Influence of transport and storage conditions on beer quality and flavour stability

Vibration Emissions Reduce Boar Sperm Quality via Disrupting Its Metabolism

Artificial insemination (AI) with liquid-preserved semen has recently become common in pig breeding. The semen doses are produced in a centralized manner at the boar stud and then subsequently distributed and transported to sow farms. However, vibration emissions during transportation by logistic vehicles may adversely affect the quality of boar sperm. Therefore, this study aimed to explore the impact of vibration-induced emissions on sperm quality and function under simulated transportation conditions. Each time, ejaculates from all 15 boars were collected and then pooled together to minimize individual variations, and the sample was split using an extender for dilution. Different rotational speeds (0 rpm, 80 rpm, 140 rpm, 200 rpm) were utilized to simulate varying intensities of vibration exposure using an orbital shaker, considering different transportation times (0 h, 3 h, and 6 h). Subsequently, evaluations were conducted regarding sperm motility, plasma membrane integrity, acrosome integrity, mitochondrial function, adenosine triphosphate (ATP) levels, mitochondrial reactive oxygen species (ROS) levels, pH, glycolytic pathway enzyme activities, and capacitation following exposure to vibration emissions. Both vibration time and intensity impact sperm motility, plasma membrane integrity, and acrosomal integrity. Vibration exposure significantly reduced sperm ATP levels, mitochondrial membrane potential, and the levels of mitochondria-encoded proteins (MT-ND1, MT-ND6) (p < 0.05). After vibration emission treatment, the pH value and mitochondrial ROS levels significantly increased (p < 0.05). Inhibition of sperm glycolysis was observed, with reduced activities of hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH), along with decreased lactate levels (p < 0.05). Additionally, sperm tyrosine phosphorylation levels were significantly reduced by vibration emissions compared to the control group (p < 0.05). After the vibration emission treatment, the number of sperm bound to each square millimeter of oviduct explants decreased significantly compared to the control group (p < 0.05). Similarly, compared to the control group, using semen subjected to vibration stress for AI results in significantly reduced pregnancy rates, total born litter size, live-born litter size, and healthy born litter size (p < 0.05).

Effects of tea addition on antioxidant capacity, volatiles, and sensory quality of beer

Green tea has great potential to enhance the quality of beer. In this study, green tea was added at different stages of beer brewing, and evaluated the antioxidant capacity, volatile components, as well as sensory quality. The results showed that the addition of green tea during the start of boiling has great potential for application, and the green tea beer (GTB) had remarkable antioxidant properties (ABTS radical scavenging ability, 8.67 mmol TE/L; DPPH radical scavenging ability, 3.97 mmol TE/L; reducing power, 3.28 mmol TE/L), and an excellent sensory quality (acceptance, 6.09/9). HPLC analysis indicated that the principal phenolics in GTB were catechin and caffeic acid, in addition, the relative amounts of ferulic acid, gallic acid can be used to differentiate between GTB and beer. HS-SPME-GC-MS analyses showed that ethyl caprylate, ethyl nonanoate, ethyl caprate, linalool, and phenethyl alcohol were potentially significant for the aroma profile of GTB.

Multivariate Analysis of the Influence of Microfiltration and Pasteurisation on the Quality of Beer during Its Shelf Life

Gas chromatography-mass spectrometry (GC-MS), physicochemical and microbiological analyses, sensory descriptive evaluation, and multivariate analyses were applied to evaluate the efficiencies of microfiltration and pasteurization processes during the shelf life of beer. Samples of microfiltered and pasteurised beer were divided into fresh and aged groups. A forced ageing process, which consisted of storing fresh samples at 55° C for 6 days in an incubator and then keeping them under ambient conditions prior to analysis, was applied. Physicochemical analysis showed that both microfiltered and pasteurised samples had a slight variation in apparent extract, pH, and bitterness. The samples that underwent heat treatment had lower colour values compared with those that were microfiltered. Chromatographic peak areas of vicinal diketones increased in both fresh and aged samples. The results of the microbiological analysis revealed spoilage lactic acid bacteria (Lactobacillus) and yeasts (Saccharomyces and non-Saccharomyces) in fresh microfiltered samples. In the GC-MS analysis, furfural, considered by many authors as a heat indicator, was detected only in samples that underwent forced ageing and not in samples that were subjected to thermal pasteurisation. Finally, sensory analysis found differences in the organoleptic properties of fresh microfiltered samples compared with the rest of the samples.

Assessment of the Prediction Power of Forced Ageing Methodology on Lager Beer Aldehyde Evolution during Maritime Transportation

The globalisation of the beer market forces brewers to have methodologies that rapidly evaluate the evolution of beer flavour stability. Commonly used forced ageing methods have limitations since temperature and transportation conditions (temperature, vibrations, long-distance travel, and other factors) impact beer quality. This study assessed the prediction power of a forced ageing methodology on the evolution of aldehydes during maritime transportation across four sample groups (maritime transport, storage simulation, and three ageing periods: 7, 21, and 28 days at 37 °C), which differed in their bottle-opening system (either crown cap or ring pull cap). The results revealed that forced ageing up to 28 days could estimate the evolution of phenylacetaldehyde, 3-methylbutanal, 2-methylpropanal, and hexanal during maritime transport. In contrast, the benzaldehyde content was consistently underestimated, on average, 0.8 times lower. In general, the ageing conditions significantly favoured the formation or liberation from a bound state, up to 2.2 times higher, of trans-2-nonenal, acetaldehyde, and 5-hydroximethylfurfural in comparison to the levels registered on exportation simulation beers. Moreover, forced-aged beers with ring pull caps developed quantifiable levels of nonanal and increased phenylacetaldehyde, benzaldehyde, and acetaldehyde content over time. Moreover, thermal stress induced a continuous increase in the extent of beer staling, up to seven times higher, in most samples.

Flavour Stability of a Cold-Stored Unpasteurized Low-Alcohol Beer Produced by Saccharomycodes ludwigii

Low-alcohol beer (LAB) is a growing part of the brewing industry in terms of market volumes and consumer interest. Universities and research centres are making efforts to improve organoleptic profile and flavour stability of the product. One of the main limitations of such products is the stability. These beers must be severely filtered and pasteurized, causing a significant loss of quality in terms of flavour. Herein, flavour stability of an unpasteurized and unfiltered LAB was checked during 120 days of cold storage (4 ± 1 °C). The results showed that the beer remained stable for 120 days for many observed parameters. The alcohol content increased from 0.5 to 0.7% v/v. The beer without oxygen was more stable than that filled with oxygen in the headspace. The results confirmed the possibility to produce an unpasteurized craft LAB by Saccharomycodes ludwigii by the cold chain.

Graphical Abstract

Monitoring the Evolution of the Aroma Profile of Lager Beer in Aluminium Cans and Glass Bottles during the Natural Ageing Process by Means of HS-SPME/GC-MS and Multivariate Analysis

Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS), sensory evaluation, and multivariate analysis were applied to monitor and compare the evolution of the aromatic profile of a lager beer in different types of containers (aluminum cans and glass bottles) during the natural ageing process. Samples were aged naturally for a year in the absence of light with a controlled temperature of around 14 °C +/- 0.5 °C. The sensory evaluation applied was a blind olfactometric triangle test between canned and bottled samples at different periods of aging: fresh, 6 months, and 11 months. The sensory evaluation showed that the panelists were able to differentiate between samples, except for the fresh samples from the brewery. A total of 34 volatile compounds were identified using the HS-SPME/GC-MS technique for both packaging types in this experiment. The application of multivariate analysis to the GC-MS data showed that the samples could not be differentiated according to the type of packaging but could be differentiated by the ageing time. The results showed that the combination of sensory, HS-SPME-GC-MS, and multivariate analysis seemed to be a valuable tool for monitoring and identifying possible changes in the aroma profile of a beer during its shelf life. Furthermore, the results showed that storing beer under optimal conditions helped preserve its quality during its shelf life, regardless of the type of packaging (aluminum can and glass bottle).

An Overview of the Application of Multivariate Analysis to the Evaluation of Beer Sensory Quality and Shelf-Life Stability

Achieving beer quality and stability remains the main challenge for the brewing industry. Despite all the technologies available, to obtain a high-quality product, it is important to know and control every step of the beer production process. Since the process has an impact on the quality and stability of the final product, it is important to create mechanisms that help manage and monitor the beer production and aging processes. Multivariate statistical techniques (chemometrics) can be a very useful tool for this purpose, as they facilitate the extraction and interpretation of information from brewing datasets by managing the connections between different types of data with multiple variables. In addition, chemometrics could help to better understand the process and the quality of the product during its shelf life. This review discusses the basis of beer quality and stability and focuses on how chemometrics can be used to monitor and manage the beer quality parameters during the beer production and aging processes.

Boar Semen Shipping for Artificial Insemination: Current Status and Analysis of Transport Conditions with a Major Focus on Vibration Emissions

In the modern pig reproduction system, artificial insemination (AI) doses are delivered from AI centers to sow farms via logistics vehicles. In this study, six breeding companies in three countries (Brazil, Germany, and the USA) were interviewed about their delivery process. It was found that there is currently no comprehensive monitoring system for the delivery of semen. The entire process “shipping of boar semen” was documented using Business Process Model and Notation (BPMN). Although it is not currently known which vibrations occur at all, it is suspected that vibration emissions affect the quality of boar semen. For this reason, a prototype of a measuring system was developed to calculate a displacement index (Di), representing vibration intensities. Vibrations were analyzed in standardized road trials (n = 120) on several road types (A: smooth asphalt pavement, B: rough asphalt pavement, C: cobblestone, and D: dirt road) with different speeds (30, 60, 90, 120, and 150 km/h). A two-way ANOVA showed significant differences in mean Di, depending on road surface and speed as well as an interaction of both factors (p < 0.001). A field study on a reference delivery from a German AI center to several sow farms indicated that 33% of the observed roads are in good quality and generate only a few vibrations (Di ≤ 1), while 40% are of a moderate quality with interrupted surfaces (Di = 1−1.5). However, 25% of the roads show markedly increased vibrations (Di ≥ 1.5), as a consequence of bad conditions on cobblestones or unpaved roads. Overall, more attention should be paid to factors affecting sperm quality during transport. In the future, an Internet of Things (IoT) based solution could enable complete monitoring of the entire transport process in real time, which could influence the courier’s driving behavior based on road conditions in order to maintain the quality of the transported AI doses.

Research Status and Prospect for Vibration, Noise and Temperature Rise-Based Effect of Food Transport Pumps on the Characteristics of Liquid Foods

In the field of food processing, the processing of liquid foods has always played an important role. Liquid foods have high requirements for the processing environment and equipment. As the core equipment in liquid foods processing, food transport pumps are widely used in liquid foods production, processing and transportation. Most liquid foods are non-Newtonian and vulnerable to vibration, noise, and temperature rise produced by rotary motions of food transport pumps in operation, which can finally affect foods safety. Therefore, this review summarizes the impact of mechanical vibration, noise, and temperature rise on liquid food products, with the aim of ensuring food safety while designing a cleaner, safer and more reliable food transport pumps in the future.

Assessment of Staling Aldehydes in Lager Beer under Maritime Transport and Storage Conditions

Beer flavor stability is greatly influenced by external temperature, vibrations, and longer delivery times. The present study assessed the impact of transport and storage conditions on staling aldehyde evolution in lager beers across five sample groups (fresh, transport, and storage simulation, and their controls), which differed in their bottle opening system (either crown cap or ring pull cap). Maritime transport conditions (45 days of travel, vibrations of 1.7 Hz, and warm temperatures (21-30 °C)) were simulated, together with storage time in a distributor's warehouse (up to 75 days). The results revealed that the concentration of Strecker aldehydes increased more quickly after transport and storage simulation in beer bottles with the ring pull cap opening system, and the contents of 2-methylpropanal and 3-methylbutanal, in particular, were up to three times higher. Benzaldehyde content also increased significantly, by 33% on average, in these samples. Hexanal was only found in beers with a ring pull cap that underwent transport simulation. Further storage after transport simulation significantly reduced the content of 2-methylpropanal, 3-methylbutanal, and hexanal, by 73%, 57%, and 43%, respectively, suggesting the formation of a bound state. 5-hydroxymethylfurfural was continuously increased by 78.5% and 40.5% after the Transport and Transport & Storage simulations, respectively. Transport conditions lead to a slight increase, of 0.6 EBC units, in beer color.

A Comprehensive Evaluation of Flavor Instability of Beer (Part 1): Influence of Release of Bound State Aldehydes

Flavor instability of pale lager beer depends decisively on aroma-active aldehydes from the Maillard reaction, Strecker degradation, and lipid oxidation, which are formed in various oxidative and non-oxidative reactions. Therein, aldehydes can be formed de novo and be released from bound states to a free, aroma-active form during aging. During malting and brewing, proteolysis affects the amount of soluble nitrogen and thus flavor instability in different ways (e.g., precursors for de novo formation and binding agents for bound states). To isolate nitrogen-related aging processes, beers from malts (two barley varieties, three proteolytic malt modifications) were produced on a 50 L scale in part 1 of this study. Sensory analysis revealed increased flavor instability for beers with higher amounts of soluble nitrogen. Especially Strecker aldehydes significantly increased with malt modification. The release of bound state aldehydes revealed most free aldehydes in fresh beers and with higher malt modification. During aging, the equilibrium between free and bound state aldehydes shifted toward the free form. These results reveal a nitrogen-dependent bound pool of aldehydes that is depleted during aging and is responsible for aged aroma, especially in the early and medium stages of aging. Therefore, bound state aldehydes are indicators of the early-stage prediction of flavor instability already in a fresh condition.

Monitoring the evolution of free and cysteinylated aldehydes from malt to fresh and forced aged beer

During storage, beer staling coincides with a gradual increase in the concentrations of aldehydes resulting in the appearance of undesirable flavours. Cysteinylated aldehydes, also referred to as 2-substituted 1,3-thiazolidine-4-carboxylic acids, have been proposed as potential precursors of this increase. This study aimed to further understand the origin of aldehydes in aged beer, by monitoring both free and cysteinylated aldehydes throughout the brewing process, from the raw materials until the stored product. Quantification of free and cysteinylated aldehydes was performed for two different brews via headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), respectively. All selected marker aldehydes were quantified in malt, wort, and the resulting fresh and aged beer samples. Cysteinylated aldehydes were quantifiable in malt and up to the wort boiling phase. The highest levels of free aldehydes were found in malt, whereas cysteinylated aldehydes showed highest levels at mashing-in pointing to their formation during both malting and subsequent mashing-in. During beer ageing, an increase in all free aldehydes was measured. In particular, a rise in 2-methylpropanal and furfural is most striking. Although the presented experimental data obtained on malt and brewery samples do support the concept of bound-state aldehydes, cysteinylated aldehydes cannot be consider as the cause of increasing levels of staling aldehydes during beer ageing.

Insights into chemical and sensorial aspects to understand and manage beer aging using chemometrics

Beer chemical instability remains, at present, the main challenge in maintaining beer quality. Although not fully understood, after decades of research, significant progress has been made in identifying "aging compounds," their origin, and formation pathways. However, as the nature of aging relies on beer manufacturing aspects such as raw materials, process variables, and storage conditions, the chemical profile differs among beers. Current research points to the impact of nonoxidative reactions on beer quality. The effect of Maillard and Maillard intermediates on the final beer quality has become the focus of beer aging research, as prevention of oxidation can only sustain beer quality to some extent. On the other hand, few studies have focused on tracing a profile of whose compound is sensory relevant to specific types of beer. In this matter, the incorporation of "chemometrics," a class of multivariate statistic procedures, has helped brewing scientists achieve specific correlations between the sensory profile and chemical data. The use of chemometrics as exploratory data analysis, discrimination techniques, and multivariate calibration techniques has made the qualitatively and quantitatively translation of sensory perception of aging into manageable chemical and analytical parameters. However, despite their vast potential, these techniques are rarely employed in beer aging studies. This review discusses the chemical and sensorial bases of beer aging. It focuses on how chemometrics can be used to their full potential, with future perspectives and research to be incorporated in the field, enabling a deeper and more specific understanding of the beer aging picture.

Application of High-Pressure Processing to Assure the Storage Stability of Unfiltered Lager Beer

Due to the increasing popularity of unfiltered beer, new methods for its preservation are needed. High-pressure processing (HPP) was applied as a final treatment of packed beer in order to assure storage stability and to retain the desired product quality. Pressures of 250 MPa and 550 MPa for 5 min were used to process unfiltered lager beers. The impact of pressure on basic analytical characteristics was evaluated, and foam stability, the content of carbonyl compounds and sensory properties were monitored during two months of storage. Most of the basic analytical parameters remained unaffected after pressure treatment, and a beneficial effect on foam stability was demonstrated. Changes in the concentration of staling aldehydes were observed during storage. Some features of the sensory profile were affected by HPP as well as by the time of storage. Our study evaluated the suitability of HPP as a novel method for shelf-life extension of unfiltered lager beer.

Flavor stability assessment of lager beer: what we can learn by comparing established methods

Beer is prone to flavor changes during aging that influence consumer acceptance within shelf life. The shelf life of beer is defined as the period over which flavor changes remain acceptable. Assessment of flavor changes caused by volatiles is typically achieved with a combination of sensory evaluation and gas chromatography–mass spectrometry (GC–MS). Volatile indicators causing flavor changes during beer aging are commonly determined with headspace solid–phase microextraction (HS-SPME), solvent-assisted flavor evaporation (SAFE), or steam distillation (SD). However, discrepancies occur when comparing results from different analytical methods that affect the assessment of the degree of flavor stability. This article discusses the effect of different established analytical methods on flavor stability assessment. Reaction potentials of de novo formation, release from adducts, and degradation are hypothesized to participate in the observed discrepancies, and evidence is verified using model systems. Three extraction methods were qualitatively compared by multiple gas chromatography–olfactometry experiments (GC–O) of a one-year, naturally aged, pale lager beer. SD showed the highest number of detected aroma compounds (41), followed by HS-SPME (33), and SAFE (26). Aroma intensities for SD were more pronounced for most aging indicators than with other methods. With SAFE, only 11 aging compounds could be identified confidently, with weak aroma intensities at GC–O, and this method was thereby excluded from further experiments. Certain aging compounds were calibrated for gas chromatography-mass spectrometry (GC–MS) from HS-SPME and SD, although most compounds were present at the lower limits of detection and quantification. Relative standard deviation and recoveries for all compounds were acceptable for both methods. Quantitative comparison was conducted for four different commercial pale lager beers at different stages of aging at 20 °C (fresh, 5 months, 10 months). Aging-related changes of pale lager beer presented with altered profiles and behavior in SD compared to the non-invasive HS-SPME due to heat intake, and were borne out by GC–O results. Model systems were used to describe the impact of isolated aging-relevant mechanisms and precursors during distillation. Our findings suggest that results from different methods in reactive matrices should be compared cautiously, especially regarding aroma activity, and indicate that the most gentle or non-invasive method should be applied for analysis.