Effect of Heat Treatment on Antioxidant Capacity and Flavor Volatiles of Mead

Key Odorants Forming Aroma of Polish Mead: Influence of the Raw Material and Manufacturing Processes

Mead was analyzed by using the concept of molecular sensory science for the identification of key odorants. A total of 29 odor-active compounds were identified in mead by using gas chromatography olfactometry (GCO). Flavor dilution (FD) factors of identified compounds ranged from 1 to 16,384, compounds with FD factors ≥32 were quantitated by using stable isotopically substituted odorants as internal standards or external standard method, and odor activity values (OAVs) were calculated. Fifteen compounds showed OAVs ≥1: aldehydes (2-phenylacetaldehyde, 3-(methylsulfanyl)propanal), 4-hydroxy-3-methoxybenzaldehyde), esters (ethyl 3-methylbutanoate, ethyl propanoate, ethyl octanoate), alcohols (2-phenylethan-1-ol, 3- and 2-methylbutan-1-ol, 3-(methylsulyfanyl)propan-1-ol), furanons (4-hydroxy-2,5-dimethylfuran-3(2H)-one, 3-hydroxy-4,5-dimethylfuran-2(5H)-one), acids (3- and 2-methylbutanoic acid, acetic acid), 1,1-diethoxyethane, and 4-methylphenol. 2-Phenylacetaldehyde (OAV, 3100) was suggested as the compound with the biggest influence on the aroma of mead, followed by 4-hydroxy-2,5-dimethylfuran-3(2H)-one (OAV, 1900), 3-(methylsulfanyl)propanal (OAV, 890), and 2-phenylethan-1-ol (OAV, 680). Quantitative olfactory profile analysis revealed strong honey, malty, and alcoholic impressions. Omission experiments revealed that 3-(methylsulfanyl)propanal, 2-phenylethan-1-ol, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, ethyl propanoate, ethyl 3-methylbutanoate, 2-phenylacetaldehyde, 3- and 2-methylbutanoic acid, 3-hydroxy-4,5-dimethylfuran-2(5H)-one, and 4-hydroxy-3-methoxybenzaldehyde were the key odorants in the mead. Determining concentrations of key odorants in important production steps showed that the fermentation and maturation stages had the strongest effect on the formation of mead aroma.

Comparison of Volatile Profiles of Meads and Related Unifloral Honeys: Traceability Markers

Volatile profiles of unifloral honeys and meads prepared in different ways (boiled-saturated, not boiled-unsaturated) were investigated by headspace solid-phase micro extraction (HS-SPME) and dehydration homogeneous liquid–liquid extraction (DHLLE) followed by GC-FID/MS analyses. The obtained data were analyzed by principal component analysis (PCA) to evaluate the differences between the investigated products. The volatile profiles of honey as well as the boiled and the not boiled meads prepared from it showed significant discrepancies. The meads contained more aliphatic acids and esters but fewer monoterpenes and aliphatic hydrocarbons than the honey. Significant/substantial differences were found between the boiled (more aliphatic alcohols and acids) and the not boiled meads (more aliphatic hydrocarbons and esters). Some compounds related to yeast metabolism, such as tryptophol, may be considered markers of honey fermentation. This research allowed us to identify chemical markers of botanical origin, retained and detectable in the meads: 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid and 4-(1-hydroxy-2-propanyl)cyclohexa-1,3-diene-1-carboxylic acid for linden; valeric acid, γ-valerolactone, p-hydroxybenzoic acid for buckwheat; 4-hydroxybenzeneacetic acid, homovanillic acid and trans-coniferyl alcohol for honeydew; and methyl syringate for canola.

Effect of Wort Boiling on Volatiles Formation and Sensory Properties of Mead

Mead is an alcoholic beverage based on bee honey, which can be prepared in different variations such as modified honey-water compositions, the addition of spices, and the use of different yeast strains. Moreover, the technological process of mead production such as the step of wort preparation (with or without boiling of wort before fermentation) can be modified. All these factors might have a significant impact on the formation of aroma-active compounds, and therefore, sensory acceptance by consumers. High vacuum distillation, using the so-called solvent assisted flavor evaporation (SAFE) technique, or headspace-solid phase microextraction (HS-SPME) were applied for the isolation of the odorants. A sensory profile was used to monitor the changes in the aroma of the mead samples. Twenty-eight aroma-active compounds were detected during aroma extract dilution analysis (AEDA) based on gas chromatography-olfactometry (GC-O) and were finally identified by gas chromatography-mass spectrometry (GC-MS) using authentic reference compounds, including methyl propanoate, methyl 3-(methylthio)propanoate, and methional, all of them were identified for the first time in mead. Compounds with high flavor dilution (FD) factors were quantitated via stable isotope dilution analysis (SIDA) and revealed ethyl acetate (16.4 mg/L) to be the most abundant volatile compound, increasing to 57 mg/L after wort boiling, followed by ethyl hexanoate (both 1.2 mg/L). Furthermore, key aroma compounds were esters such as ethyl hexanoate, ethyl octanoate, and ethyl 3-methylbutanoate. The sensory panel evaluated ethanolic, honey-like, clove-like, sweet, and fruity notes as the main aroma descriptors of mead. The significant change in sensory evaluation was noted in the sweet odor of the heat-treated mead.

Mead Production Using Immobilized Cells of Saccharomyces cerevisiae: Reuse of Sodium Alginate Beads

This work studied the production of mead using second category honey and the immobilized cells of Saccharomyces cerevisiae in sodium alginate, with concentrations of 2% and 4%, and their reuse in five successive fermentations. The immobilized cells with 4% alginate beads were mechanically more stable and able to allow a greater number of reuses, making the process more economical. The fermentation’s consumption of sugars with free cells (control) and immobilized cells showed a similar profile, being completed close to 72 h, while the first use of immobilized cells finished at 96 h. The immobilized cells did not significantly influence some oenological parameters, such as the yield of the consumed sugars/ethanol, the alcohol content, the pH and the total acidity. There was a slight increase in the volatile acidity and a decrease in the production of SO2. The alginate concentrations did not significantly influence either the parameters used to monitor the fermentation process or the characteristics of the mead. Mead fermentations with immobilized cells showed the release of cells into the wort due to the disintegration of the beads, indicating that the matrix used for the yeast’s immobilization should be optimized, considering the mead production medium.

Characterization of a new type of mead fermented with Cannabis sativa L. (hemp)

Mead, one of the oldest existing drinks, is a fermented product based on honey, water, and the possible addition of spices and selected yeasts. In this work, various parts (inflorescences, leaves, and steams) of Cannabis sativa L. at different concentrations and Saccharomyces cerevisiae biotype M3/5 were added during mead fermentation. The physicochemical parameters (pH, alcoholic content, sugar content, titratable acidity, and organic acids) of the mead were assessed at the beginning and end of fermentation. Moreover, polyphenols, cannabidiol and volatile organic compounds were identified at the end of fermentation and compared with the control sample prepared without hemp and with only indigenous yeasts. The mead fermented with hemp showed the highest quantity of polyphenols (227 to 256 mg GAE/L) and a level of cannabidiol ranging from 0.26 to 0.49 mg/kg. The volatile organic compounds found were mainly alcohols, esters and terpenes, which were present at higher concentrations in the mead prepared with C. sativa L. than in the control mead and conferred freshness and "hemp aroma" characteristics. PRACTICAL APPLICATION: Inflorescences, leaves, and steams of Cannabis sativa L. were added at different concentrations during mead fermentation. This type of mead showed high quantity of polyphenols (227 to 256 mg GAE/L) and a level of cannabidiol ranging from 0.26 to 0.49 mg/kg which have anxiolytic and neuro-protective properties. Moreover the volatile organic compounds found (mainly alcohols, esters, and terpenes) conferred freshness and "hemp aroma" characteristics.

Characterizing the chemical and sensory profiles of traditional American meads

The compositional and sensorial profiles of traditional American meads were determined using standard enological, volatile, and descriptive analyses. Forty-one commercial meads produced by 35 meaderies across 20 states were selected to encompass a broad product range. The meads were analyzed for ethanol content, residual sugar, pH, titratable acidity, acetic acid, and free and total sulfur dioxide. Forty-three volatile compounds (alcohols, esters, acids, terpenes, aldehydes, aromatic hydrocarbons, etc.) were tentatively identified using a nontargeted HS-SPME-GC-MS method. Ethyl octanoate, phenylethyl alcohol, ethyl decanoate, and ethyl acetate were the most relatively abundant volatile compounds across the sample set. A trained panel (n = 11) evaluated each mead using descriptive analysis and the chemical and sensory analyses were compared. Acidity, sweetness, and cloying and viscous mouthfeel sensations, and alcoholic heat were the most influential sensory attributes and were driven by titratable acidity, residual sugar, and ethanol content, respectively. Ethyl octanoate and ethyl decanoate were correlated with manure aroma, phenylethyl alcohol with yeast and green aromas, and ethyl acetate with citrus, solvent, and green olive aromas. This research further elucidates the empirical relationship between the chemical composition and sensory profiles of commercial meads. PRACTICAL APPLICATION: This work provides the mead industry with further understanding of the compositional drivers of the sensory profiles of commercial meads and demonstrates product categories (dry, semi-sweet, sweet) do not necessarily indicate compositional or sensory attributes.

Impact of Fermentation Processes on the Bioactive Profile and Health-Promoting Properties of Bee Bread, Mead and Honey Vinegar

Recently, an increasing interest is paid to bee products obtained as a result of the fermentation process. Some of them can be consumed directly (bee-collected pollen, honey, bee bread etc.), while others are the result of lactic and/or acid fermentation (honey vinegar and honey wine). Bee bread is the result of pollens’ lactic fermentation, whereas mead is obtained by honeys’ lactic fermentation. Moreover, as a result of honey acetic acid fermentation, honey vinegar is obtained. Sensory characteristics and aroma composition have been scarcely studied, which may depend on the starter culture and fermentation process. Along with the medicinal properties they are a vital resource for future researches as they are of particular importance in the food market. In this review, we discuss the aroma-active compounds, taste, and sensorial characteristics of fermented bee products along with the approaches that can be developed for the flavor improvement based on existing technologies. Furthermore, the beneficial effects on human health are also described, with special attention that should be attributed to finding the use of probiotics in these fermented products as health-promoting effects.

Preliminary study of the influence of mineral content on quality parameters of Jordanian-origin honey collected from different geographical regions

In this work, physicochemical properties of eight honey samples harvested from different regions over Jordan were investigated. Quality parameters including free acidity, pH, conductivity, 5-hydroxymethylfurfural (5-HMT) and diastase activity were monitored for freshly harvested samples and during storage time over 24-month. The level of minerals (Na, K, Mg, Ca, Fe, Ni, Cu, Hg, Pb and As) in samples were quantified and found to be highly variable. The combined mineral content in the collected honeys was following the trend: multi-floral-Madaba (275.17 mg/kg) < multi-floral-Southern Shouna (600.83 mg/kg) < Centaurea iberica-Irbid (654.42 mg/kg) < Ziziphus Spina Christi-Al-Ghour (747.14 mg/kg) < Urginea maritima-Petra (752.52 mg/kg) < Echinopspolyceras-Karak (830.41 mg/kg) < Eucalyptus-Al-Azraq (1117.1 mg/kg) < multi-floral-Jerash (2297.57 mg/kg). As indicated from the trend, the mineral content in multi-floral-Jerash was notably high even when compared with international values. Harmful elements such as Cu, Hg, Pb and As were not detected providing higher nutritional value for the local honey. For fresh honeys, analysis revealed that samples rich with minerals have lower moisture, higher acidity, lower pH, and lower diastase activity. After 24-month storage, samples of higher minerals manifested higher values of 5-HMF and this supported that minerals would speed up glucose conversion.

Comparison of Physicochemical, Microbiological Properties and Bioactive Compounds Content of Grassland Honey and other Floral Origin Honeys

The aim of this study was to compare the physicochemical, the microbiological, and the antioxidant characteristics of unifloral honey, polyfloral honey, honeydew, and hay meadows honey. Hay meadow is type of semi-natural grassland with a great floral diversity, an important resource for pollinators. Grasslands are the source of the spring nectar honey obtained in May and June. Water content, sugars (fructose, glucose, sucrose, trehalose, melezitose, maltose, erlose, turanose, and raffinose), electrical conductivity, phenolic content (gallic acid, protocatechuic acid, 4-hydrxybenzoic acid, vanilic acid, chlorogenic acid, caffeic acid, p-coumaric acid, rosmarinic acid, myricetin, quercitin, luteolin, kaempferol), color, viscosity, and microbiological characteristics were performed for all samples of honey. The total polyphenols content was significant for grassland honey (21.50 mg/100 g) and honeydew (30.49 mg/100 g) and less significant for acacia (0.08 mg/100 g) and rape honey (0.14 mg/100 g). All samples were microbiologically safe, and standard plate count (SPC) values were <10 cfu/g for all the samples, but the grassland honey had the highest microbiological quality: 33.3% of samples without microorganisms, 50.0% with the presence of yeast under limit, and 16.7% with yeast and mold under limit, a situation that does not meet other types of honey. The results of statistical analysis obtained with principal component analysis (PCA) showed a major difference between the grassland honey and the other types of honey.

Effect of different starter cultures on chemical and microbial parameters of buckwheat honey fermentation

The aim of this study was to analyze the microbiology of buckwheat honey fermentation inoculated with different starter cultures by culturing and PCR-DGGE, taking as a model for comparison a spontaneously fermented batch. The inoculants tested were (i) cider lees (from a cider factory), (ii) sourdough (from a bakery), and (iii) a commercial Saccharomyces cerevisiae strain. The results of the culturing and culture-independent techniques agreed well and detected the same dominant species along the fermentations. Our results suggest that S. cerevisiae strains, which constituted a majority population in all batches including the uninoculated one, carried out the fermentations. The highest microbial diversity was found at the beginning of the fermentation in the uninoculated batch; this contained in addition to S. cerevisiae bacteria (Paracoccus sp., Staphylococcus sp., and Bacillus sp.) and yeast (Candida sp.) species. Candida sp. was also common in batches inoculated with sourdough and cider lees cultures. Lactobacillus species were found throughout the fermentation of the sourdough-inoculated batch. Basic chemical analysis and testing trials demonstrated that the overall sensory acceptance of the four meads were highly similar. Yeast and bacteria isolated in this study could serve as a source of technologically relevant microorganisms for mead production.

Effects of Mead Wort Heat Treatment on the Mead Fermentation Process and Antioxidant Activity

The effects of mead wort heat treatment on the mead fermentation process and antioxidant activity were tested. The experiment was conducted with the use of two different honeys (multiflorous and honeydew) collected from the Lower Silesia region (Poland). Heat treatment was performed with the use of a traditional technique (gently boiling), the more commonly used pasteurization, and without heat treatment (control). During the experiment fermentation dynamics were monitored using high performance liquid chromatography with refractive index detection (HPLC-RID). Total antioxidant capacity (TAC) and total phenolic content (TPC) were estimated for worts and meads using UV/Vis spectrophotometric analysis. The formation of 5-hydroxymethylfurfural (HMF) was monitored by HPLC analyses. Heat treatment had a great impact on the final antioxidant capacity of meads.

Developments in the fermentation process and quality improvement strategies for mead production

Mead is a traditional alcoholic drink derived from the fermentation of diluted honey in the presence of appropriate yeast. Its modern production, in general terms, involves the addition of nutrients to initial diluted honey, pasteurization, yeast inoculation, fermentation and removal of impurities. Undesirable events along the process have been reported; among them, we highlight: delayed or arrested fermentations, modified and unpleasant sensory and quality parameters of the final product. These problems have been linked to the inability of yeasts to accomplish their role in extreme growth conditions. Emphasis has also been placed on the long fermentation times required, ranging from weeks to months, particularly when traditional procedures are applied and when the honey concentration is low. A series of alterations to the must and technological changes have been proposed in order to optimize the mead production process. In this context, this review examines the evidence that aims to improve meads' quality and make the production process easier and more efficient, by clarifying the source of unexpected events, describing the implementation of different fermentative microorganisms and using new methodologies.

Effects of harvesting methods on physicochemical and microbial qualities of honey

Honey harvesting is accomplished using two main methods: traditional and modern methods; the former involves the use of naked flames to rid off or even destroy honey bees, while the latter involves use of smoke to suppress bees' aggressiveness. This research work investigated the effect of the method of harvesting on the quality of honey. The quality attributes investigated include: colour, total solids, viscosity, pH, diastase activity, acidity, sugars, ash, nitrogen, total antioxidants, hydroxymethylfurfural (HMF) content and microbial properties. The results revealed that the honey samples harvested using modern harvesting method had better quality in terms of ash content, total antioxidants, diastase activity, colour, sugars and microbiological attributes. The lower quality of honey harvested using traditional method could be attributed to the adverse effect of the burning during traditional harvesting on the quality of the honey. It is therefore concluded that modern method of harvesting honey produces better quality of honey and should be encouraged.

Mead production: tradition versus modernity

Honey is a natural product with recognized physical and chemical properties, which contribute to its biological activity. However, honey is currently being sold at low prices, making it imperative to find alternatives to make apiculture a viable national enterprise. One of these alternatives could be mead production. Despite the excellent properties of honey, mead production faces several problems, namely, delays and "pouts" fermentations, lack of product uniformity, and production of yeast off-flavors. Many factors might be related with these problems, such as honey variety, temperature, medium composition (vitamin and nitrogen content), fermentative yeast, and pH. Due to all these factors, mead production has decreased over the years. To overcome this situation, more research is needed to optimize the production of this beverage. This chapter presents a comprehensive review of previous research on mead production. It will focus on honey characterization and mead production. The first section covers honey composition and the way this affects honey properties, as well as important parameters that are indicators of honey quality. The second section discusses mead production, including fermentative microorganisms, fermentation conditions, and required postfermentation adjustments and maturation conditions. The final section focuses on the problems that must be surpassed and what the future holds for mead production.