Why was the work done: The deterioration of the flavour of fresh beer is challenging for the brewing industry. Despite extensive research on flavour instability, the focus has centred on a limited set of parameters, rather than taking a broader approach. How was the work done: in this study, the intent was to produce a flavour stable beer. Using a low kilning temperature, malt of low staling potential was used in combination with best brewing practice to produce three batches of unpasteurised top fermented pale beers at a pilot scale. Forty-three markers were analysed in the fresh and aged beers (30°C for 15, 30, 60 and 90 days). Staleness was evaluated by a trained sensory panel and multivariate data analysis was used to explore how the markers contribute to staleness. What are the main findings: Repeatability was achieved between replicate brews and, subsequently, staling. Polyphenols, haze, total reactive antioxidant potential (TRAP), iso-α-acids, colour, furfural, 2-methylpropanal and 2-methylbutanal showed a strong correlation with staleness. Staleness doubled after 60 days of storage at 30°C, despite volatile aldehydes remaining below their sensory thresholds, implying a synergistic effect of carbonyls contributing to staleness. A Partial Least Square (PLS) model was established, modelling the sensory staleness from 2-methylpropanal, furfural, TRAP and the trans-/cis-iso-α-acids ratio. Why is the work important: The staling phenomena could be reproduced in beers from parallel brewing trials with only minor variations. The four parameters in PLS modelling indicate that beer staling involves a combination of oxidative and non-oxidative pathways.

Mashing is a decisive brewing step, affecting wort quality. Critical mashing parameters include time, temperature, pH, mash density and oxygen uptake. While the pH-dependent biochemical changes during mashing have been researched, the oxidative processes remain unclear. This work explores the impact of pH conditions during mashing on the biochemical composition and oxidative properties of wort. In laboratory trials, mashing was conducted at different mashing-in pH (4.5, 5.0, 5.2, 5.4, 6.0). The sweet worts were analyzed for extract, fermentable sugars, limit dextrins, amino acids, soluble proteins, polyphenols, color, aldehydes, transition metals, reducing potential, and rate of radical formation. Differences were found in enzymatic activities (particularly proteolysis), color, aldehydes, transition metal ions, the rate of radical formation and the rate of oxygen consumption. Notably, when adjusting the pH at mashing-in, the obtained wort tends to gravitate toward the pH of the unadjusted wort, underscoring its buffering capacity. This was reflected by similar properties of the produced worts, indicating pH playing a lesser role during mashing compared to time/temperature. However, under extreme acidified conditions (pH 4.5 at mashing-in), the produced wort markedly deviates. An intriguing negative correlation between the reducing potential and the content of transition metal ions with the rate of radical formation is discussed.

Understanding the contribution of raw materials to the quality of the final product is crucial for the food industry. In the brewing process, malt delivers various compounds that compromise the flavour stability of beer, including staling aldehydes and their precursors. The primary aim of this study was to investigate the evolution of staling aldehydes and their cysteinylated counterparts throughout industrial scale pale malt production. The second objective was to study the extent to which process related gradients (e.g., temperature, moisture) may contribute to the differential formation of free and bound state aldehydes. Samples were collected from two industrial scale, pale lager malt production processes as a function of process time (germination, kilning, and cooling) and the position of the kernals in the grain bed (bottom, middle and top layers) during kilning. The levels of free and cysteinylated aldehydes were determined. The results show that the initial stage of germination is accompanied by enzymatic fatty acid oxidation as reflected by the formation of hexanal and trans-2-nonenal. Drying at elevated temperature (at a critical moisture content of 6-9%) results in the intensified formation of cysteinylated Strecker aldehydes and furfural. Moreover, a rapid increase in the formation of (cysteinylated) Strecker aldehydes furfural and trans-2-nonenal continued through kilning. A clear effect of temperature and moisture gradients was observed on the formation of aldehydes and it is concluded that exposure to heat load plays a critical role in the development of cysteinylated aldehydes during malt production. This publication is dedicated to the memory of Professor Luc De Cooman.

Flavour instability of beer is a concern for brewers and has been investigated over many decades. Despite advancements in the characterisation of changes during the ageing process of pale lager beers (PLB), research on the flavour instability of non-alcoholic beer (NAB) - a beer style becoming increasingly prevalent on the market - is lacking. This study characterises the main chemical-analytical changes during a forced ageing process (90 days at 30°C) of seven commercially available NAB and compares the findings to the aged seven PLB counterparts. The major differences from ageing were increased concentrations of aldehydes and decreased levels of glutamine and esters, which occurred to the same extent for both beer styles. However, trans-iso-α-acids underwent a greater decrease in aged NAB, likely due to the lower pH of this style. Furthermore, correlations between ageing parameters in aged and fresh beers, previously found in PLB (Strecker aldehydes and corresponding amino acids, relative decrease of trans-iso-α-acids and pH) are confirmed and were also valid in NAB. Interestingly, sensory analysis revealed that aged NAB showed lower overall ageing scores, compared to aged PLB. This might be explained by differences in the formation of aldehydes causing worty off-flavours during ageing. In summary, this study provides a detailed overview of the ageing process of non-alcoholic beers in comparison with pale lager beers, which could help brewers to develop more flavour stable beers. © 2022 The Institute of Brewing & Distilling.

To meet consumer demand and remain competitive, brewers attempt to broaden their product range with new, innovative flavors. One way to achieve this is by (partially) replacing barley malt with less common adjuncts, such as the ancient wheat varieties einkorn, emmer, spelt, and khorasan; the pseudocereals quinoa, amaranth, and buckwheat; or the alternative cereals sorghum, teff, and tritordeum. The physical (grain size and thousand kernel weight), chemical (starch, protein, fat, beta-glucan, and water content), and physicochemical (gelatinization temperature, amylase content) properties of these alternative cereals and pseudocereals were determined, as well as their aldehyde concentrations and flavor profiles. The starch content ranged from 45.2 +/- 1.2 %dm for einkorn to 75.5 +/- 0.6 %dm for teff. The protein content ranged from 10.6 +/- 0.0 %dm for barley malt to 18.4 +/- 0.6 %dm for khorasan. Major differences were found for the diastatic power, with quinoa having the lowest (6 +/- 4 degrees WK) and spelt the highest (277 +/- 19 degrees WK) value. Most alternative cereals and pseudocereals had an onset gelatinization temperature <63 degrees C, making them suitable for common brewing practices. This was not the case for quinoa, amaranth, teff, and sorghum, which had a gelatinization temperature >= 64 degrees C. Aldehyde concentrations were significantly lower in alternative cereals and pseudocereals, compared to malted barley.

Despite decades of extensive research, beer flavour instability remains a challenge for both brewing and malting industries. Malt impacts the brewing process as well as the quality of the final beer. It also affects the stability of beer flavour, as it delivers to the brewing process various compounds with the potential to compromise the desired flavour characteristics of beer. These include staling aldehydes and their precursors, such as amino acids, reducing sugars, α -dicarbonyls and bound-state aldehydes. In general, the content of these compounds depends on barley variety and quality, the malting regime and final malt quality. Malt that represents a low potential for beer staling, i.e . that has low values of Kolbach Index, heat load, colour, LOX activity, Strecker aldehydes, transition metal ions and high antioxidative activity, leads to beer with enhanced flavour stability. However, the con-sistent production of malt with the desired quality remains challenging. Approaches to achieve this include adjustment of steeping and germination conditions, allowing control of grain modification and thus, the reservoir of aldehydes precursors. Also, the application of alternative kilning technologies may reduce the applied heat load, responsible for the formation of stal- ing aldehydes and triggering development of the oxidising free radical species. This review provides an evaluation of current knowledge on the contribution of the malting process and malt quality to the formation of beer staling aldehydes. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling. degradation (Strecker degradation of amino acids in a strict sense, Strecker-like reactions, direct Strecker aldehyde formation from Amadori compounds, direct oxidation of amino acids); (4) oxidative degradation of isohumulones; (5) aldol condensation of short chain aldehydes; (6) oxidation of higher alcohols; (7) secondary oxidation of long chain aldehydes and (8) secretion by fermenting yeast.

In this study, the major differences between commercial pale lager beers (PLB) and their non-alcoholic (NAB) counterparts were characterised by chemical-analytical and sensory analysis. Chemical-analytical profiling was performed using standard brewery analyses in addition to gas and liquid chromatography for quantifying volatile and non-volatile compounds. NAB differed in analytical composition from the PLB, in sugar, aroma, and amino acid profiles. Generally, the PLB contained higher levels of volatile aroma constituents (in particular, significantly higher levels of 2-methylbutan-1-ol, 3-methylbutan-1-ol, ethyl acetate, ethyl hexanoate and ethyl octanoate), specific amino acids (including cysteine, glutamine and alanine), sulphite, glycerol and proteins. NAB show significantly higher concentrations of fermentable sugars (maltose, glucose, fructose and maltotriose), as well as higher levels of amino acids (including threonine, serine and asparagine) and trans-2-nonenal. The PLB was similar in analytical composition, whereas the NAB could be discriminated into two clusters, reflecting different sugar profiles, reflecting the production technology. Organoleptic assessment described the flavour of the NAB as 'worty', 'sweet' and 'watery', while the PLB scored higher in 'bitterness intensity' and 'fullness'. Interestingly, those NAB where the analytical profile differed the most from their PLB counterparts exhibited the largest differences in sensory properties. Furthermore, this study suggests synergistic and/or antagonistic effects between groups of chemical compounds which may explain the flavour differences. For instance, high sugar levels suppress the perception of bitterness, whereas sugars, aldehydes and esters impact on the worty flavour of NAB. © 2021 The Institute of Brewing & Distilling

Different microalgal species are a sustainable, alternative source of omega-3 long chain poly-unsaturated fatty acids (n-3 LC-PUFA) and can be incorporated into the food chain. However, the impact of microalgal species, photoautotrophic versus heterotrophic, on the enrichment of food products with n-3 LC-PUFA and their oxidative stability has never been studied before. This study provides greater insight into the impact of the microalgal species in enriched tomato puree. Therefore, four microalgal species (three photoautotrophic: Isochrysis, Nannochloropsis and Phaeodactylum and one heterotrophic: Schizochytrium) were compared to each other and analyzed for their amount of n-3 LC-PUFA, antioxidants, free fatty acids and lipid oxidation products. Photoautotrophic microalgal species were able to create a tomato puree rich in n-3 LC-PUFA without compromising the oxidative stability. On the other hand, tomato puree, although rich in antioxidants, was not able to keep the n-3 LC-PUFA in purees supplemented with Schizochytrium biomass oxidatively stable.

The impact of pod storage (PS) and roasting temperature (RT) on the quality parameters and the sensory profiles of dark chocolates were evaluated. Dark chocolates (70%) from ten liquors of different PS and RT combinations as well as six liquors of different origins (Ecuador, Ghana, Ivory Coast, Madagascar, Venezuela and Vietnam) with variable genetic groups were produced under identical conditions and compared. To a greater extent, the range of chocolate quality attributes underscored the generally minimal effects of PS, RT and origin of liquor on the processing conditions. Although with a few exceptions, generally, chocolate acidity (pH and TA) decreased with increasing PS and vice versa in the case of RT. Furthermore, results from a balanced incomplete block design (BIBD) involving a 16-member expert panel also revealed the impact of the applied treatments (PS and RT) on the final flavor profiles of the chocolates irrespective of the origin or genetic groups of the cocoa beans. The same was confirmed when instrumental aroma results were correlated with the sensory data using partial least squares (PLS) regression models. Thus, this study demonstrates the possibility of creating diverse flavor profiles (even towards 'fine' flavor) from 'bulk' cocoa beans through an optimized combination of PS and RT. The findings are therefore expected to challenge the status-quo, especially in the way 'bulk' cocoa is currently processed and consequently priced, thereby, possibly fostering a win-win situation between cocoa producers and industries.

Summary Vegetable purees can be interesting food products to enrich with omega‐3 long‐chain polyunsaturated fatty acids (n‐3‐ LC ‐ PUFA ), since they are important carriers of nutrients and fibres and essential in a healthy diet. Due to their large number of double bounds, n‐3‐ LC ‐ PUFA are highly susceptible to lipid oxidation. Different vegetable purees, containing different types and amounts of endogenous antioxidants, may possibly show differences in oxidative stability. This study contributes to obtain more insight into the impact of the type of vegetable (broccoli, carrot or tomato) on the oxidative stability of purees enriched with heterotrophic ( Schizochytrium ) n‐3‐ LC ‐ PUFA ‐rich microalgal biomass. Therefore, different vegetable purees enriched with microalgae were compared with each other and analysed for their amount lipid oxidation products and antioxidants. Broccoli and tomato puree enriched with Schizochytrium showed a higher oxidative stability compared to enriched carrot puree. However, all of these Schizochytrium ‐enriched purees were prone to oxidation.

Aldehydes originating from malt play an important role in beer flavour deterioration. In order to better understand the influence of malting process on beer staling, it is necessary to acquire a reliable analytical methodology for determination of beer staling aldehydes in malt. Therefore, the aim of this study was to evaluate extraction parameters, which allow quantification of beer staling aldehydes present in pale malts. The method was validated with respect to linearity (R > 0.9988), limit of detection (0.28 - 0.99 mu g/L), limit of quantification (0.92 - 3.31 mu g/L), accuracy (+/- 5%), repeatability (1.3 - 5.3%) and intermediate precision (>20%). The following parameters of sample preparation were evaluated: sample amount, extraction time and temperature, ultrasonication time and oxygen level. Consequently, the best extraction conditions were successfully applied on pale malts. After extraction, the samples were analysed by headspace solid-phase microextraction (HS-SPME) with on fibre carbonyl derivatisation followed by gas chromatography and mass spectrometry (GC-MS). In addition, the salting-out effect during HS-SPME was studied. The method application allowed to identify significant differences (p <= 0.05) in the levels of aldehydes among various industrial scale, pale malts. The optimised method could give the information on the aldehyde content introduced into the brewing process and its potential contribution to the overall beer quality. (C) 2019 Elsevier B.V. All rights reserved.

Microalgae are a valuable alternative source of n-3 LC-PUFA and have already proven their potential in different food products. However, enrichment of food products with n-3 LC-PUFA implies an increased sensitivity to lipid oxidation. Numerous analytical techniques have already been developed to determine and follow lipid oxidation. Photoautotrophic microalgae often contain, besides n-3 LC-PUFA, other compounds like carotenoids and chlorophylls. These colored compounds may interfere with the standard analytical techniques. This study contributes to optimize a simple and low-cost method to measure the degree of primary lipid oxidation in food products enriched with photoautotrophic microalgae. The standard iodometric titration and three spectrophotometric methods (FOX, IDF, and CD & CT) were investigated. The FOX method was selected as the preferable method, although interference due to the presence of metal ions could occur. This could partially be solved by a supplemental step with TPP addition. However, as this additional step did not change the trend in oxidative values during storage, it was suggested to normalize the values of the FOX method to week zero to investigate the trend of oxidation during storage of products enriched with photoautotrophic microalgae.

Overall ageing scores (OAS) are used by expert beer tasters to distinguish between the different aromas and tastes, in order to assess the sensorial quality and flavour stability of beer. Flavour instability is an important issue to brewers owing to the increased global demand for beer and the difficulties of controlling beer quality in remote locations when exported. In this paper, the idea was developed and a model constructed that is able to estimate the OAS as a function of temperature and time. The study highlights not only the exponential impact of temperature on lager quality, but also the importance of the time of exposure (nonlinear effect). Further, a hypothetical case study was performed in which the OAS was determined of a lager exposed to the temperature conditions in an important Belgian beer import market. The results indicate that in cities with a mild climate (e.g. UK and Germany), lager beer will suffer quality degradation to a limited extent. Temperature in warm climate cities (e.g. Italy and China) will significantly reduce the shelf life of lager beer in a short time frame, stressing the importance of flavour quality and stability. The model can be used in both industry and research when developing commercial decisions. (C) 2019 The Institute of Brewing & Distilling

The unique impact of roasting conditions on the aroma quality of cocoa beans has been demonstrated in many studies. However, information on the additional impact of pod storage (PS) and its combined effect with roasting temperature (RT) is unknown. Hence, this study sought to elucidate the collective contribution of these post-harvest/process parameters on the aroma profiles of cocoa liquors produced from Forastero cocoa beans. The beans had been subjected to different treatments following a 3 × 4 full factorial experiment, consisting of PS (0, 3, 7 days) and RT (100, 120, 140, 160 °C). Statistical analysis of the results from HS-SPME-GC-MS revealed significant (p < .05) impact of both PS and RT as well as their interaction effects on the ten groups of volatiles (acids, alcohols, esters, terpenes, aldehydes, ketones, pyrazines, furans, pyrroles and others) and their overall aroma concentration. An exception was however noted for aldehydes, where the total concentration was only significantly (p < .05) influenced by the individual effects of PS and RT. A subsequent clustering of the liquors, first on the basis of all identified volatiles, then, on the basis of the odor-active volatiles, also revealed similar pattern where liquors with high RT's possessed more volatiles with higher concentrations and vice versa. More so, it seemed that no or very minimal PS treatment was necessary for preserving more aromatic volatiles with typically fruity, floral or spicy flavor notes, whereas, for liquors with volatiles exhibiting more cocoa, chocolate, nutty and roasted flavor notes, prolonged PS (> 3 days) treatment was required. These findings are expected to challenge the status-quo, specifically in the conventional ways through which the aroma potential of 'bulk' cocoa may be steered. On the one hand, the idea of manipulating PS treatment and roasting conditions may indeed consolidate the possibility of creating diverse and/or distinct aroma profiles from the same 'bulk' cocoa beans, whereas, on the other hand, it raises the question whether the Ghanaian cocoa beans - being described as 'bulk' cocoa - could be a consequence of prolonged pod storage treatment.

The use of alternative equipment for chocolate production is gaining attention in recent times in many countries. This is due to the lower cost of investment and maintenance, multi-functionality, and lower throughput. This study was conducted to investigate the applicability of two of such equipment; melanger and Stephan mixer. In the first set-up, the possibility of refining chocolate with the melanger in comparison with the conventional 3-roll refiner was explored. Whereas in the second set-up, the applicability of the Stephan mixer (aided with a vacuum pump) for a conching-like application was also investigated. From each set-up, 70% dark chocolates produced through various alternative means were then evaluated on the basis of their flavor profiles. Specific groups of volatiles such as aldehydes, ketones, terpenes and terpenoids, showed significant (p < 0.05) differences due to the different refining techniques applied. However, this effect was not reflected in terms of the overall volatile concentrations of these chocolates. For chocolates which were conched with Stephan mixer, the decreasing effect of vacuum duration and its interaction with dry conching temperature on the total volatile concentration also proved significant (p < 0.05). Finally, an agglomerative hierarchical clustering of all chocolates on the basis of their aroma volatiles revealed three distinct clusters. Nonetheless, a 112—member consumer preference testing showed statistically similar (p > 0.05) preference for these representative chocolates from the clusters. These findings stimulate various practical application possibilities for tuning chocolate flavor through alternative processing for both industries and various artisans worldwide.

BACKGROUND Beer flavor stability is important to brewers as a result of the increased global demand for beer. Increasing export leads to prolonged periods of transportation and storage and causes fresh flavor deterioration. Therefore, the present study examined the effect of different temperatures in combination with vibrations on beer quality. Beer was exposed to vibrations (50 Hz, 15 m s(-2), simulating transport) at 5, 30 and 45 degrees C for 22, 38 and 90 h and (for half the samples) aged for 60 days at 30 degrees C. RESULTS The results obtained indicated decreased oxygen concentrations as a result of an elevated temperature and vibrations. There was no effect (P > 0.05) on color and a limited effect of temperature and vibrations on iso-alpha-acids. The parameters temperature and vibrations have a significant influence (P < 0.05) on aldehyde concentrations, namely total aldehydes, and especially '2-methylpropanal', '2-methylbutanal' and 'furfural'. CONCLUSION The impact of vibrations on the aldehydes concentrations was substantial when subjected to an elevated temperature. Furthermore, a forced aging test of shorter duration than traditional methods might be developed. (c) 2018 Society of Chemical Industry

This study describes the possibilities of valorising a waste stream that originates from apple wood by mapping the reducing capacity and phenolic profile from extracts derived from apple tree (Malus domestica). This study evaluated the efficiency of warm solvent extraction (WSE) and ultrasound-assisted extraction (UAE) techniques for extracting antioxidant phenolic compounds from the bark and core wood of an apple tree cultivated in the north-eastern part of Belgium. Furthermore, the influence of the pre-treatment technique, namely, fresh, oven-dried, and freeze-dried samples, respectively, on the yield of polyphenols was studied. Fresh bark extract obtained by UAE—the most efficient extraction technique—employing acetone 60% v/v contains the highest levels of phenolic compounds as well as the highest antioxidant activity. High-performance liquid chromatographic analysis shows that phloridzin is the major compound of the identified polyphenol markers present in bark and core wood extracts. Based on the obtained results, it may be possible to produce a polyphenolic extract from apple wood at an industrial scale without extensive costs or altering the antioxidant properties. This study reveals the potential of apple tree wood residues valorisation through the recovery of phenolic compounds for food, pharmaceutical, and cosmetic applications.

Conventional dark chocolate production methods that are applied in the industry consist of several steps, which require equipment with big investment costs. There are however few cost-effective alternatives suggested for small-scale production. Meanwhile, knowledge on these alternative equipment/techniques are insufficient to promote miniature production of high quality chocolates, either for research purposes in an industrial context, or for producers in developing countries, where the cost of investing in conventional equipment seems to be an impediment. The aim of this study was two-fold; first, to assess the feasibility of utilizing the ECGC-12SLTA CocoaTown melanger as an alternative to the conventional 3-roll refiner at different settings and fat content. Thereafter, one optimal setting was selected for each equipment for further investigation on the impact of the refining on some quality attributes of the final dark chocolate (70% cocoa). Secondly, the Stephan mixer; being used to mimick a conching-like process, was assessed with respect to two processing factors; the dry conching temperature (60 degrees C, 80 degrees C) and the duration of vacuum pump connection (0, 30, 60 min). The latter was to facilitate adequate moisture removal. The melanger proved to be a suitable alternative to the 3-roll refiner, provided that refining was carried out at moderate/high (ca. 40%) fat content, as is often the case for "high -percentage-cocoa" chocolates. Refining for 180 min with the mini drum at 40% resulted in D (v,0.9) significantly (p < 0.05) lower than when the 3-roll refiner was used. Nonetheless, a comparative advantage of the latter would be its short throughput time (5-10 min). Due to a resultant linear speed gradient of the chocolate mass due to the cylindrical roller stones, a more efficient refining was achieved with the mini drum than with the big drum. More so, refining in excess fat (40%) may have contributed to a more efficient coating of the newly created hydrophilic sugar surfaces, thus, limiting the possibility for moisture-induced agglomeration as may have been the case for the recipe with 27% fat. In spite of trivial difference in moisture content, chocolates manufactured following melanger and 3-roll refining showed significant (p < 0.05) differences in terms of particle size, flow parameters and color. For chocolates that were conched with the Stephan mixer, the vacuum duration had a significant (p < 0.05) impact on moisture content and D (v,0.9). Also, an impact of all factors and their interaction on the Casson yield values of the chocolates was observed. However, these factors proved to be less important in dictating the final viscosities of the chocolates. Among others, it is suggested that the influence of the high fat content of the chocolates may have played a more important role. Although all chocolates exhibited less thixotropic behavior, a direct proportional relationship between the particle surface area and thixotropy was observed. Finally, the interaction effect of both factors also significantly (p < 0.05) influenced the color of the chocolates.

Microalgae have already shown their potential as an alternative source of n-3 LC-PUFA. In this study, 5 different microalgal species (Isochrysis, Nannochloropsis, Phaeodactylum, Porphyridium and Schizochytrium) were added to an acidic model system and screened on their potential use in acidic food matrices. The impact of mechanical and thermal processing on the model systems was studied by analyzing the amount of n-3 LC PUFA, free fatty acids, carotenoids, lipid polymers and the oxidative stability. A (limited) reduction of n-3 LC PUFA was observed. Thermal alterations combined with the presence of free fatty acids seemed to be the causing factor for this decrease. Furthermore, the oxidative stability of model systems enriched with photoautotrophic microalgae was significantly higher than of those enriched with heterotrophic microalgae. It can therefore be concluded that photoautotrophic microalgae low in initial free fatty acid content are a promising source of n-3 LC PUFA in thermally processed acidic food systems.