A new physical and biological strategy to reduce the content of zearalenone in infected wheat kernels: the effect of cold needle perforation, microorganisms, and purified enzyme.

With the aim of reintroducing wheat grains naturally contaminated with mycotoxins into the food value chain, a decontamination strategy was developed in this study. For this purpose, in a first step, the whole wheat kernels were pre-treated using cold needle perforation. The pore size was evaluated by scanning electron microscopy and the accessibility of enzymes and microorganisms determined using fluorescent markers in the size range of enzymes (5 nm) and microorganisms (10 µm), and fluorescent microscopy. The perforated wheat grains, as well as non-perforated grains as controls, were then incubated with selected microorganisms (Bacillus megaterium Myk145 and B. licheniformis MA572) or with the enzyme ZHD518. The two bacilli strains were not able to significantly reduce the amount of zearalenone (ZEA), neither in the perforated nor in the non-perforated wheat kernels in comparison with the controls. In contrast, the enzyme ZHD518 significantly reduced the initial concentration of ZEA in the perforated and non-perforated wheat kernels in comparison with controls. Moreover, in vitro incubation of ZHD518 with ZEA showed the presence of two non-estrogenic degradation products of ZEA: hydrolysed zearalenone (HZEA) and decarboxylated hydrolysed ZEA (DHZEA). In addition, the physical pre-treatment led to a reduction in detectable mycotoxin contents in a subset of samples. Overall, this study emphasizes the promising potential of combining physical pre-treatment approaches with biological decontamination solutions in order to address the associated problem of mycotoxin contamination and food waste reduction.

Influence of Aerobic and Anaerobic Moist Incubation on Selected Nonvolatile Constituents─Comparison to Traditionally Fermented Cocoa Beans.

Recently, moist incubation has been proposed as an alternative postharvest processing method for cocoa beans. During this treatment, unfermented and dried cocoa nibs are rehydrated with a lactic acid solution containing ethanol and subsequently incubated for 72 h at 45 °C before drying. Previous studies focused on the aroma formation during this treatment and the further processing of chocolate. The current study focused on the influence of aerobic and anaerobic moist incubation on selected nonvolatile components in comparison with the unfermented raw material and traditionally fermented cocoa. Total phenolic content and total flavan-3-ol content, contents of (+)-catechin, (-)-epicatechin, procyanidins B2 and C1, cinnamtannin A2, methylxanthines (theobromine and caffeine), contents of sugars (sucrose, d-glucose, and d-fructose) and free amino acids (17 proteinogenic amino acids) were determined. The fermentation index was also evaluated. The aerobically incubated and fermented cocoa showed low levels of phenolic compounds in comparison to the unfermented cocoa and the anaerobically incubated cocoa. The level of methylxanthines was unaffected by all treatments. The contents of reducing sugars were more than 2-fold higher after both incubation treatments compared to fermentation. The level of free amino acids liberated was highest after anaerobic incubation followed by fermentation and aerobic incubation. The aerobically incubated cocoa showed the highest FI, while the anaerobically incubated cocoa may be considered under-fermented (FI <1.0). Statistical analysis (ANOVA) showed significant differences between all treatments, which was verified by principal component analysis.

Use of molecular networking to identify 2,5-diketopiperazines in chocolates as potential markers of bean variety.

2,5-diketopiperazines are cyclic dipeptides found, among others, in chocolate. Although those compounds are contributing greatly to its pleasant bitterness, they can also be seen as interesting markers of cocoa beans processing. To evaluate the influence of bean variety and processing technology on the quantity of 2,5-diketopiperazines formed in chocolates, HPLC-MS/MS analyses were conducted, and a molecular network was built with the MS2 data. This approach eases the identification of 2,5-diketopiperazines within complex datasets and allows to visualize the chemical diversity of all samples. Using this methodology, 33 dark chocolates were analysed. 18 different diketopiperazine were identified and quantified. Among them, cyclo(L-ile-L-val), cyclo(L-leu-L-ile) and cyclo(L-phe-L-phe) were, to the best of our knowledge, detected for the first time in chocolate. The molecular network allows the clear visualization of differences between samples. The principal component analysis revealed the clustering of small batch chocolate samples according to bean variety, suggesting that bean genotype has a strong influence on the 2,5-diketopiperazines content of bean-to-bar chocolates, regardless of the degree of roasting or the technological process used by the small producers. The presence of two unique diastereoisomers in the classical chocolates bought in the supermarket indicates that the beans have probably undergone a more intense heat treatment. This study proposes the use of 2,5-diketopiperazines as potential markers of cocoa beans variety, as well as an indicator of post-harvest processing and processing technology, and highlights the potential of the molecular networks in the field of food and drink innovation as a promising tool to understand the complex chemistry of flavours.

Decoding the Fine Flavor Properties of Dark Chocolates.

Fine flavor properties of chocolates such as fruity, floral, and cocoa-like were decoded on a molecular level for the first time. The molecular compositions of six chocolates made out of liquors that were referenced with specific sensory attributes were analyzed. After the screening for odor-active molecules by aroma extract dilution analysis, selected compounds were quantitated with the overall aim to decode the distinct fine flavor attributes on a molecular level. Acidic and fruity flavor notes were associated with high dose over threshold factors (DoT factors) of acetic acid and fruity smelling esters such as ethyl 2-methylbutanaote, ethyl 3-methylbutanoate, and 3-methylbutyl acetate, respectively. Cocoa-like and roasty flavor notes were associated with high DoT factors for 2-methylbutanal, 3-methylbutanal, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, and dimethyltrisulfane. The floral and astringent flavors were linked to high DoT factors of (-)-epicatechin, procyanidin B2, procyanidin C1, and 2-phenylethan-1-ol.

Comparison of the Aroma Composition and Sensory Properties of Dark Chocolates Made with Moist Incubated and Fermented Cocoa Beans.

In a previous investigation, "moist incubation" was described as a novel postharvest treatment for cocoa and the aroma composition of the resulting cocoa nibs was compared to unfermented and fermented cocoa nibs. For this treatment, unfermented and dried nibs are rehydrated with an aqueous solution containing lactic acid and ethanol to adjust the pH value and are subsequently incubated at 45 °C under aerobic conditions for 72 h before drying. The aim of the present study was to investigate the sensory properties and aroma composition of dark chocolates made of these materials after roasting. Therefore, gas chromatography-olfactometry (GC-O) in combination with aroma extract dilution analysis (AEDA), quantitation with isotopically labeled standards, odor activity value (OAV) determination, and sensory analysis were performed. The three different chocolates had distinct sensory and OAV profiles. The sensory profiles showed a higher intensity of fruity aroma notes and a lower intensity of bitterness and astringency in the chocolate made with the moist incubated cocoa, while the chocolate made of fermented cocoa reached higher scores in the roasty aroma notes. Furthermore, higher OAVs were determined for the Strecker aldehydes in the chocolate made of the moist incubated cocoa, whereas higher OAVs for the pyrazines and the acids were detected in the chocolate made of fermented cocoa. In contrast, the chocolate produced with the unfermented cocoa showed low cocoa specific aroma notes and high levels of astringency and bitterness. The detected differences reveal interesting insights into the influence of different postharvest treatments on the resulting aroma composition in the final chocolate. Furthermore, the alternative postharvest treatment was demonstrated to result in chocolates with a pleasant sensory profile.

Impact of Water on Odor-Active Compounds in Fermented and Dried Cocoa Beans and Chocolates Made thereof.

The impact of water on odor-active compounds in fermented and dried cocoa beans as well as in chocolate either produced by a novel processing (NPC) or a traditional processing (TPC) technology from the same batch of cocoa beans was investigated in this study. Quantitation of selected key odorants revealed significantly higher concentrations of Strecker aldehydes such as 3-(methylsulfanyl)propanal (66-fold) and phenylacetaldehyde (50-fold) after water treatment of the cocoa beans. The comparison of the two chocolates showed that higher amounts of the Strecker aldehydes 2-methylbutanal, 3-methylbutanal, and phenylacetaldehyde are released with water in the NPC (24-fold to 39-fold), compared to the TPC (7.3-fold-11-fold). In addition to Strecker aldehydes, the concentrations of many further characteristic key odorants of cocoa and chocolate increased after water treatment. Based on the results, a more intense retronasal odor perception of the analyzed compounds is expected due to their release during consumption in contact with saliva.

Evolution of the Polyphenol and Terpene Content, Antioxidant Activity and Plant Morphology of Eight Different Fiber-Type Cultivars of Cannabis Sativa L. Cultivated at Three Sowing Densities.

The chemical composition of the inflorescences of eight different fibre-type Cannabis sativa L. cultivars grown in Switzerland was monitored for different sowing densities over the season 2019. HPLC-MS, GC-MS and GC-FID, as well as spectrophotometric techniques were used to measure the total phenolic content (TPC) and the antioxidative activity of the inflorescence extracts, and to characterise and quantify the flavonoids and terpenes produced by the different cultivars over different sowing densities from July to September 2019. The main finding of the present study is that the TPC, as well as the individual flavonoids and terpenes, were mainly influenced by the harvest period and the phenological stage of the plant. The content of polyphenols and flavonoids decrease during the flower development for all cultivars studied. The terpene content increased with maturation. The monoterpenes/sesquiterpenes ratio also changed between the early flowering (majority of sesquiterpenes) and the end of flowering (majority of monoterpenes). The sowing density showed an impact on plant morphology, a low density such as 30 seeds/m2 influencing the production of bigger flowers, thus increasing the yield of polyphenols and terpenes production. Therefore, hemp inflorescences can be regarded as valuable by-products of fibre production, for their valorisation in the food and beverage industry in addition to cosmetics and perfumery.

Novel Time- and Location-Independent Postharvest Treatment of Cocoa Beans: Investigations on the Aroma Formation during "Moist Incubation" of Unfermented and Dried Cocoa Nibs and Comparison to Traditional Fermentation.

The aroma properties of cocoa nibs obtained by applying a novel postharvest treatment were investigated using methods of the molecular sensory science approach, i.e., solvent extraction and solvent-assisted flavor evaporation, aroma extract dilution analysis (AEDA), stable isotope dilution analysis, calculation of odor activity values (OAVs), and orthonasal sensory evaluation; those properties were then compared to the unfermented and dried raw material and a traditionally fermented sample of the same harvest. For the treatment, unfermented and dried cocoa nibs were, first, rehydrated with lactic acid and ethanol solution to adjust the pH value to 5.1 and, second, incubated under aerobic conditions for 72 h at 45 °C and subsequently dried. This treatment was used to induce enzymatic reactions within the cotyledon matrix, which also occur inside the bean during microbial fermentation of the surrounding fruit pulp. The results of the AEDA showed that many of the key aroma compounds found in fermented and dried cocoa increased during the incubation treatment. Especially some "fruity" esters were found with an equal or even higher flavor dilution (FD) factor in the incubated sample compared to the fermented sample, whereas the fermented sample showed high FD factors for "pungent, sour" and "sweaty" acids, such as acetic acid and 2- and 3-methylbutanoic acids. The quantitative data and calculated OAVs for the samples supported the findings of the AEDA, underlining the potential of this approach as a controllable and reproducible alternative postharvest treatment.

Characterization of the Flavor Properties of Dark Chocolates Produced by a Novel Technological Approach and Comparison with Traditionally Produced Dark Chocolates.

Dark chocolates produced by a novel technological approach (NCs) were characterized in comparison with those traditionally produced (TCs) by sensory evaluation, gas chromatography-olfactometry in combination with aroma extract dilution analysis, quantitation of the aroma-relevant chocolate odorants by stable isotope dilution assays, and calculation of the odor activity values (OAVs). The results of the sensory investigation by cluster analysis clearly showed a differentiation between the NC and the TC samples. The findings of the aroma measurements revealed that NCs were characterized by low OAVs of volatile acids such as acetic and 3-methylbutanoic acid and high OAVs especially for the esters ethyl 2-methylbutanoate and ethyl 3-methylbutanoate in comparison to TC samples. In contrast to that, no relevant differences could be observed for thermally generated compounds such as Strecker aldehydes and pyrazines.

Bioactive Compound Fingerprint Analysis of Aged Raw Pu'er Tea and Young Ripened Pu'er Tea.

Pu'er tea produced from Camellia sinensis var. assamica is a widely appreciated and consumed beverage that can be divided into two kinds of tea depending on the different fermentation processed used, the special sensory characteristics, and their chemical composition. However, authentication seems to be very important for such teas, as they are traded to comparatively high prices, especially in Europe. The results for selected biochemical markers showed that aged raw pu'er tea contained 210.2 mg GAE/g polyphenols, of which 2.2 mg/g were gallic acid, 16.1 mg/g theogallin, 35.1 mg/g (-)-epigallocatechin gallate, and 40.1 mg/g (-)-epicatechin gallate, on average. Young ripened pu'er tea contained about 104.6 mg GAE/g polyphenols, of which 5.5 mg/g gallic acid, 0.9 mg/g theogallin, 0.7 mg/g (-)-epigallocatechin gallate, and 1.8 mg/g (-)-epicatechin gallate, on average. An additional objective of the present study was to unravel the best brewing conditions for optimal extraction of the bioactive compounds. Infusions of nineteen commercial teas (from pu'er cakes) were obtained at different time-temperature ratios for studying the content of bioactive compounds (flavan-3-ols, flavonols, caffeoylquinic acids, methylxanthines). Brewing at 90 °C for 5 min was the best condition to obtain a high content of total polyphenols in ripened pu'er tea. Principal component analysis and hierarchical cluster analysis showed, that young ripened and aged raw pu'er tea can be successfully differentiated by the analyzed chemical compounds. Principal component analysis results indicated that young ripened pu'er tea has higher contents of gallic acid, quercetin, and kaempferol than aged raw pu'er tea.

Investigations on the Aroma of Cocoa Pulp ( Theobroma cacao L.) and Its Influence on the Odor of Fermented Cocoa Beans.

The odor-active constituents of cocoa pulp have been analyzed by aroma extract dilution analysis (AEDA) for the first time. Pulps of three different cocoa varieties have been investigated. The variety CCN51 showed low flavor intensities, in terms of flavor dilution (FD) factors, in comparison to varieties FSV41 and UF564, for which floral and fruity notes were detected in higher intensities. To gain first insights on a molecular level of how the cocoa pulp odorants affected the odor quality of cocoa beans during fermentation, quantitative measurements of selected aroma compounds were conducted in pulp and bean at different time points of the fermentation. The results showed significantly higher concentrations of 2-phenylethanol and 3-methylbutyl acetate in pulp than in the bean during the different time steps of the fermentation, whereas the reverse could be observed for the odorants linalool and 2-methoxyphenol. The findings of this study constitute a basis for further investigations on the aroma formation of cocoa during fermentation.

Quantitation of key peanut aroma compounds in raw peanuts and pan-roasted peanut meal. Aroma reconstitution and comparison with commercial peanut products.

By means of stable isotope dilution assays (SIDA), 26 odor-active compounds, previously characterized by GC-olfactometry (GC-O), were quantitated in raw peanuts, and the concentrations of 38 odorants were determined in pan-roasted peanut meal. On the basis of the quantitative data and odor thresholds determined in vegetable oil, the odor activity values (OAVs) of the most important aroma compounds in raw as well as in pan-roasted peanut meal were calculated. 3-Isopropyl-2-methoxypyrazine, acetic acid, and 3-(methylthio)propanal showed the highest OAVs in raw peanuts, whereas methanethiol, 2,3-pentanedione, 3-(methylthio)propanal, and 2- and 3-methylbutanal as well as the intensely popcorn-like smelling 2-acetyl-1-pyrroline revealed the highest OAV in the pan-roasted peanut meal. Aroma recombination studies confirmed the importance, in particular, of methanethiol and of lipid degradation products in the characteristic aroma of the freshly roasted peanut material. To evaluate additive effects on the overall aroma, the concentrations of eight pyrazines, previously not detected by GC-O among the odor-active volatiles, were additionally quantitated in the pan-roasted peanut meal. A sensory experiment in which the eight pyrazines were added to the recombinate clearly revealed that these volatiles did not show an impact on the overall aroma. Finally, selected odorants were quantitated in commercial peanut products to confirm their important role in peanut aroma.

Comparison of the key aroma compounds in organically grown, raw West-African peanuts (Arachis hypogaea) and in ground, pan-roasted meal produced thereof.

Application of an aroma extract dilution analysis on an aroma distillate prepared from organically grown, raw West-African peanuts (Cameroon) revealed 36 odor-active areas in the flavor dilution (FD) factor range of 1 to 2048. The identification experiments, which were all performed by using the respective reference chemicals, revealed 2-isopropyl-3-methoxypyrazine (earthy, pea-like), 2-isobutyl-3-methoxypyrazine (bell pepper-like, earthy), and trans-4,5-epoxy-(E)-2-decenal (metallic) with the highest FD factors among the 36 aroma compounds identified. The two last mentioned odorants and another set of 22 further odorants were identified for the first time in raw peanuts. A comparative aroma extract dilution analysis applied on distillates prepared from either the raw peanuts or ground peanut meal roasted in a pan showed 52 odor-active areas in the FD factor range of 8 to 2048 in the roasted nut material. The identification experiments in combination with the FD factors revealed that among them, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone showed the most significant contribution to the overall aroma, followed by 1-octen-3-one, 2-isopropyl-3-methoxypyrazine, (E, E)-2,4-decadienal, and trans-4,5-epoxy-(E)-2-decenal. As a further result, 20 aroma compounds were newly identified in roasted peanuts, such as 2-propionyl-1-pyrroline and 2-acetyltetrahydropyridine (both popcorn-like). In particular, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3(2 H)-furanone showed the most pronounced increase after roasting.