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Nutritional value, vitamins, sugars and aroma volatiles in naturally fermented and dry kvass

  • Latvia University of Life Sciences and Technologies (former Latvia University of Agriculture)
Ivo Lidums*, Daina Karklina, Asnate Kirse, Martins Sabovics
Department of Food Technology, Faculty of Food Technology, Latvia University of Agriculture, 22 Rigas iela, Jelgava, Latvia,
Naturally fermented rye bread kvass is a seasonal product with a pronounced rye bread flavour having the highest demand during hot
summer days. However, non-pasteurised and non-filtered kvass has a very short shelf-life. There are numerous benefits of drying to
extend kvass shelf-life, however it can have a significant influence on the product composition and quality. The aim of this research
was to assess and compare nutritional value, vitamins, sugars and aroma volatiles in naturally fermented and spray dried kvass.
Naturally fermented non-pasteurised, non-filtered bread kvass was used to produce dry kvass at the University of Warmia and Mazury
in Olsztyn, Poland. Maltodextrin was used in 25% quantity to kvass dry matter in order to aid the spray drying process. Nutritional
value of liquid kvass (7% solids) and dry kvass (powder, 93% solids) was determined according to EU Regulation 1169/2011,
B vitamins according to AOAC 986.27 (B1), AOAC 970.65 (B2) and AOAC 961.14 (B3). Content of sugars was determined using
high performance liquid chromatography, whereas aroma volatiles were assessed using solid phase microextraction in combination
with gas chromatography/mass spectrometry. Drying process had a significant influence on the content of B vitamins in kvass; the
highest decrease was observed for niacin (vitamin B3). The content of major sugars was lower in dry kvass based on the dilution by the
addition of maltodextrin. Totally 26 different volatile compounds were detected in liquid and dry kvass, total values of peak areas were
significantly lower in dry kvass (p<0.05).
Keywords: kvass, spray drying, micronutrients, volatile compounds.
Soft drinks are in the diet of consumers throughout their
lives, and the choice of the product depends on the taste
of the drink, its impact on the health, national traditions
and market trends. Kvass is a non-alcoholic beverage
that can be used without restriction, as its effects on the
human body are similar to kefir; furthermore, the energy
value of naturally fermented kvass is approx. ½ less than
of typical non-alcoholic beverages (Lidums et al., 2014).
Due to the favourable microflora composition (lactic
acid bacteria, yeast), kvass is enriched with B vitamins,
lactic acid and carbon dioxide which is a product of
incomplete alcoholic and lactic acid fermentation
(Omasheva et al., 2015).
Naturally fermented non-pasteurised and non-filtered
rye bread kvass is a seasonal product with a pronounced
rye bread flavour and a very short shelf-life. Similar to
dry juices (juice powders), the benefits of drying to
extend kvass shelf-life are reduced volume or weight,
less packaging, easier handling and transport. Therefore,
dry naturally fermented kvass could be a valuable
contribution in comparison with liquid kvass. There are
several drying methods, but spray drying is one of the
techniques used to produce dry powders. Spray drying
is the transformation of the substance of the liquid or
slurry to dry powdery substance. The liquid product is
atomized into a chamber where the resulting spray
mixes with hot gas, which evaporates the liquid
component of the spray leaving dried particles (Goula,
Adamopoulos, 2010). Drying, however, can have a
significant influence on the product composition and
quality, thus, it is important to investigate the effect of
drying technological processes.
Recently Lidums and Karklina (2016) investigated the
possibilities of dry kvass application in food flavour
enrichment and concluded that milk candy ’Gotiņa’, ice-
cream ‘Plombir’, biscuits, meringue cookies, éclair
filling and cupcakes can be supplemented with dry kvass
with good sensory and physico-chemical outcomes.
The aim of this research was to assess and compare
nutritional value, vitamins, sugars and aroma volatiles in
naturally fermented and spray dried kvass.
Materials and Methods
Experimental design
The object of the research was liquid and dry kvass.
Kvass samples were analysed at:
o Latvian Certification centre, Ltd. nutritional value
of kvass,
o Institute of Biology, University of Latvia content
of B vitamins,
o Department of Chemistry, Latvia University of
Agriculture content of sugars,
o Department of Food Technology, Latvia University
of Agriculture aroma volatiles.
Naturally fermented non-pasteurised, non-filtered bread
kvass from Liepzeme Ltd. (water, rye bread rusks 10%
(rye flour, wheat flour, sugar, rye malt, salt, yeast, barley
malt extract, caraway), sugar, barley malt, wheat
malt, acidifier: citric acid, yeast) was used to
produce dry kvass by spray drying as described by
Lidums et al. (2016). Dry kvass was obtained at the
Institute of Process Engineering and Equipment, The
University of Warmia and Mazury in Olsztyn, Poland.
Kvass was atomized from a rotary atomizer (disk speed
11 000 rpm) into a vertical co-current drying chamber
with inlet and outlet air temperatures of 170 °C and
103 °C, respectively; temperature inside the drying
chamber was 7580 °C. Maltodextrin was used in 25%
quantity to kvass dry matter in order to aid the spray
drying process.
DOI: 10.22616/foodbalt.2017.027
Determination of nutritional value and calculation of
energy value
Nutritional composition of liquid and dry kvass samples
was determined according to standard methods: protein
content (ISO 5983-1:2005), fat and saturated fatty acid
content (ISO 12966-4:2015), sugar content by
Bertrand's method (Chidan et al., 2011), sodium content
(ISO 7485:2000), ethanol content (ГОСТ 6687.7-88)
and moisture content (ISO 5537:2004). Carbohydrates
(%) were determined by difference (FAO, 2003)
according to formula:
𝐶 = 100 (𝑚 + 𝑝 + 𝑙 + 𝑎), (1)
where C carbohydrates, %, m moisture content,
p protein content, %, l lipid content, %, a ash
content, %.
Energy value of liquid and dry kvass samples was
calculated according to coefficients described in
EU Regulation No 1169/2011: carbohydrates 17 kJ g-1;
protein 17 kJ g-1, fat 37 kJ g-1 and ethanol 29 kJ g-1.
Determination of B vitamins
Vitamin B1 was determined by the fluorometric method
(AOAC 986.27), which is based on the oxidation of
thiamine to thiochrome, followed by measurement of
fluorescence intensity. Vitamin B2 was determined by
the fluorometric method (AOAC 970.65), which is
based on fluorescence measurement of riboflavin after
acid and enzymatic hydrolysis. Vitamin B3 was
determined by the colorimetric method (AOAC 961.14),
which is based on the König reaction with cyanogen
Determination of sugar content
The content of fructose, glucose and maltose was
determined using high performance liquid
chromatography (HPLC) method (Shimadzu LC 20
Prominence) according to Lidums et al. (2016).
Identification of sugars in liquid and dry kvass was done
by comparing retention times of individual sugars in the
reference vs. tested solution (qualitative analysis).
Detection of aroma volatiles
Volatile compounds were determined in liquid and dry
kvass samples using solid phase micro-extraction
(SPME) in combination with gas chromatography/mass
spectrometry (GC/MS) according to the method
described by Lidums et al. (2015). The SPME fibre was
coated with a thin bipolar polymer film
Carboxen/Polydimethylsiloxane (CAR/PDMS). The
film thickness was 85 μm with bipolar polarity (Supelco,
Inc., USA). The process consisted of heating the
samples to release volatile compounds above the liquid
phase and absorb them onto the CAR/PDMS fibre. Then
volatile compounds from the fibre were thermally
desorbed in GC/MS injector and transferred to
the capillary column for separation. Compounds were
identified by comparison of their mass spectra with mass
spectral library Nist98 and the amount of compounds
was measured as peak area units (PAU).
Data analysis
The obtained data processing was performed with the
Microsoft Excel 13 for Windows; mean values and
standard deviations were calculated. t-test and Tukey’s
test were used for data cross-comparison. For the
interpretation of the results it was assumed that α=0.05
with 95% confidence.
Results and Discussion
The characteristics of naturally fermented non-
pasteurised and non-filtered rye bread kvass were
evaluated in two products liquid and dry form of kvass.
Kvass and similar products have been produced before,
whereas dry kvass was produced and investigated for the
first time. The comparison was carried out on dry weight
basis, except for nutritional composition and aroma
Nutritional value of naturally fermented and dry kvass
Dry kvass had a higher energy value than naturally
fermented kvass on fresh weight basis (Table 1). Dry
kvass contains only traces of ethanol contrary to kvass,
as alcohol evaporates during drying process (USDA
Table of Nutrient Retention Factors).
Table 1
Nutritional and energy value of
naturally fermented and dry kvass
Dry matter, %
Protein content, g 100 g-1
Fat content, g 100 g-1
of which saturates, g 100 g-1
Carbohydrate content, g 100 g-1
of which sugars, g 100 g-1
61.30 ±0.15
Sodium content, mg 100 g-1
Ethanol content, vol %
Energy value, kJ 100 g-1
B vitamins in naturally fermented and dry kvass
Drying process had a significant influence on the
content of B vitamins in kvass (Table 2); the highest
decrease was observed for niacin (vitamin B3).
Table 2
Content of B vitamins in kvass samples,
mg 100 g-1 DW
Liquid kvass
Dry kvass
Thiamine (B1)
Riboflavin (B2)
Niacin (B3)
A kinetic analysis of the thermodegradation process on
B vitamins showed that these vitamins are thermolabile
(Fuliaş et al., 2014), and the decrease after thermal
processing can account to 60% (Asadullah et al., 2010).
Several authors have reported the reduction of
water-soluble vitamins after spray drying
(Grabowskia et al., 2008; Abubakar, Jega, 2010),
besides the addition of maltodextrin decreased the
overall kvass solids together with the amount of B
vitamins in dry kvass.
Sugar content in naturally fermented and dry kvass
Major sugars in kvass were fructose and glucose, both
kvass samples also contained significant amount of
maltose (Table 3). The content of major sugars was
higher in liquid kvass. Barba et al. (2014) showed that
drying process caused a significant decrease in the
reducing sugars content which was associated with
Maillard’s reactions. However, Grabowskia et al. (2008)
reported that spray dried sweet potato powder with the
addition of maltodextrin showed lower content of sugars
compared to sweet potato puree, based on the dilution
by the addition of maltodextrin.
Table 3
Sugars in kvass samples, g 100 g-1 DW
Liquid kvass
Dry kvass
Therefore, we conclude that the decrease of fructose,
glucose and maltose in dry kvass can be accounted to the
addition of maltodextrin as drying aid, which increases
glass transition temperature and improves product
stability (Tonon et al., 2011; Oberoi, Sogi, 2015).
Aroma volatiles in naturally fermented and dry kvass
A total of 26 different aroma volatile compounds were
isolated and characterized by GCMS analysis. The
identified volatile compounds belong to esters, alcohols,
acids, aldehydes and ketones. A more various volatile
compound profile was found for naturally fermented
kvass. 19 volatile compounds were identified in
naturally fermented kvass with the total sum of peak
area 19.16×107 PAU. The total sum of peak area
(11.81×107 PAU) in dry kvass was approx. 40% lower
than in liquid kvass (p<0.05), a total of 15 volatile
compounds were present in dry kvass (Table 4). The
highest value of peak area (10.05×107) among all
detected volatile compounds was detected for 4-penten-
2-ol (alcohol) in naturally fermented kvass, which gives
fruity aroma, which is in agreement with a previous
research by Lidums et al. (2015), whereas in dry kvass
the amount of 4-penten-2-ol was about 7 times lower.
Carvone had the second highest peak area (2.28×107) in
naturally fermented kvass, but it was not present in dry
kvass. According to Sedláková et al. (2003), carvone
and limonene form the main portion of essential oils in
caraway fruits, which are an ingredient in the rye
bread used for naturally fermented kvass production.
Salim et al. (2015) reported that drying affected the
reduction of carvone in spearmint.
A significant amount of ethyl octanoate (1.03×107) was
found in naturally fermented kvass, resulting in fruit and
fat odour. The three aroma volatiles with the highest
peak area values in dry kvass were hexanal,
4-penten-2-ol and benzaldehyde, forming green, fruity,
bitter and almond odours, respectively.
Volatile compounds found in both liquid and dry kvass
samples form base aroma profile which includes fruity
(4-penten-2-ol), green (hexanal), sour (acetic acid),
bread, almond, sweet (furfural), burnt (furfuryl alcohol),
fatty type (hexanoic acid), floral type (benzylalcohol),
rose (phenylethylalcohol), sweat, cheese (octanoic acid)
aroma. Table 4
Volatile compounds (PAU×107) in liquid and
dry kvass samples
peach, fatty
butter, cream
Acetic acid
Furfuryl alcohol
Hexanoic acid
fatty type
floral type
Octanoic acid
sweat, cheese
Ethyl decanoate
waxy type
Decanoic acid
rancid, fat
rose, honey,
malt, burnt
Isoamyl acetate
Ethyl caproate
fruity, green,
Hexyl acetate
sweet, fruity
Heptyl acetate
Ethyl octanoate
fruit, fat
The sum of peak areas
*Gas chromatography - olfactometry of natural products
(2004); Odor Descriptors (2015)
Volatile compounds found in kvass samples are
associated with the roasting of geminated grains (malt
production), bread baking and the metabolism of yeast
cells during fermentation process as argued by
Hazelwood et al. (2008), Purlis (2010), Birch et al.
(2013) and Riu-Aumatell et al. (2014).
Dry kvass had a higher energy value than naturally
fermented kvass. Spray drying had a significant
influence on the decrease of B vitamins in dry kvass
(p<0.05); the highest decrease was observed for niacin
(B3). The content of major sugars was lower in dry kvass
based on the dilution by the addition of maltodextrin.
26 different volatile compounds were detected in liquid
and dry kvass, total values of peak areas were
significantly lower in dry kvass (p<0.05). However, the
profile of aroma volatiles in dry kvass demonstrates that
it can be used for food flavour enrichment.
The authors would like to thank Fabian Dajnowiec,
Department of Food Science; University of Warmia and
Mazury in Olsztyn, for valuable assistance during dry
kvass production.
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... Opposite to VACs connected with fermentation, in this group almost every compound had significantly higher content in LTSD than HTSD variants (2-pentylfuran was an exception). Similar result of decreased concentration of VACs after spray drying was presented i.e. for spray dried kvass (Lidums, Karklina, Kirse, & Sabovics, 2017), cocoa liquor nanoemulsion (Calva-Estrada et al., 2019), wine (Avellone et al., 2018). On the other hand, observed the increased content of VACs after spray drying of honey at low temperature. ...
Sugarcane molasses was chosen as an example material for the investigation of the influence of spray drying approach (conventional high temperature and a developed low temperature drying method which applies dehumidified air as a process gas) and the presence of drying carrier on volatile aroma compounds (VACs). Among 28 identified VACs 10 were chosen for detailed investigation. The influence of drying depended, apart from two mentioned factors, also on the type/origin of VACs and particle morphology. In the case of compounds connected with the fermentation process, the retention was higher after high temperature spray drying. On the contrary, VACs which could be additionally created during spray drying, thus Maillard reaction and caramelization reaction products, were more abundant in samples dried at lower temperature. As was explained, this contradictory phenomenon could be related to the higher evaporative loss at higher temperature, and also the fact that particles created at higher temperature were partially destroyed (as evident from the SEM photos). The presence of carrier increased the content of VACs after low temperature spray drying, which was connected to the encapsulation mechanisms of high molecular weight material. Thus, the most beneficial was the simultaneous application of carrier and low temperature spray drying approach.
Cereal grains constitute major source of carbohydrates, proteins, B-complex vitamins, vitamin E, fiber, and micronutrients. Traditionally, fermentation was the simple and inexpensive technique to increase the shelf-life, organoleptic properties, nutritional attributes, and functional qualities. Cereal fermentation was started with leavening wheat dough with yeast by ancient Egyptians and souring cereal-legume batters by ancient Indians. Fermentation of cereal grains leads to reduce the amount of nondigestible poly and oligosaccharides, helps in synthesis of some essential amino acids and increase in the level of vitamin B complex. It also creates optimum pH for degradation of antinutritional compounds in the cereals such as phytates, which may improve the bioavailability of soluble iron, zinc, and calcium in several folds. In recent times, evolvement of functional food era demands significant transformation in the field of nutritional sciences using sophisticated technological tools for fermentation, which will provide foundation for development of safe food products with unique nutritional and functional attributes. Therefore, objective of the book chapter is to summarize some of the indigenous fermented foods and beverages produced world-wide and recent technological interventions to commercialize these products to meet the emerging needs of people all over the world.KeywordsCereal grainsFermentationFunctional foodShelf lifeNutritional attributes
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The authors considered the possibility of expanding the assortment of fermented beverages in small beer production enterprises. As a new type of product, the production of kvass with plant extracts is proposed: pot marjoram, clary sage, lemongrass, Schisandra chinensis. Investigations of their physicochemical properties, aroma and antioxidant activity were carried out. It was noted that the highest content of antioxidants in the extracts of pot marjoram and Schisandra chinensis was 18.34 and 12.36 mg/dm 3. Fermentation of kvass wort was carried out with yeast Sacharomyces cerevisiae of strains ICV D 254, EC-1118, 71B- 1122, V 116 at a temperature of 28 ° C within 9 hours. The result of the analysis of solids wort’s and acidity dynamics during the fermentation process is a recommendation the EC-1118 strain. Four kvass recipes with different functional orientations have been developed. During the research, the method of mathematical planning and statistical processing of the results was used. When optimizing the parameters, the influence of the fermentation temperature, the dosage of plant extracts and the dosage of yeast on the acidity of the wort is considered. It has been established that the dosage of plant extract has the greatest effect on the acidity of kvass.
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Kvass is a non-alcoholic beverage produced by fermenting kvass mash with yeast; alcohol content in kvass must be less than 1.2% by volume. Kvass extracts have longer shelf-life and they are essentially free of ethanol. The aim of this research was to evaluate and compare aroma compounds in naturally fermented kvass and kvass extracts. Experiments were carried out at the Latvia University of Agriculture, Department of Food Technology from November 2014 to February 2015. Three commercially available kvass samples (Bruveris, Bauskas and Liepkalni) were used to produce kvass extracts applying vacuum evaporation. The investigation of volatile compounds in kvass and kvass extracts was performed using solid phase microextraction and gas chromatography mass spectrometry. Dry matter content in kvass extracts was 32.4 ± 0.3% (ISO 2173:2003). In all kvass and extract samples in total 25 volatile compounds were detected. Ten of them were esters, five alcohols, five acids, four aldehydes and three ketones. Such aroma compounds as ethyl acetate (fruity flavour), hexyl acetate (fruit, herb) and ethyl decanoate (grape) were found only in Bruveris kvass, 2,3-butanedione (buttery) and phenethyl butyrate (floral) were found only in Bauskas alus kvass and three volatile compounds were identified only in Liepkalni kvass – acetic acid (sour), furfuryl alcohol (burnt) and carvone (caraway). Less than a half of the main aroma volatiles in kvass were also identified in kvass extracts and total values of peak areas were significantly lower in kvass extracts compared to kvass (p=0.01).
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The experiment was investigated the effect of drying method on carvone and spearmint oil composition. Spearmint (Mentha spicata var. Viridis) plants were raised from underground runners obtained from fully mature plants. Spearmint samples were dried under different conditions till the weight of mint herb reached 20% of its fresh weight. The treatments were; shade drying under ambient conditions, sun drying, under direct sun shine, forced – air oven drying at 60 oC, forced-air drying at 70 oC and forced-air oven drying at 80 oC. Oil was extracted by water distillation according to British Pharmacopoeia technique. Oil composition was analyzed by GC/MS. The result showed that Carvone [2-cyclohexen-1-one, 2-methyl-5- (1-methylethenyl)-, (R)] was significantly highest in forced-air oven drying (78.33% - 82.06%), followed by sun-drying (73.34%) and the least in shade drying at ambient temperature (69.65%). Oven drying at 60°C yielded highest carvone content (82.06%) followed by 70°C (78.99%) and lastely 80°C (78.33). The results indicated that some spearmint constituents such as Neodihydrocarveol and Alpha – pinene were only formed in samples dried under direct sun shine and at high oven-drying temperature, some increased with an increase in drying temperature and others like Alpha – cubebene only formed in shade and at low drying temperature. Index terms: Spearmint oil composition, Carvone, Shade, Sun and oven drying.
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The effects of microwave assisted drying on banana fruit was evaluated. Water, reducing sugars, and polyphenol contents, as well as poly-phenol-oxidase activity were evaluated along the radial and axial positions in thick slices of banana, according to a properly defined cutting and assaying protocol. The effects of the microwave-assisted drying process were compared to the convective air-assisted drying resulting faster than the conventional process. In particular, the resulting samples were homogeneous in the water content; the contents of reducing sugars were strongly decreased on drying with microwaves; the poly-phenol-oxidase was inactivated by the high temperature produced by the process and thus the polyphenols content remained practically the same as in the fresh product.
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Caraway fruits contain 1 - 6 % of essential oils consisting of about 30 compounds, from which carvone and limonene account from the main portion, about 95 %. To evaluate the quality of various caraway cultivars, the amounts of essential oils and the carvone / limonene ratio was measured. The most common method of essential oil evaluation is the steam distillation in accordance with Standard ČSN 58 0110, but an alternative method - supercritical fluid extraction (SFE) - was also investigated in this paper. Ground caraway fruits were extracted under different SFE conditions (pressure, temperature, use of modifiers). Released compounds (carvone and limonene) were quantified by GC.
Abstract The effect of spray/freeze drying and maltodextrin concentration (3%, 5%, 7% and 10%) on pigment retention of watermelon juice powder from three cultivars was investigated. Incorporation of maltodextrin in watermelon juice yielded freely flowable powder. The spray dried powder has less moisture content, low water activity, high dissolution value and less reducing sugar content as compared to freeze dried powder. Lycopene of fresh watermelon juice was 4.58-6.53 mg/100 g on wet basis (wb) which was increased up to 56.4 mg/100 g (wb) in spray dried powder and 62.3 mg/100 g (wb) in freeze dried powder. Variation in instrumental color parameters with maltodextrin levels and dryers revealed that the freeze dried powder have lower 'L' value, higher 'a' value, higher 'b' value, lower 'hue angle' and high 'chroma' values as compared to spray dried powder. In spray drying lycopene loss was influenced by high air temperature and intensive exposure to oxygen causing degradation of lycopene. The freeze dried powder retained more pigment but powder had high water activity, limited shelf life, low flowability and hygroscopic in nature. Good correlation between colorimetric values and lycopene content was observed in spray dried powder.
Objective: This study was therefore undertaken to produce the spray-dried powders from the whole juices of the two plants and to comparatively evaluate the nutritional value of the powders and whole juices with a view to enhancing their utilization in Nigeria. Materials and Methods: Roselle (Hibiscus sabdariiffa) and Tamarind (Tamarindus indica) juices were extracted from the calyces and tamarind pulp respectively. Parts of the extracted juices were spray dried while the remaining parts were preserved as whole juices. The juices and powders were then analyzed for the nutritive composition and compared. The effects of the spray-drying on nutritional composition were evaluated. Results: The results indicated a significant decrease (P < 0.05) in the spray dried powders of both Roselle and Tamarind for the values of total carbohydrates, crude protein and lipids, phosphorus, vitamins C and A. Elemental analysis shows that sodium, magnesium and calcium were relatively stable to spray-drying, while potassium decreased in the spray-dried sample of Tamarin but not in the Roselle. Conversely, the level of iron in the spray-dried powders of Tamarind and Roselle increased by 20 percent and 27 percent respectively. Although, the process of spray-drying led to some nutrient losses in both tamarind and Roselle powders, the effect was not significantly adverse (P > 0.05). The micro nutrients notably vitamins C and A, iron and calcium usually sourced from beverages were not adversely affected. Conclusion: Spray-drying process can be employed to preserve these two juices at commercial level for wider and greater utilization of their products.
The consumers of today have an increasing interest in high quality bread with appealing aroma. The scope of this work is to investigate how aroma in wheat bread crumb is influenced by different fermentation conditions: amount of yeast (20, 40 and 60 g/kg flour) and fermentation temperature (5,15 and 35 degrees C). Dough samples were fermented to equal height and baked, and the aroma compounds from the bread were extracted by dynamic headspace extraction and analyzed by gas chromatography mass spectrometry. Quantification of the aroma compounds was performed by multiple headspace extraction. The most aroma active compounds identified were 3-methylbutanal, (E)-2-nonenal, 3-methyl-1-butanol, and 2,3-butanedione. Increasing the yeast concentration was found to increase formation of the majority of the compounds formed from the yeast metabolism, with 2,3-butanedione and phenylacetaldehyde as the most aroma active compounds. High fermentation temperature (15 and 35 degrees C) increased formation of many lipid oxidation compounds, with hexanal and heptanal having the highest odor activity values. Low fermentation temperature (5 degrees C) was found to increase formation of the three esters ethyl acetate, ethyl hexanoate, and ethyl octanoate, with ethyl hexanoate having the highest odor activity value. The odor activity values of the esters were generally low.
The thermal behaviour of vitamins B-1, B-2 and B-6 under non-isothermal conditions and dynamic air atmosphere was studied. According to our study, it was determined that the most stable compound is vitamin B-2. A kinetic analysis of the thermodegradation process using four different data processing methods (Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and modified NPK) was performed. The NPK was the only method that made it possible to evaluate the contribution to the reaction rate of the temperature and conversion, respectively. The results obtained from kinetic analysis were corroborated with the molecular architecture of the studied compounds.
The volatile profile of low-alcohol and alcohol-free beers were compared with that of alcoholic ones. Qualitative and quantitative differences were analysed by Headspace Solid-Phase Microextraction coupled to Gas Chromatography - Mass Spectrometry (HS-SPME-GC-MS). Fermentation compounds as esters (isoamyl acetate, ethyl hexanoate, ethyl octanoate), alcohols (1-octanol, decanol, isobutanol, isoamyl alcohol) and fatty acids (hexanoic and octanoic acid) were present in higher quantities in alcoholic beers. The low-alcohol beers were characterized by compounds derived from malt and the roasting process, including pyrazines and furanes, and volatile compounds such as linalool, β-humulene and α-terpineol derived from the essential oil of hops. Benzaldehyde, acetylpyrrole, furfural and 2-furanmethanol were characteristics of free-alcohol beers.
A new technique for spray drying concentrated orange juice using dehumidified air as drying medium and maltodextrin as drying agent was developed. A pilot-scale spray dryer was employed for the spray drying process. The modification made to the original design consisted in connecting the dryer inlet air intake to an absorption air dryer. 21 DE, 12 DE, and 6 DE maltodextrins were used as drying agents. Concentrated orange juice was spray dried at inlet air temperatures of 110, 120, 130, and 140°C and (concentrated orange juice solids)/(maltodextrin solids) ratios of 4, 2, 1, and 0.25. Data for the residue remaining on the walls were gathered and the powders were analyzed for moisture content, bulk density, rehydration, hygroscopicity, and degree of caking. The combination of maltodextrin addition and use of dehumidified air was proved to be an effective way of reducing residue formation.