optimization of application of delactosed whey permeate treatment to extend the shelf life of fresh-cut tomato using response surface methodology

Optimization of delactosed whey permeate (DWP) treatment for fresh-cut tomato was accomplished by evaluating different quality, nutritional and microbial markers. Response surface methodology was applied to obtain polynomial model equations. DWP concentration (0-5%) and storage (0-10 days) were used as independent factors in order to optimize the process. The analyses showed that increases in DWP concentration extended the quality of the fresh-cut tomato significantly (p<0.05) by maintaining texture and antioxidant activity (FRAP) and controlling the spoilage during the storage. The total aerobic counts and yeast and molds were reduced by ∼1.5 log cfu/g and ∼1.0 log cfu/g respectively after 10 days of storage treated with 3% DWP. Ascorbic acid and lycopene were retained best within the range of 3 to 5% of DWP treatment. However, concentrations>3% were scored unacceptable by the sensory panel due to perceived off-odors. Predicted models were highly significant (p<0.05) for all the markers studied in fresh-cut tomato with high regression coefficients (R2) ranging from 0.79 to 0.99. The study recommends the use of DWP at a concentration of 3% to extend the shelf life of fresh-cut tomato by preserving its quality and antioxidant properties during storage.

Application of response surface methodology to optimize pressurized liquid extraction of antioxidant compounds from sage (Salvia officinalis L.), basil (Ocimum basilicum L.) and thyme (Thymus vulgaris L.)

The present study optimized pressurized liquid extraction (PLE) conditions using Dionex ASE® 200, USA to maximize the antioxidant activity [Ferric ion Reducing Antioxidant Power (FRAP)] and total polyphenol content (TP) of the extracts from three spices of Lamiaceae family (sage, basil and thyme). Optimal conditions with regard to extraction temperature (66-129 °C) and solvent concentration (32-88% methanol) were identified using response surface methodology (RSM). For all three spices, results showed that 129 °C was the optimum temperature with regard to antioxidant activity. Optimal methanol concentrations with respect to the antioxidant activity of sage and basil extracts were 58% and 60% respectively. Thyme showed a different trend with regard to methanol concentration and was optimally extracted at 33%. Antioxidant activity yields of the optimal PLE were significantly (p < 0.05) higher than solid/liquid extracts. Predicted models were highly significant (p < 0.05) for both total phenol (TP) and FRAP values in all the spices with high regression coefficients (R(2)) ranging from 0.651 to 0.999.

Characterization of phenolic composition in Lamiaceae spices by LC-ESI-MS/MS

A total of 38 phenolic compounds in the solid/liquid extracts of five Lamiaceae spices, rosemary, oregano, sage, basil, and thyme, were identified in the present study using LC-ESI-MS/MS. These compounds were distributed in four major categories, namely, hydroxycinnamic acid derivatives, hydroxybenzoic acid derivatives, flavonoids, and phenolic terpenes. Among them, the category of flavonoids was the largest, with 17 compounds. Identification of the phenolic compounds was carried out by comparing retention times and mass spectra with those of authentic standards. If standards were unavailable, phenolic compounds were identified on the basis of accurate mass of pseudomolecular [M - H](-) ions and tandem mass spectrometry (MS/MS) data. The results of accurate mass measurements fit well with the elemental composition of the compounds. The diagnostic fragmentation patterns of the compounds during collision-induced dissociation (CID) elucidated the structural information of the compounds analyzed.

Use of Fourier transform infrared spectroscopy and chemometric data analysis to evaluate damage and age in mushrooms (Agaricus bisporus) grown in Ireland

The aim of this research was to investigate whether the chemical changes induced by mechanical damage and aging of mushrooms can be (a) detected in the midinfrared absorption region and (b) identified using chemometric data analysis. Mushrooms grown under controlled conditions were bruise-damaged by vibration to simulate damage during normal transportation. Damaged and nondamaged mushrooms were stored for up to 7 days postharvest. Principal component analysis of Fourier transform infrared (FTIR) spectra showed evidence that physical damage had an effect on the tissue structure and the aging process. Random forest classification models were used to predict damage in mushrooms producing models with error rates of 5.9 and 9.8% with specific wavenumbers identified as important variables for identifying damage, and partial least-squares (PLS) models were developed producing models with low levels of misclassification. Modeling postharvest age in mushrooms using random forests and PLS resulted in high error rates and misclassification; however, random forest models had the ability to correctly classify 82% of day zero samples, which may be a useful tool in discriminating between "fresh" and old mushrooms. This study highlights the usefulness of FTIR spectroscopy coupled with chemometric data analysis in particular for evaluating damage in mushrooms and with the possibility of developing a monitoring system for damaged mushrooms using the FTIR "fingerprint" region.

Antimicrobial activity of plant essential oils using food model media: efficacy, synergistic potential and interactions with food components

The aim of this study was to optimise the antimicrobial efficacy of plant essential oils (EOs) for control of Listeria spp. and spoilage bacteria using food model media based on lettuce, meat and milk. The EOs evaluated were lemon balm, marjoram, oregano and thyme and their minimum inhibitory concentrations (MIC) were determined against Enterobacter spp., Listeria spp., Lactobacillus spp., and Pseudomonas spp. using the agar dilution method and/or the absorbance based microplate assay. MICs were significantly lower in lettuce and beef media than in TSB. Listeria strains were more sensitive than spoilage bacteria, and oregano and thyme were the most active EOs. EO combinations were investigated using the checkerboard method and Oregano combined with thyme had additive effects against spoilage organisms. Combining lemon balm with thyme yielded additive activity against Listeria strains. The effect of simple sugars and pH on antimicrobial efficacy of oregano and thyme was assessed in a beef extract and tomato serum model media. EOs retained greater efficacy at pH 5 and 2.32% sugar, but sugar concentrations above 5% did not negatively impact EO efficacy. In addition to proven antimicrobial efficacy, careful selection and investigation of EOs appropriate to the sensory profile of foods and composition of the food system is required. This work shows that EOs might be more effective against food-borne pathogens and spoilage bacteria when applied to foods containing a high protein level at acidic pH, as well as moderate levels of simple sugars.

Efficacy of plant essential oils against foodborne pathogens and spoilage bacteria associated with ready-to-eat vegetables: antimicrobial and sensory screening

The objectives of this study were to evaluate the antimicrobial activity of plant essential oils (EOs) against foodborne pathogens and key spoilage bacteria pertinent to ready-to-eat vegetables and to screen the selected EOs for sensory acceptability. The EOs basil, caraway, fennel, lemon balm, marjoram, nutmeg, oregano, parsley, rosemary, sage, and thyme were evaluated. The bacteria evaluated were Listeria spp., Staphylococcus aureus, Lactobacillus spp., Bacillus cereus, Salmonella, Enterobacter spp., Escherichia coli, and Pseudomonas spp. Quantitative antimicrobial analyses were performed using an absorbance-based microplate assay. Efficacy was compared using MIC, the half maximum inhibitory concentration, and the increase in lag phase. Generally, gram-positive bacteria were more sensitive to EOs than were gram-negative bacteria, and Listeria monocytogenes strains were among the most sensitive. Of the spoilage organisms, Pseudomonas spp. were the most resistant. Oregano and thyme EOs had the highest activity against all the tested bacteria. Marjoram and basil EOs had selectively high activity against B. cereus, Enterobacter aerogenes, E. coli, and Salmonella, and lemon balm and sage EOs had adequate activity against L. monocytogenes and S. aureus. Within bacterial species, EO efficacy was dependent on strain and in some cases the origin of the strain. On a carrot model product, basil, lemon balm, marjoram, oregano, and thyme EOs were deemed organoleptically acceptable, but only oregano and marjoram EOs were deemed acceptable for lettuce. Selected EOs may be useful as natural and safe additives for promoting the safety and quality of ready-to-eat vegetables.

Simultaneous modelling of the thermal degradation kinetics of pectin methylesterase in lettuce (Lactuca sativa L.) and carrot (Daucus carota L.) extracts: analysis of seasonal variation and tissue type

The thermal degradation kinetics of pectin methylesterase (PME) from carrot and lettuce were studied. Fresh extracts were exposed to temperatures from 55 to 70 degrees C until the enzyme was inactivated. A model based on the presence of two forms of the enzyme, one active and one non-active, is proposed. The natural variability of the PME activity was taken into the model in the form of normally distributed random effects. The common model parameters obtained (cleavage constant (0.0395+/-0.0062 s(-1)), degradation constant (0.556+/-0.112 s(-1)), cleavage energy of activation (469+/-23 kJ mol(-1)) and degradation energy of activation (488+/-18 kJ mol(-1))) show that the PME degradation kinetics of the two vegetables can be explained with a single set of parameters.

Effect of heat shock on browning-related enzymes in minimally processed iceberg lettuce and crude extracts

The effects of heat shock on PPO and POD activity in minimally processed Iceberg lettuce was examined during storage (10 days). The results were compared with the effect of temperature on crude extracts of these enzymes (in vitro analysis). Fresh-cut lettuce washed at 50 degrees C showed significantly lower PPO and POD activity throughout storage than lettuce washed at 4 degrees C and 25 degrees C. These results were consistent with a sensory analysis in which the panellists found the lowest browning scores in those samples treated at 50 degrees C. When PPO and POD were analysed in vitro, the samples treated at 50 degrees C showed a rapid loss of POD activity and a similar but slower loss of PPO activity in all tissues, while incubation at 4 degrees C and 25 degrees C showed no significant loss of activity. While heat shock did not lead to significant loss of activity it did repress the synthesis of PPO and POD during storage.