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

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FOODBALT 2017
NUTRITIONAL VALUE, VITAMINS, SUGARS AND AROMA VOLATILES
IN NATURALLY FERMENTED AND DRY KVASS
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,
*e-mail: ivo@ilm.lv
Abstract
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.
Introduction
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 75–80 °C. Maltodextrin was used in 25%
quantity to kvass dry matter in order to aid the spray
drying process.
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DOI: 10.22616/foodbalt.2017.027

FOODBALT 2017
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
bromide.
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
volatiles.
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
Parameters
Liquid
kvass
Dry
kvass
Dry matter, %
7.00±0.02
93.00±0.04
Protein content, g 100 g-1
0.15±0.02
1.90±0.10
Fat content, g 100 g-1
<0.10
<0.10
of which saturates, g 100 g-1
<0.01
<0.10
Carbohydrate content, g 100 g-1
5.90±0.02
75.20±0.21
of which sugars, g 100 g-1
4.70±0.02
61.30 ±0.15
Sodium content, mg 100 g-1
0.16±0.01
2.10±0.05
Ethanol content, vol %
1.20±0.03
<0.10
Energy value, kJ 100 g-1
130.40
1285.77
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
Vitamins
Liquid kvass
Dry kvass
Thiamine (B1)
0.71±0.09
0.25±0.02
Riboflavin (B2)
1.28±0.12
0.48±0.02
Niacin (B3)
18.14±0.48
4.36±0.12
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
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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
Sugars
Liquid kvass
Dry kvass
Fructose
25.13±0.19
15.83±0.12
Glucose
21.76±0.14
14.31±0.17
Maltose
8.26±0.11
6.12±0.07
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 GC–MS 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
Volatile
compounds
Odour*
Liquid
kvass
Dry
kvass
4-penten-2-ol
fruity
10.05
1.39
Hexanal
green
0.59
3.04
3-methyl-butanal
chocolate,
peach, fatty
–
0.10
2-pentylfuran
fruity
–
0.68
1-pentanol
fermented
–
0.17
3-hydroxy-2-
butanone
butter, cream
–
0.22
1-octen-3-ol
mushroom
–
0.50
Acetic acid
sour
0.58
0.98
Furfural
bread,
almond,
sweet
0.03
0.62
Benzaldehyde
bitter,
almond
–
1.56
Furfuryl alcohol
burnt
0.17
0.72
Hexanoic acid
fatty type
0.07
0.41
Benzylalcohol
floral type
0.55
0.66
Phenylethyl
alcohol
rose
0.26
0.35
Maltol
caramel
–
0.21
Octanoic acid
sweat, cheese
0.30
0.21
Carvone
caraway
2.28
–
Ethyl decanoate
waxy type
0.60
–
Decanoic acid
rancid, fat
0.19
–
2-phenylethyl
acetate
rose, honey,
tobacco
0.59
–
3-methyl-1-
butanol
whiskey,
malt, burnt
0.70
–
Isoamyl acetate
banana
0.63
–
Ethyl caproate
fruity, green,
pineapple,
sweet
0.28
–
Hexyl acetate
sweet, fruity
0.12
–
Heptyl acetate
green
0.05
–
2-ethyl-1-decanol
–
0.08
–
Ethyl octanoate
fruit, fat
1.03
–
The sum of peak areas
19.16
11.81
*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
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Hazelwood et al. (2008), Purlis (2010), Birch et al.
(2013) and Riu-Aumatell et al. (2014).
Conclusions
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.
Acknowledgment
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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