Profiling the volatile carbonyl compounds of barley and malt samples using a low-pressure assisted extraction system

Characterization of aroma-active compounds in sesame hulls at different roasting temperatures by SAFE and GC-O-MS

The study characterized the aroma-active compounds produced by sesame hulls at three roasting temperatures and analyzed the similarities and differences in the aroma profile of sesame hulls with whole seeds and kernels after roasting. Roasting hulls produced mainly furans, aldehydes, and ketones volatiles. 140 Compounds were identified as aroma-active compounds, including 36 key aroma compounds (odor activity value, OAV ≥ 1). Among them, furanone (caramel-like, OAV = 80), 3-methylbutanal (fruity, OAV = 124), and 2-methoxy-4-vinylphenol (burnt, smoky, OAV = 160) gave hulls (180 °C) sweet, burnt, and smoky aroma. Due to the contribution of vanillin (fatty, sweet milk, OAV = 45), 2-hydroxy-3-butanone (caramel-like, roast, OAV = 46), and 2-methoxy-4-vinylphenol (OAV = 78), hulls (200 °C) shown strong sweet and roast note. These results identified compounds that contributed significantly to the aroma of sesame hulls and elucidated the contribution of sesame hulls to the flavor of roasted whole seeds and sesame oil.

Formation response of kilned specialty malt odorant markers to controlled malting process parameters

Kilned specialty malts provide relevant colour and flavour characteristics to beer and other beverages. Alongside the thermal load, the availability of Maillard precursors directly affect the malt aroma formation. To investigate the influence of process parameters on the flavour characteristics of kilned specialty malts, a full factorial design of experiments was applied varying malt modification degree, curing temperature and time in three levels (33). Analysis of response surfaces revealed a predominant influence of the modification degree and curing temperature on the formation of Strecker aldehydes and pyrazines. Odorants such as 2-methylpropanal and 2-ethyl3,6-dimethylpyrazine presented higher concentrations varying between 429.45 and 478.22 µg∙Kgmalt-1 and 12.49 to 16.75 µg∙Kgmalt-1 respectively, at samples produced under 100 °C and high modification degree. Sensory analysis revealed strong correlations between the odorant markers and typical malt flavour attributes, endorsing the applicability of such methodology on the development and optimisation of kilned malt specialities.

UPLC-Q-TOF-MS/MS analysis on the chemical composition of malts under different germination cycles and prepared with different processing methods

OBJECTIVE

To investigate changes in the chemical composition of malts under different germination cycles and prepared with different processing methods, thus providing a reference for the clinical application of malt in disease treatment.

METHODS

Nine malt samples were analyzed by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS), and the MS fragmentation pathway of 4 compounds (including hordenine, gramine, N-methyltyramine and catechin) were also analyzed.

RESULTS

By database comparison and literature search, we detected 31 compounds in raw barley and 33 compounds in both raw malt and roasted malt. Nonetheless, the most of these 33 compounds were detected higher contents in raw malt than in roasted malt. Besides, we detected 15 compounds in brown malt. At Day1 of germination, 31 compounds were detected in malt, without two alkaloids (representative: hordenine). At Day2-5, 33 compounds were detected, with different contents as shown by the peak area comparison; hordenine had a gradually increasing abundance; and nearly one third of the chemical components in barley increased gradually, one third decreased gradually, and one third tended to be stable.

CONCLUSION

Malts under different germination cycles and prepared with different processing methods have varying active ingredients, and especially brown malt exhibits a serious loss of compounds. The tight association between the chemical composition and clinical application of malt offers a basis to the clinically scientific and reasonable selection of Chinese medicinal materials for treatment purposes.

Identification of potential odorant markers to monitor the aroma formation in kilned specialty malts

Specialty malts are strategic ingredients regarding their contribution to colour and flavour of beer. Malts with the same colour may present distinct flavour characteristics and intensities. Contradictorily, colour is the benchmark in practical quality control. To investigate the correlation between colour and flavour of kilned barley specialty malts, odorants of commercial products of pale ale (5-9 EBC), Vienna (6-10 EBC), Munich (11-35 EBC) and melanoidin malts (80-90 EBC) were screened via solvent-assisted flavour evaporation (SAFE) and compared via comparative aroma extract dilution analysis (cAEDA). Subsequently, selected odorants were quantified using solid-phase microextraction (SPME). A total of 34 odorants were detected, of which 12 exhibited a concentration increase as the coloration increased, whereas 4 suggested the influence of temperature and modification degree on aroma formation. Such odorants are thus elected as potential markers for monitoring the influence of process variations on the formation of aroma in commercial kilned specialty malts.

The complete chloroplast genome sequence of Hordeum distichon (Poales: Poaceae)

Hordeum distichon (H. distichon) is a two-row cultivated barley used as food and as a feed crop. Chloroplast genome is an excellent way to study the genetic structure and evolutionary process of natural population of plant species in recent years. In this study, the complete chloroplast genome of H. distichon was sequenced and analyzed: the size of the chloroplast genome is 136,462 bp in length, including a large single copy region (LSC) of 80,597 bp, a small single copy region (SSC) of 12,701 bp, and a pair of inverted repeated regions (IR) of 21,582 bp; the H. distichon chloroplast genome encodes 129 genes, including 83 protein-coding genes, 38 tRNA genes, and eight rRNA genes; the overall GC-content of the chloroplast genome was 38.32%, with the LSC, SSC, and IR regions being 36.31%, 32.33%, and 43.83%, respectively. Phylogenetic analysis based on 32 species with the maximum likelihood (ML) method indicated that H. distichon was closely related to Hordeum vulgare.

Aroma and color development during the production of specialty malts: A review

Specialty malts comprise a promising field for innovative approaches concerning their potential in terms of color, aroma, and taste influence on the composition of beer and other beverages. Nevertheless, poor reproducibility of aroma and taste is a recurrent struggle between maltsters, leaving color as a practical parameter for quality control. However, malts with similar coloration can present distinct aroma profiles, leaving open questions concerning key aroma compounds, their dynamic responses to malting process variations and to what extent they may vary in a certain color range. Key aroma volatiles have been identified in the matrix of barley malt, comprising a variety of products of non-enzymatic browning reactions (e.g., caramelization, pyrolysis, and Maillard reactions). Here, water plays a crucial role together with the intensity of the temperature regimes. Nevertheless, the final aroma profile of a malt product is the result of a balance between aroma formation and losses. Therefore, the correlation between color and aroma is of big complexity. That being the case, the present article questions if key aroma compounds responsible for the peculiar flavors of specialties have been defined by scientific literature and whether their production dynamics is unveiled. In this manner, this work proposes an overview of the aroma compounds present in specialty malt products studied up to the current date. More specifically, the process production of specialty malts and its potential impact on the formation of aroma and taste is studied alongside the key aroma-active compounds, their correlation to color, and trending analytical techniques for aroma and color assessment.