INFLUENCE OF PARTIAL SUBSTITUTION OF SUGAR WITH SERENDIPITY BERRY (DIOSCOREOPHYLLUM
CUMMINSII) EXTRACT ON THE QUALITY ATTRIBUTES AND SHELF-LIFE OF WHEAT BREAD
Rowland Monday Ojo Kayode*1, Olufunmilola Adunni Abiodun1, Sarafa Adeyemi Akeem2, Halimat Omodasola Oyeneye1
Address(es): Dr. Rowland Monday Ojo Kayode
1
Division of Food Processing, Preservation, Microbial Biotechnology and Safety, Department of H ome Economics and Food Science, University of Ilorin, Nigeria,
+2348035850545.
2
Department of Food Technology, Faculty of Technology, University of Ibadan, Ibadan, Oyo State, Nigeria, +2347039314405.
*Corresponding author: kayodermosnr@gmail.com; rowland@unilorin.edu.ng
doi: 10.15414/jmbfs.2019.9.1.115-120
ARTICLE INFO
ABSTRACT
Received 29. 4. 2018
Revised 15. 3. 2019
Accepted 21. 3. 2019
Published 1. 8. 2019
Serendipity berry (Dioscoreophyllum cumminsii) contains a protein sweetener termed monellin which could be substituted for sugar in
foods for diabetics and dieters. Therefore, effects of partial substitution of sugar with serendipity berry extract on quality of white wheat
bread were investigated. The pasting properties of wheat flour treated with mixtures of 5 % sugar solution and serendipity berry extract
(100:0 control, 80:20, 70:30, 60:40, 50:50 and 40:60) were investigated. Wheat flour were blended with other ingredients and mixtures
of 5 % sugar solution and serendipity berry extract to form dough which were allowed to rise prior to baking. Chemical, microbiological
and sensory properties of the breads were evaluated. Pasting temperature, peak, final and setback viscosities of the control (sugar
solution treated-flour) and serendipity extract treated flour were significantly (p˂0.05) different. Moisture, ash, protein, fat, fibre and
carbohydrate contents of the breads ranged from 11.93–15.22 %, 0.75–3.06 %, 11.67–14.13 %, 4.29–9.06 %, 1.24–2.50 % and 55.01–
68.14 %, respectively. Although the bacterial (0.0–61 ×103 cfu/g) and fungal (2.0–76.0 ×103 cfu/g) counts of the breads increased
throughout the 5 days storage period, the serendipity berry extract exerted antimicrobial activities in the treated breads. The proximate,
except carbohydrate, of the breads increased while the bacterial and fungal counts decreased with increase in concentration o f the
serendipity extract. The 60 % serendipity extract treated-bread (mean sensory scores ≥ 8.0) compared favourably with the control (sugar
solution treated-bread). This study revealed that 60 % serendipity berry extract could be substituted for sugar for production of high
quality bread with extended shelf life.
Regular article
Keywords: Bread, Dioscoreophyllum cumminsii, Preservation, Quality attributes, Substitution, Wheat flour, Sweetener
INTRODUCTION
The ever increasing consumers' demand for wholesome and safe foods with
extended shelf-life and without the use of synthetic preservatives still remains a
major challenge to most food industries. The fruit, serendipity berry
(Dioscoreophyllum cumminsii), belonging to the family menispermaccae is an
unpopular and under-utilized tropical West African indigenous plant (Oselebe
and Nwankiti, 2005; Abiodun and Akinoso, 2014). It grows in humid and
heavily shaded understorey vegetation of closed forest towards the end of the
raining season usually between May and October (Abiodun et al., 2014). It is
regarded as a low acid food due to its high pH (6.6) and low titratable acid values
(Abiodun and Akinoso, 2014). Like many other fruits, serendipity berry has
high moisture content (80 %) (Abiodun and Akinoso, 2014) which makes it
highly perishable. It contains considerable amounts of carotenoids and its vitamin
C content has been reported to be higher than those of local orange, watermelon
and banana (Abiodun and Akinoso, 2014). Abiodun and Akinoso (2014) have
reported that the fruit contains low quantities of sugars (fructose, glucose and
fructose) and alkaloids (solasodine, tomatidenol and soladulcidine) with fructose
and soladulcidine being the major sugar and alkaloid, respectively. The intense
sweetness of serendipity berry has been attributed to a protein called monellin
(Inglett, 1976) which is mainly found in the mucilaginous mesocarp. This
protein is the sweetest known naturally occurring substance, up to 3,000 times
sweeter than sucrose, and approximately 100,000 times as potent as sugar on a
molar basis (Inglett and May, 1969, Faruya et al., 1983, Penarrubia et al.,
1992). Therefore, relatively lower concentrations of its extract may be required to
achieve desired sweetness and these have facilitated its recommendation for use
as a sugar substitute in foods for dieters and diabetics.
Bread is a widely consumed staple food which is mainly produced by baking
fermented dough of flour (usually hard wheat), yeast, salt, sugar and water. Other
ingredients that may be added include fat, milk and milk products, malt and malt
products, oxidants and improvers (such as ascorbic acid and calcium propionate),
surfactants and anti-microbial agents (Kučerová, 2015). Bread serves as one of
the most important sources of nutrients such as carbohydrate, protein, minerals,
fibre, and vitamins in the diets of many people worldwide (Correia et al., 2015).
Bread is an appealing, convenient and ready-to-eat food (Correia et al., 2015).
These attributes have led to a steady increase in its consumption in most parts of
the world including Nigeria. However, the shorter shelf life and perishability
nature of bread compared to most other bakery products poses a serious threat in
terms of economic loss to its producers as well as its marketers. After production
and during storage, bread swiftly loses its freshness and subsequently loses its
organoleptic qualities (Pateras, 1999; Ho et al., 2013). Generally, the changes in
chemical or physical properties that subsequently resulted in the reduction of the
crumb softness during storage time (staling), and spoilage, which result from
microbial attack are the two major factors that accelerate the rate of freshness
loss in bread (Pateras, 1999). Microbial spoilage of bakery products such as
bread is mainly attributed to the growth of moulds (Mentes et al., 2007) which
could result to substantial economic loss in the bakery sector and also posing
health challenges to consumers owing to the production of mycotoxins.
The detrimental health effects of sucrose-rich diets and consumers' demand for
safe products with extended shelf life and without chemical preservatives (Axel
et al., 2017), have prompted intensive search for plants with sweetening and
preservative properties. Recently, acceptable watermelon juice sweetened with
serendipity berry extract was reported to be microbiologically stable within the
twelve weeks of storage (Dauda et al., 2017). The present study was therefore
designed to determine the effects of using serendipity berry extract as sugar
substitute on the chemical, microbiological, sensory properties and shelf life of
wheat flour bread.
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MATERIALS AND METHODS
Materials
Fully matured serendipity berry was procured at Esa-Odo farm in Osogbo, Osun
state, Nigeria. White wheat flour (Dangote), refined sugar (sucrose), salt, instant
dry yeast and fats were procured from a local market (Oja-Oba) in Ilorin, Kwara
State, Nigeria. The materials were brought to the food processing laboratory of
University of Ilorin, Nigeria for processing and analyses. Distilled water was
used throughout the experiment and all reagents used were of analytical grade.
Extraction of juice from serendipity berry fruit
The serendipity berry juice was extracted as described by Dauda et al. (2017).
The serendipity berry fruits were washed with distilled water to remove dirt. The
thoroughly washed fruit was peeled and the seeds were removed. The juice
(sweetener) was extracted and strained through double layered muslin cloth to
obtain the fresh sweetener. The serendipity berry extract were measured with a
measuring cylinder into portions of 60 ml, 50 ml, 40 ml, 30 ml and 20 ml and
kept in the refrigerator at 4 ºC for further use.
Preparation of sugar solution
Five percent (5 %) sugar solution was prepared by dissolving 50 g of refined
sugar (sucrose) in 500 ml distilled water in a 1000 ml volumetric flask and then
made up to mark with distilled water. The solution was kept in the refrigerator at
4 ºC for further use.
baking pans and allowed to rise for 60 min at 30 °C. Loaves were baked for 10
min at 250 °C. The baked loaves were carefully removed from the pans and
allowed to cool and packaged in polyethylene bags for analyses. The flow chart
for the production of bread sweetened with serendipity berry extract is shown in
Figure 1. Figure 2 shows the bread samples produced.
Proximate composition of the bread samples
The moisture content was determined by AOAC (2000) method, while the ash,
crude protein, crude fat, crude fibre and carbohydrate contents of the breads were
evaluated using AOAC (1990). Briefly, the oven drying method at 105 oC for 5
hr was used for moisture determination. Protein content was determined using the
micro-Kjeldahl method for crude protein. Total ash was obtained by igniting 2 g
of sample at 600 oC for 2 hr using muffle furnace. Crude fat was determined by
soxhlet extraction with petroleum spirit as the solvent. Crude fibre was
determined using digestion method while carbohydrate was estimated by
difference [100-(% water + % protein + % fat + % ash + % crude fibre)].
Estimation of energy values of the breads
The energy values of the breads were estimated using Atwater factors in which
the percentage carbohydrate, crude fat and crude protein contents were multiplied
by 4, 9 and 4, respectively. The energy values of the breads were expressed in
kCal/g.
Pasting properties of serendipity berry extract-treated flours
In order to examine the effect of partial substitution of sugar with serendipity
berry extract on the pasting properties of wheat flour, six 25 ml of mixtures of 5
% sugar solution and serendipity berry extract (100:0, 80:20, 70:30, 60:40, 50:50
and 40:60) were prepared separately and their respective treated flour were coded
SSB0F, SSB2F, SSB3F, SSB4F, SSB5F and SSB3F. Pasting properties of the flour
samples were determined using a Rapid Visco Analyzer (RVA Model 3c,
Newport Scientific PTY Ltd, Sydney) as described by Arise et al. (2017) with
little modification. Briefly, 2.5 g of each flour sample was accurately weighed
into a previously dried empty canister and 25 ml of sugar solution or mixture of
sugar solution and serendipity berry extract was added. Samples were transferred
onto the water surface of the canister after which the paddle was placed into the
canister. The mixture was thoroughly mixed by the paddle fitted at the centre of
the canister and the canister was fitted into the Rapid Visco Analyzer. Peak
viscosity (RVU), Peak time (min), Peak temperature (℃), Trough (RVU),
pasting temperature (℃) and final viscosity (RVU) were read on the instrument
while breakdown and setback viscosities (RVU) were calculated.
Formulations for serendipity berry extract sweetened-bread
Six different samples (SSB0, SSB2, SSB3, SSB4, SSB5 and SSB6) of bread were
produced from various recipe formulations as shown in Table 1. Sample SSB0
served as the control while other samples were treated with serendipity berry
extract at different concentrations.
Table 1 Recipe for the production of Serendipity berry extract-sweetened breads
Treatment samples of the serendipity extractIngredients
sweetened breads
SSB0
SSB2 SSB3
SSB4
SSB5 SSB6
Wheat flour (g)
200
200
200
200
200
200
Edible salt (g)
2.5
2.5
2.5
2.5
2.5
2.5
Yeast (g)
2.5
2.5
2.5
2.5
2.5
2.5
Vegetable Fats (g)
5.0
5.0
5.0
5.0
5.0
5.0
5 % sugar
100
80
70
60
50
40
solution (ml)
Serendipity berry extract 0
20
30
40
50
60
(ml)
Distilled Water (ml)
30
30
30
30
30
30
Legend: SSB0 = 100 ml sugar solution, SSB2 = 80 ml sugar solution + 20 ml
serendipity berry extract, SSB3 = 70 ml sugar solution + 30 ml serendipity berry
extract, SSB4 = 60 ml sugar solution + 40 ml serendipity berry extract, SSB 5 = 50
ml sugar solution + 50 ml serendipity berry extract, SSB 6 = 40 ml sugar solution
+ 60 ml serendipity berry extract.
Figure 1 Flowchart for the production of serendipity berry extract-sweetened
bread
SSB6
SSB5
SSB4
SSB3
SSB2
SSB0
Preparation of serendipity berry extract-sweetened breads
The breads were prepared according to the AACC (2000) straight dough method
No 10-10B. The dougsh from each formulation was mixed for 5 min, raised for
30 min, punched for 4 min and raised for another 30 min. The dough was
divided, punched again for 5 min, rounded and moulded. Then it was placed in
Figure 2 Serendipity berry extract-sweetened breads.
Legend: SSB0 − 100 ml sugar solution treated-bread, SSB2 − 80 ml sugar
solution + 20 ml serendipity berry extract treated-bread, SSB3 − 70 ml sugar
solution + 30 ml serendipity berry extract treated-bread, SSB4 − 60 ml sugar
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solution + 40ml serendipity berry extract treated-bread, SSB5 − 50 ml sugar
solution + 50ml serendipity berry extract treated-bread, SSB6 − 40 ml sugar
solution + 60 ml serendipity berry extract treated-bread.
Sensory evaluation of the bread samples
A panel of 20 members who were regular consumers of white wheat bread was
selected among students and members of staff of the Department of Home
Economics and Food Science, University of Ilorin for the sensory analysis. The
panellists were instructed to evaluate the coded bread samples for acceptability of
colour, taste, after taste, aroma, crumb texture, crust colour and overall
acceptability using a nine point hedonic scale where 1 represented dislike
extremely and 9 represented like extremely. The panellists were also instructed to
rinse their mouths with drinking water after evaluating each sample.
Determination of total bacterial and fungal counts of the breads
The total viable bacterial and fungal (yeast and moulds) counts of the bread were
determined on days 0, 2 and 5, using the pour plate technique (Adegoke, 2004).
One gram of each bread sample was dissolved in 1 ml of 2 % sterile sodium
citrate solution in order to prepare a suspension. One millilitre of the suspension
was then used for the serial dilution of between 10 -1 and 10-3. At about 44 − 50
°C, 0.1 ml of the dilution was transferred from each dilution bottle into the
corresponding plates and about 15 ml of nutrient agar and potato dextrose agar
which were already prepared according to manufacturers' instructions for total
viable bacterial and fungal (yeast and moulds) counts, respectively were poured
and mixed thoroughly with the inoculums by rocking the plates. The plates were
incubated at 37 ºC for 24 hr and at room temperature (28±2 ºC) for 72 hr for
nutrient agar and potato dextrose agar, respectively. Bacterial and fungal colonies
were counted using a Stuart scientific colony counter and expressed as colony
forming units per gram (cfu/g) of samples.
Shelf life of the bread samples
The bread samples were stored under ambient temperature (28±2 °C) and
observed for 10 days. Visual observations for mould growth were carried out on
the samples throughout the storage period as stated by Ijah et al. (2014).
Statistical analysis
Data obtained for the pasting properties of the mixed dough, proximate
composition and sensory evaluation of the breads were subjected to one-way
analysis of variance (ANOVA) using statistical package for social sciences
(SPSS v.16.0) and means were separated using Duncan Multiple Range Test
(p˂0.05).
RESULTS AND DISCUSSION
Pasting properties of serendipity berry extract-treated wheat flour
The appearance, texture, digestibility and application of starch-based food
materials depend largely on their pasting properties (Onweluzo and Nnamuchi,
2009; Ajanaku et al., 2012). The pasting properties of the serendipity berry
extract-treated and the control flours are presented in Table 2. The peak viscosity
of the flours ranged from 110.7−195.4 RVU for SSB 2F and SSB5F respectively.
The peak viscosity of the serendipity berry extract treated flours increased with
increase in the concentration of the extract up to 50 % substitution level. SSB 2F
had a significantly (p˂0.05) lower peak viscosity value compared to SSB 0F
(control) while 30−60 % partial substitution of sugar with serendipity berry
extract resulted into significant (p˂0.05) increment in the peak viscosity of the
wheat flour. Peak viscosity is the measure of the swelling capacity of starchbased foods soon after heating prior to physical breakdown (Sanni et al., 2006).
Starch, starch components such as amylose and amylopectin, and degree of starch
damage are some of the factors that could influence the pasting viscosity of flour.
Trough viscosity is the minimum viscosity value in the constant temperature
phase of RVA which indicates the ability of paste to withstand breakdown during
cooling (Ekunseitan et al., 2016). Sample SSB0F had the lowest trough viscosity
(79.20 RVU) while SSB5F had the highest (179.4 RVU). Partial substitution of
sugar with serendipity berry extract generally increased the trough viscosity of
the flour, though the increments were not proportionate with the concentrations
of the serendipity berry extract. This result showed the ability of SSB0F paste to
withstand breakdown during cooling compared to the pastes of the serendipity
berry extract-treated samples.
The breakdown viscosity of the flours ranged between 16.85 RVU for SSB 5F and
39.90 RVU for SSB6F. No significant difference existed between SSB4 F and
SSB0F (control). It was observed that 20, 30 and 50 % partial substitution of
sugar with serendipity berry extract significantly (p˂0.05) decreased the
breakdown viscosity of the flour while significant (p˂0.05) increase in
breakdown viscosity was recorded with 60 % serendipity berry extract
substitution. Lower breakdown viscosity is an indication of higher heat and shear
stress stability during cooking (Adebowale et al., 2005). Final viscosity
indicates the ability of a starch-based food material to form paste after cooling
(26). The final viscosity of the flours ranged from 153.85 RVU for SSB 0F
(control) to 274.7 RVU for SSB6F. The final viscosity of the treated flours
increased with increase in the concentration of serendipity berry extract and they
were significantly (p˂0.05) higher than that of the control (SSB 0F). This implied
that the treated flour pastes were less stable after cooling. The lowest (73.35
RVU) and the highest (158.45 RVU) setback viscosities were recorded for SSB 0F
and SSB6F respectively. Significant (p˂0.05) differences existed among the
setback viscosities of the flours with the serendipity berry extract-treated flours
having higher values than the control (SSB 0F). Higher setback values are
synonymous to reduced dough digestibility (Shittu et al., 2001), while lower
setback during cooling of the paste indicates lower tendency for retrogradation
(Sanni et al., 2001).
Peak time indicates the time required for cooking to be achieved (Adebowale
et al., 2005). The peak time recorded for the flours varied between 5.62 min
(SSB2F) and 6.82 min (SSB0F). Partial substitution (20−60 %) of sugar with
serendipity berry extract resulted into decrease in the peak time of the flour,
although the peak time obtained for SSB3F and SSB5F were comparable with that
of the control (SSB0F). Hence, partial substitution (20-60 %) of sugar with
serendipity berry extract reduced the time required to cook wheat flour paste.
Pasting temperature is the minimum cooking temperature at which there is first
observable increase in viscosity due to the swelling of starch granules (Ikegwu et
al., 2009; Ekunseitan et al., 2016). The pasting temperature of the flour samples
ranged from 89.72 ºC for SSB0F to 95.82 ºC for SSB6F. Partial substitution (2060 %) with serendipity berry extract significantly increased the pasting
temperature of the flour. The highest pasting temperatures were recorded for the
flours at 10 and 60 % serendipity berry extract substitution levels. Higher pasting
temperatures obtained for the treated flour samples are indication of higher
energy cost, low components stability, higher gelatinization tendency and low
swelling properties of the starch granules.
Table 2 Effect of serendipity berry extract on the pasting properties of wheat flour
Sample
Peak
viscosity Trough
Breakdown
Final viscosity
(RVU)
viscosity (RVU) viscosity (RVU)
(RVU)
Setback
viscosity (RVU)
Peak time (min)
Pasting
(ºC)
temperature
SSB0F
114.5d± 0.56
79.20e±0.71
36.90b± 0.71
153.85e±0.92
73.35f±0.21
6.82a±0.35
89.72d±0.59
e
e
c
d
c
d
SSB2F
110.7 ±0.35
82.00 ±2.12
31.90 ± 0.71
195.4 ± 1.06
113.2 ±0.57
5.62 ±5.62
95.70ab±0.63
SSB3F
156.4b±0.14
134.0b±2.12
23.50d± 0.71
237.4c±0.71
105.4d±1.34
6.48ab±0.22
94.92abc±0.46
SSB4F
166.3b±0.29
129.3c±1.27
36.80b±0.28
252.8b±0.78
124.2b±0.42
6.18bc±0.71
94.18bc±0.74
a
a
e
a
e
ab
SSB5F
195.4 ±0.14
179.4 ±0.35
16.85 ±0.92
273.3 ±0.92
93.05 ±1.06
6.50 ±0.49
94.06c±0.57
SSB6F
155.5c±0.28
116.5d±0.01
39.9a±0.71
274.7a±1.41
158.45a±1.63
5.98c±0.78
95.82a±0.74
Values are means of triplicate determinations ± standard deviation. Means with different superscript in each column are signi ficantly different (P< 0.05). SSB0F = 100
ml sugar solution treated-flour, SSB2F = 80 ml sugar solution + 20 ml serendipity berry extract treated-flour, SSB3F = 70 ml sugar solution + 30 ml serendipity berry
extract treated-flour, SSB4F = 60 ml sugar solution + 40ml serendipity berry extract treated-flour, SSB5F = 50 ml sugar solution + 50ml serendipity berry extract
treated-flour, SSB6F = 40 ml sugar solution + 60 ml serendipity berry extract treated-flour.
Proximate composition and energy values of freshly baked serendipity berry
extract-treated bread
Table 3 shows the proximate composition and energy values of the freshly baked
serendipity berry extract-treated breads. Moisture content of the breads ranged
from 11.93−15.22 % for SSB2 and SSB6 respectively. The values fell within the
acceptable moisture limit (15 %) for dry products (Ijah et al., 2014). Although
the moisture content of the treated bread samples generally increased with
increase in the concentration of the serendipity berry extract substitution, 20−40
% partial substitution of sugar with serendipity berry extract resulted into
production of breads with lower moisture contents compared to the control
(SSB0). The significantly highest moisture contents recorded for SSB 5 and SSB6
could be attributed to the liquid nature of the serendipity berry extract used as
sugar substitute. Olaoye and onilude (2008) have also reported increased in
moisture content with increase in the level of breadfruit substitution in wheatbreadfruit breads. Moisture content is an indicator keeping quality and high
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moisture could result into shorter shelf life of the breads. Ash is the inorganic
material remaining after oxidation of organic matter and it is an indication of the
total minerals (Wilson, 1987). The lowest (0.75 %) and the highest (3.06 %) ash
contents were found in SSB2 and SSB6 respectively. Ash content of the treated
bread samples generally increased with increase in the concentration of
serendipity berry extract. This increment could be an indication of the presence
of higher minerals in the serendipity berry extract. This is plausible because
similar trend has also been reported for wheat-breadfruit flour breads (Olaoye
and Onilude, 2008) and date palm fruit pulp treated-wheat cookies (Peter et al.,
2017). The ash contents of breads with 30−60 % serendipity berry extract
substitution were observed to be higher than 1.43 % recorded for the control.
This suggests that the inclusion of serendipity berry extract could boost the
mineral content of bread.
The protein content of the breads ranged between 11.67 % for SSB0 (control) and
14.13 % for SSB6. The values of 12.26−14.13 % obtained for the protein contents
of serendipity berry extract-treated breads were higher than 11.67 % recorded for
the control (SSB0). This may be due to the high protein content of the serendipity
berry extract which must have contributed to the protein content of the wheat
flour, thus increasing the protein level of the serendipity berry extract treatedbread samples. This is plausible since the sweetness of serendipity berry has been
attributed to a protein known as monellin (Wlodawer and Hodgson, 1975;
Inglett, 1976). The crude fat of the bread samples ranged from 4.29−9.06 % with
the serendipity berry extract-treated breads recording significantly (p˂0.05)
higher values than the control (SSB0). It was observed that the crude fat of the
treated-breads with the exception of SSB4, increased as the concentration of the
serendipity berry extract substitution increased. This is an indication of higher fat
content in the serendipity berry extract compared to wheat flour. This is similar to
the report of Peter et al. (2017) on date palm fruit pulp treated-wheat cookies.
High fat content could shorten the shelf life of baked foods such as bread
(Ihekoronye and Ngoddy, 1985).
The fibre content of the breads fell within 1.24−2.50 %, recorded for the control
(SSB0) and SSB6 respectively. The fibre content of the bread samples except
SSB5 increased with increase in concentration of the serendipity berry extract
substitution. Partial substitution (20-60 %) of sugar with serendipity berry extract
generally increased the fibre contents of the breads. Similar trend has been
reported by Olaoye and Onilude (2008) for wheat-breadfruit flour breads and
Peter et al. (2017) for date palm fruit pulp treated-whole wheat cookies Higher
fibre content is advantageous in the diets as it increases faecal output, reduces
faecal pH, diabetes, incidence of colon cancer, obesity, heart diseases and certain
degenerative diseases (Cummings et al., 1996). The results showed that the
carbohydrate content of the breads ranged between 55.01 % and 68.14 %. Partial
substitution (20−60 %) of sugar with serendipity berry extract resulted into the
production of breads with significantly (p˂0.05) lower carbohydrate contents.
This could be due to the lower sugar content of serendipity berry (Inglett, 1976;
Oselebe and Nwankiti, 2005; Abiodun et al., 2014). It was observed that the
carbohydrate content of the treated bread samples generally decreased as the
concentration of the substituted serendipity berry extract increased. Similar trends
have been reported for wheat-breadfruit flour breads (Olaoye and Onilude,
2008) and date palm pulp meal sweetened bread (Obiegbuna et al., 2013).
Energy values of the bread samples
The energy values of the bread samples ranged from 352.21−376.83 kCal/g for
SSB4 and SSB3 respectively (Table 3). Energy values of the breads significantly
(P˂0.05) increased at 20 % and 30 % serendipity berry extract substitution levels
but decreased significantly (P˂0.05) at 40 % and 50 % substitution levels
compared to the control (SSB0). Bhise and Kaur (2014) have also reported
reduction in the calorific values of wheat bread with the incorporation of polyols
as a sugar substitute. No significant difference existed between the energy values
of SSB6 and the control (SSB0).
Table 3 Proximate composition and energy values of freshly baked serendipity berry extract-treated breads
Sample
Moisture (%)
Ash (%)
Crude protein Crude
fat Crude fibre Carbohydrate
Energy
value
(%)
(%)
(%)
(kCal/g)
SSB0
13.50b±0.38
1.43de±0.42
11.67c±0.18
4.29d±0.37
1.24d±0.14
68.14a±1.06
357.85c±3.03
SSB2
11.93c±0.09
0.75e±0.35
12.26bc±0.19
5.73c±1.03
1.58cd±0.24
65.96b±0.77
364.45b±1.52
SSB3
12.12c±0.51
1.75cd±0.35
13.10b±0.10
7.87ab±0.17
1.98bc±0.21
63.40c±0.47
376.83a±1.02
b
bc
bc
b
ab
d
SSB4
13.25 ±0.31
2.26 ±0.37
12.44 ±0.16
7.37 ±0.53
2.12 ±0.17
59.03 ±0.74
352.21d±1.36
SSB5
15.12a±1.21
2.75ab±0.35
12.52bc±0.91
8.33ab±0.24
2.11ab±0.14
57.16d±0.98
353.69d±1.68
SSB6
15.22a±0.22
3.06a±0.08
14.13a±0.21
9.06a±0.17
2.50b±0.22
55.01e±0.91
358.10c±2.12
Values are means of triplicate determinations ± standard deviation. Means with different superscript in each column are significantly different (P<
0.05). SSB0 = 100 ml sugar solution treated-bread, SSB2 = 80 ml sugar solution + 20 ml serendipity berry extract treated-bread, SSB3 = 70 ml sugar
solution + 30 ml serendipity berry extract treated-bread, SSB4 = 60 ml sugar solution + 40ml serendipity berry extract treated-bread, SSB5 = 50 ml
sugar solution + 50ml serendipity berry extract treated-bread, SSB6 = 40 ml sugar solution + 60 ml serendipity berry extract treated-bread.
Effect of serendipity berry extract on the consumer acceptability of wheat
breads
Table 4 shows the mean sensory scores for the colour, taste, after taste, aroma,
crumb texture, crust and acceptability of the bread samples. No significant
differences existed between the mean scores obtained for the colour, aroma,
crumb texture, crust colour and acceptability of SSB6 and the control (SSB 0) but
they were significantly (p˂0.05) higher than the mean values recorded for other
bread samples. Also, comparably high mean scores of 8.23 and 8.73 were
recorded for the taste of SSB6 and the control (SSB0) respectively. The control
bread (SSB0) had the lowest mean score of 6.73 while SSB 6 recorded the highest
mean score of 8.53 for after taste. This indicated that the partial substitution (2060 %) of sugar with serendipity berry extract positively influenced the after taste
of wheat bread samples. The bread (SSB6) produced by partially substituting
sugar with 60 % serendipity berry extract possessed similar or better sensory
attributes (colour, taste, after taste, aroma, crumb texture, crust colour and
acceptability) compared to the control bread sample (SSB0).
Table 4 Mean acceptability scores of freshly baked serendipity berry extract treated-breads
Sample
Colour
Taste
After taste
Aroma
Crumb texture
Crust colour
Overall acceptability
SSB0
8.67a±0.56
8.73a±1.25
6.73bc±1.11
8.67a± 1.06
8.70a±1.34
8.80a± 1.13
8.70a±1.15
cd
c
b
d
d
d
SSB2
7.03 ±1.29
7.17 ±1.19
7.80 ±1.21
6.73 ±1.49
6.70 ±1.39
6.73 ±1.26
6.83d±1.16
d
c
b
d
cd
d
SSB3
6.77 ± 1.31
6.97 ±1.30
7.33 ±1.16
6.43 ±1.20
6.77 ±1.19
6.67 ± 1.27
6.73d±1.17
SSB4
7.27bcd± 0.79
7.23bc±0.89
7.87b±0.94
6.93cd±0.98
6.93cd±0.98
7.03cd±0.77
7.10cd±0.76
SSB5
7.43bcd±0.68
7.30bc±0.59
8.00a±0.91
7.37bc±0.93
7.33bc±0.84
7.40bc±0.81
7.43bc±0.77
a
ab
a
a
a
a
SSB6
8.20 ±0.93
8.23 ±0.63
8.53 ±1.03
8.13 ±1.07
8.00 ±0.79
8.03 ±0.81
8.37a±0.67
Values are means of twenty determinations ± standard deviation. Means with different superscript in each column are significantly different ( P<0.05). SSB0 = 100 ml
sugar solution treated-bread, SSB2 = 80 ml sugar solution + 20 ml serendipity berry extract treated-bread, SSB3 = 70 ml sugar solution + 30 ml serendipity berry extract
treated-bread, SSB4 = 60 ml sugar solution + 40 ml serendipity berry extract treated-bread, SSB5 = 50 ml sugar solution + 50 ml serendipity berry extract treated-bread,
SSB6 = 40 ml sugar solution + 60 ml serendipity berry extract treated-bread.
Microbial counts of serendipity berry extract-treated breads during storage
Microbial enumerations could be used as indication of food safety and spoilage.
The results showing the influence of serendipity berry extract on the bacterial and
fungal counts of white wheat breads during 5 days of storage are displayed in
Table 5. The bacterial (0.0–61×103 CFU/g) and fungal (2.0–76×103 CFU/g)
counts generally increased throughout the 5 days storage period. However, the
values were within the safe limits stated by Ihekoronye and Ngoddy (1985).
The highest bacterial and fungal counts were recorded for the control bread
sample before and during the storage period. In comparison with the control
(SSB0), the serendipity berry extract treated-breads recorded lower bacterial and
fungal counts which were observed to decrease with increase in the concentration
of serendipity berry extract substitution Similar trends have been reported for
tigernut milk treated with different spices (Kayode et al., 2017). The generally
lower bacterial and fungal counts of the serendipity berry extract treated-breads
before and during the storage period could be attributed to the preservative effect
of the serendipity berry extract. This is similar to the report of Dauda et al.
(2017) on watermelon juice where serendipity berry extract was observed to
function as a sweetener and preservative. Bacteria and fungi are the major
organisms responsible for the spoilage of bread and their contamination with
bread could be from the raw materials used and during processing, handling and
storage (Ijah et al., 2014). The antimicrobial activities of serendipity berry
extract observed in this study could probably be attributed to the synergetic
action of secondary metabolites in the fruit extract.
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J Microbiol Biotech Food Sci / Kayode et al. 2019 : 9 (1) 115-120
Shelf life of serendipity berry extract-treated breads
The breads produced lasted for 6–8 days prior to observable visible spoilage
(Table 5). Breads with 50 % and 60 % serendipity berry extract had the longest
storage period of 8 days before visible spoilage was noticed. This might be due to
the ability of the serendipity berry extract to inhibit microbial growth. The
spoilage observed was indicated by black, yellow, and green coloration on the
bread and this was suspected to be mould growth. Incorporation of polyols
(glycerol, sorbitol and mannitol) has been reported to extend the shelf life of
bread from 4 days to 10 days mainly through moisture retention and relatively
water activity stability potentials of the polyols, although packaging materials
and storage conditions were shown to be contributory factors to the observed
shelf life elongation (Bhise and Kaur, 2014). However, caution must be taken in
the use of visual observation in evaluating the shelf life of bread because
mycotoxins and off-flavours might have been produced even before fungal
outgrowth would be visible (Magan et al., 2003).
Table 5 Effect of serendipity berry extract on the microbial counts and shelf-life of white wheat breads during storage
Sample
Bacterial count
Fungal count
0 day
2 days
5 days
0 day
2 days
5 days
3
3
3
(× 10 cfu/g)
(× 10 cfu/g)
(× 10 cfu/g)
(× 103 cfu/g)
(×103 cfu/g)
(×103 cfu/g)
Storage days
prior
to
visible
spoilage
SSB0
7
22
61
9
28
76
6
SSB2
4
19
55
6
24
62
6
SSB3
2
13
50
4
17
57
6
SSB4
2
10
43
3
15
51
7
SSB5
1
7
36
3
13
45
8
SSB6
NG
8
24
2
9
31
8
Values are means of duplicate determinations. NG = No growth, SSB0 = 100 ml Sugar solution treated-bread, SSB2 = 80 ml Sugar solution + 20 ml
Serendipity berry extract treated-bread, SSB3 = 70 ml Sugar solution + 30 ml Serendipity berry extract treated-bread, SSB4 = 60 ml Sugar solution +
40 ml Serendipity berry extract treated-bread, SSB5 = 50 ml Sugar solution + 50 ml Serendipity berry extract treated-bread, SSB6 = 40 ml Sugar
solution + 60 ml Serendipity berry extract treated-bread.
.
CONCLUSION
The use of serendipity berry extract as sugar substitute could be applied not only
to improve nutritional and sensory qualities but also to inhibit microbial growth
and thus extend the shelf life of wheat flour bread. This study showed that
serendipity berry extract could be used as natural sweetener and as a preservative
in bread. The sensory study also indicated that highly acceptable bread could be
produced by substituting sugar (5 % sugar solution) with 60 % serendipity berry
extract. This study therefore recommends serendipity berry extract as a natural
sweetener and as a substitute for chemical preservatives in bread production and
similar food applications.
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