Multivariate analysis of chemical and genetic diversity of wild Humulus lupulus L. (hop) collected in situ in northern France.

The hop plant (Humulus lupulus L.) has been exploited for a long time for both its brewing and medicinal uses, due in particular to its specific chemical composition. These last years, hop cultivation that was in decline has been experiencing a renewal for several reasons, such as a craze for strongly hopped aromatic beers. In this context, the present work aims at investigating the genetic and chemical diversity of fifty wild hops collected from different locations in Northern France. These wild hops were compared to ten commercial varieties and three heirloom varieties cultivated in the same sampled geographical area. Genetic analysis relying on genome fingerprinting using 11 microsatellite markers showed a high level of diversity. A total of 56 alleles were determined with an average of 10.9 alleles per locus and assessed a significant population structure (mean pairwise FST = 0.29). Phytochemical characterization of hops was based on volatile compound analysis by HS-SPME GC-MS, quantification of the main prenylated phenolic compounds by UHPLC-UV as well as untargeted metabolomics by UHPLC-HRMS and revealed a high level of chemical diversity among the assessed wild accessions. In particular, analysis of volatile compounds revealed the presence of some minor but original compounds, such as aromadendrene, allo-aromadendrene, isoledene, ß-guaiene, α-ylangene and ß-pinene in some wild accessions; while analysis of phenolic compounds showed high content of ß-acids in these wild accessions, up to 2.37% of colupulone. Genetic diversity of wild hops previously observed was hence supported by their chemical diversity. Sample soil analysis was also performed to get a pedological classification of these different collection sites. Results of the multivariate statistical analysis suggest that wild hops constitute a huge pool of chemical and genetic diversity of this species.

Sensopeptidomic Kinetic Approach Combined with Decision Trees and Random Forests to Study the Bitterness during Enzymatic Hydrolysis Kinetics of Micellar Caseins.

Protein hydrolysates are, in general, mixtures of amino acids and small peptides able to supply the body with the constituent elements of proteins in a directly assimilable form. They are therefore characterised as products with high nutritional value. However, hydrolysed proteins display an unpleasant bitter taste and possible off-flavours which limit the field of their nutrition applications. The successful identification and characterisation of bitter protein hydrolysates and, more precisely, the peptides responsible for this unpleasant taste are essential for nutritional research. Due to the large number of peptides generated during hydrolysis, there is an urgent need to develop methods in order to rapidly characterise the bitterness of protein hydrolysates. In this article, two enzymatic hydrolysis kinetics of micellar milk caseins were performed for 9 h. For both kinetics, the optimal time to obtain a hydrolysate with appreciable organoleptic qualities is 5 h. Then, the influence of the presence or absence of peptides and their intensity over time compared to the different sensory characteristics of hydrolysates was studied using heat maps, random forests and regression trees. A total of 22 peptides formed during the enzymatic proteolysis of micellar caseins and influencing the bitterness the most were identified. These methods represent simple and efficient tools to identify the peptides susceptibly responsible for bitterness intensity and predict the main sensory feature of micellar casein enzymatic hydrolysates.

Principal Component Analysis from Mass Spectrometry Data Combined to a Sensory Evaluation as a Suitable Method for Assessing Bitterness of Enzymatic Hydrolysates Produced from Micellar Casein Proteins.

Enzymatic hydrolysis of food proteins generally changes the techno-functional, nutritional, and organoleptic properties of hydrolyzed proteins. As a result, protein hydrolysates have an important interest in the food industries. However, they tend to be characterized by a bitter taste and some off-flavors, which limit their use in the food industry. These tastes and aromas come from peptides, amino acids, and volatile compounds generated during hydrolysis. In this article, sixteen more or less bitter enzymatic hydrolysates produced from a milk protein liquid fraction enriched in micellar caseins using commercially available, food-grade proteases were subjected to a sensory analysis using a trained and validated sensory panel combined to a peptidomics approach based on the peptide characterization by reverse-phase high-performance liquid chromatography, high-resolution mass spectrometry, and bioinformatics software. The comparison between the sensory characteristics and the principal components of the principal component analysis (PCA) of mass spectrometry data reveals that peptidomics constitutes a convenient, valuable, fast, and economic intermediate method to evaluating the bitterness of enzymatic hydrolysates, as a trained sensory panel can do it.

Influence of meat source, pH and production time on zinc protoporphyrin IX formation as natural colouring agent in nitrite-free dry fermented sausages.

Nitrite is commonly used in meat products due to its plural technological advantages. However, it is controversial because of its detrimental side effects on health. Within the context of nitrite reduction, zinc protoporphyrin IX (Zn(II)PPIX) formation in meat products as natural red colouring agent has been suggested. This investigation presents the evaluation of naturally occurring pigments, namely Zn(II)PPIX, protoporphyrin IX (PPIX) and heme in nitrite-free dry fermented sausages in function of time, meat source (pork, horsemeat and a combination of both meat sources) and pH condition. In function of time, Zn(II)PPIX and PPIX were formed and heme content decreased. Higher pH conditions promoted Zn(II)PPIX and PPIX formation, whereas the influence of pH on heme was less clear. The use of horsemeat also promoted Zn(II)PPIX formation. Moreover, even similar amounts were formed when it was combined with pork. Product redness, however, could not be related to Zn(II)PPIX formation.

The building blocks of drinking experience across men and women: A case study with craft and industrial beers.

In today's market, every product seems to be marked by the label of "experience". It is expected that successful products give the consumer "extraordinary experiences". The research in consumption experience is growing, but much work still needs to be done to understand the food and beverage experience. A qualitative study was conducted using contextual focus groups to explore the building blocks of consumers' drinking experience of industrial and craft beers. The results show that drinking experience is shaped by our cognitive, sensory or affective systems, especially during the core consumption experience. Elements such as attitudes, consumption habits, and individual versus social consumption, shopping experience and product benefits are also responsible for shaping the experience, but are more relevant during the pre-consumption or post-consumption experience. Gender differences occur more frequently in the affective experience, as women search more for relaxation while men for excitement and stimulation while drinking beer. When comparing industrial users versus craft, in the latter the cognitive and shopping experiences are more relevant. Overall, the results showed that the drinking experience of beers can be studied as a function of the salient human system used during product interaction, and this systems act as the building blocks of the drinking experience of beer. This information can be applied in consumer research studies to further study the experiential differences across products and consumers.

MALDI-TOF mass spectrometry for the identification of lactic acid bacteria isolated from a French cheese: The Maroilles.

In this study we identified the culturable population of mesophilic lactic acid bacteria (LAB) from a French cheese Maroilles made either with raw or pasteurized milk using MALDI-TOF mass spectrometry (MS). Samples from rind and heart of Maroilles cheese were used, the LAB were selected on MRS agar at 30°C and 197 Gram-positive and catalase-negative strains were subjected to identification by MALDI-TOF MS profiling. All strains were unambiguously identified: 105 strains from Maroilles made with raw milk (38 on the rind and 67 in the heart) and 92 strains from Maroilles made with pasteurized milk (39 on the rind and 53 in the heart). MALDI-TOF MS identification allowed identification of three genera belonging to LAB including Lactobacillus, Enterococcus and Leuconostoc. Lactobacillus was the most represented genus with seven species: Lactobacillus plantarum (L. plantarum), L. paracasei, L. curvatus, L. rhamnosus, L. fructivorans, L. parabuchneri, L. brevis found in Maroilles made with both kind of milk. The correlation between the 16S rDNA-based identification performed on selected strains and those obtained by MALDI-TOF-MS demonstrates that this fast, economically affordable, robust and reliable method for bacteria characterisation stands as an attractive alternative to the commonly-used methods and its application in food industry is discussed.

Effect of Germination and Fermentation Process on the Antioxidant Compounds of Quinoa Seeds.

Quinoa (Chenopodium quinoa) seed has gained a great interest in the last years, mainly due to its nutritional properties and its content of antioxidant substances with health-promoting properties in humans. In this work, the effect of germination time and fermentation on the levels of antioxidant compounds (ascorbic acid, tocopherol isomers and phenolic compounds) and antioxidant activity of quinoa seeds was evaluated. Fermentation was carried out naturally by the microorganisms present in the seeds or by inoculation with two Saccharomyces cerevisiae strains (used for baking and brewing). Ascorbic acid and total tocopherols were significantly increased (p ≤ 0.05) after 72 h of germination process in comparison with raw quinoa seeds, whilst fermentation caused a decrease in both types of compounds. Phenolic compounds and antioxidant capacity were improved using both bioprocesses, being this effect more noticeable for germination process (101 % of increase after three days of germination). Germination and fermentation proved to be desirable procedures for producing enriched ingredients with health-promoting antioxidant compounds in a natural way.

Formation of naturally occurring pigments during the production of nitrite-free dry fermented sausages.

This study investigates the potential of producing red coloured dry fermented sausages without the addition of nitrite and/or nitrate. Therefore, the formation of zinc protoporphyrin IX (Zn(II)PPIX) as naturally occurring pigment, and the interrelated protoporphyrin IX (PPIX) and heme content were evaluated during nitrite-free dry fermented sausage production at different pH conditions. Zn(II)PPIX was only able to form in dry fermented sausages at pH conditions higher than approximately 4.9. Additionally, the presence of Zn(II)PPIX increased drastically at the later phase of the production process (up to day 177), confirming that in addition to pH, time is also a crucial factor for its formation. Similarly, PPIX also accumulated in the meat products at increased pH conditions and production times. In contrast, a breakdown of heme was observed. This breakdown was more gradual and independent of pH and showed no clear relationship with the formed amounts of Zn(II)PPIX and PPIX. A statistically significant relationship between Zn(II)PPIX formation and product redness was established.

Craft vs. industrial: Habits, attitudes and motivations towards beer consumption in Mexico.

Food choices tend to be stable over time; they do not change fast, since consumers tend to act like creatures of habits. However, food habits can evolve, like currently the craft beer category. A change of habits involves a change of perception towards a product. Therefore, what is changing in the perception of beer? Two studies were conducted to address this question. First study was preliminary and aimed at exploring beer consumption habits in Mexico and a better understanding of craft beer representation among beer users. A questionnaire was administrated to 207 consumers in Mexico City during a beer festival. Results showed that respondents could be classified in: industrial beer (41.1%), occasional industrial (24.1%), and craft beer (34.8%) consumers. Craft cluster included mostly 25-35 years old men with high-income level. Among the craft beers cited by respondents from this cluster some are industrial, suggesting that the concept of craft beer might not be well defined, or defined in ideological terms. The second and main study was conducted using consumer ethnographies to understand the motivations and benefits of craft beer consumption. Opposite to industrial, craft beer emerges as an experience-based and symbolic product rather than a utilitarian one. The main motivation for drinking craft beer seems to be the quest of authenticity. Respondents' motivations to drink craft beer are generated by three important factors: desire for more knowledge, new taste experiences, and move away from the mainstream beer consumption. Craft consumers do not drink the product for its functional attributes, they consume it for what it means and as a consequence they build an identity, perceived as more authentic and unique, in comparison to the mainstream industrial beer consumption in Mexico.

Becoming a beer expert: is simple exposure with feedback sufficient to learn beer categories?

Category learning is an important aspect of expertise development which had been little studied in the chemosensory field. The wine literature suggests that through repeated exposure to wines, sensory information is stored by experts as prototypes. The goal of this study was to further explore this issue using beers. We tested the ability of beer consumers to correctly categorize beers from two different categories (top- and bottom-fermented beers) before and after repeated exposure with feedback to beers from these categories. We found that participants learned to identify the category membership of beers to which they have been exposed but were unable to generalize their learning to other beers. A retrospective verbal protocol questionnaire administrated at the end of the experiment indicates that contrary to what was suggested in the wine literature, prototype extraction is probably not the only mechanism implicated in category learning of foods and beverages. Exemplar-similarity and feature-frequency models might provide a better account of the course of learning of the categorization task studied.