Whey is a nutritious byproduct from cheese, Chhana and Paneer
industry containing valuable nutrients like lactose, proteins, minerals and
vitamins etc., which have indispensable value as human food. Regulations for
preventing disposal of untreated whey and recognition of the value of whey components
accelerated in the late 20th century. It resulted in to unraveling the secrets
of whey proteins and other components and established a sound basis for their
nutritional and functional value (Smithers, 2008). Whey
constitutes 45-50% of total milk solids, 70% of milk sugar (lactose), 20% of
milk proteins and 70-90% of milk minerals and most importantly, almost all the
water soluble vitamins originally present in milk (Horton,
1995). In India, it is estimated that about 100 million kg of whey is annually
derived as a by product which may cause substantial loss of about 70,000 tones
of nutritious whey solids (Parekh, 2006). In addition,
it is adding Biological Oxygen Demand (BOD) load to effluent (approx 35,000
to 45,000 mg L-1). However, Rao and Salooza (1990)
reported several methods for efficient disposal of whey such as treatment of
whey prior to disposal in sewage or utilization/conversion of whey for several
whey based product or by products. Considerable work has been done throughout
the world to utilize whey for production of Whey Protein Concentrate (WPC),
whey powder, lactose, lactic acid, whey paste etc (Panesar
et al., 2007).
The conversion of whey into beverages through fermentation or without fermentation
is one of the most attractive avenues for the utilization of whey for human
consumption. Beverages based on fruit and milk products are currently receiving
considerable attention as their market potential is growing. Besides being delicious,
these beverages are highly nutritious. In terms of functionality, whey protein
enhances protein content of beverage while improving its quality. The production
of a beverage from whey butter cheese and acerola juice has been shown to have
good commercialization potential, uniting the benefits provided by the former
with those of latter, including the ingestion of essential amino acids and increasing
the vitamin C content, resulting in a product of differentiated nutritive value
(Cruz et al., 2009). Singh
et al. (1999) attempted to develop a soft beverage from paneer whey
and guava. Sikder et al. (2001) formulated different
blends of whey beverages by using various levels of mango pulp (8-12%) with
0.04% acidity. Whey-based mango herbal beverage prepared with 2% Mentha
extract has been found to exhibit highest overall acceptability on the day of
preparation as well as after 30 days of storage (Sirohi
et al., 2005). Selected characteristics of whey-fortified banana
beverages stored at 4, 20, 30 and 40°C were monitored at specific time intervals
over a 60-day storage period. The sensory characteristics of the whey-banana
beverage stored at 4°C were studied and the product was a sour, sweet, smooth
beverage, with distinctive banana flavor and minimum off-flavor (Ernest
et al., 2005).
After citrus, banana is the most important fruit in the world trade. Banana is known for its ability to provide instant energy. A large quantity of unmarketable surplus fruit is available in all the banana growing regions. Very few processed products are marketed, primarily due to difficulty in retaining the characteristics color, flavor and texture of banana during processing. Beverage prepared from banana juice and whey in combination with edible herbal medicinal plant extract of Mentha arvensis will not have only excellent nutritional properties but will also posses therapeutic, prophylactic, antibacterial and organoleptic properties. Herbal extract of Mentha arvensis has preventive and curative value. It is used to treat sour throat, gastric problems and other problems related to gastrointestinal tract. It also act as a good appetizer, acceptable to consumer and at the same time make the product more palatable.
It has been proposed in the past to utilize whey in the formulation of a nutritious beverage, but this has not been so practical because the results have not been satisfactory in view of its high acidity rate, resulting in its poor taste characteristics. Therefore, a significant objective of the present study is to develop a beverage that not only is whey based, but which also exhibits desirable taste characteristics. The Mentha extract not only modifies taste and flavor characteristics of the beverage, but it also acts as natural preservative, therefore, minimizing the need of chemical or artificial preservatives. The present study was conducted to utilize the whey for the formulation of a new product using banana and Mentha extract having nutritional and medicinal values.
MATERIALS AND METHODS
The study was carried out in year 2009. The raw materials such as double toned milk (Vita brand), banana, Mentha arvensis (green leaves) and sugar were purchased from the local market.
Preparation of Banana Juice
The ripe bananas were washed and peeled. The pulping was done by hand pulper
and pulp was preheated to 65°C for 30 min in a water bath (Roy
et al., 1991). The pulp was pressed through a muslin cloth to extract
the juice. The banana juice was kept at a refrigeration temperature (7±1°C)
Preparation of Milk Whey and Mentha Extract
The milk was heated in a stainless steel vessel to 84°C. The hot milk
was acidified by adding citric acid (2%) followed by continuous stirring resulting
in complete coagulation of milk protein (casein). The liquid (whey) was filtered
using muslin cloth. Mentha extract was prepared from fresh leaves. The
leaves were washed, ground in a mixer grinder and filtered using muslin cloth.
Preparation of WBBH Beverage
Whey Based Banana Herbal (WBBH) beverages were prepared with the addition
of Mentha extract following the method followed by Sirohi
et al. (2005). For the preparation of 100 mL of herbal beverage,
whey amount varying from 78 to 82 mL was added with 10 mL of banana juice and
0 to 4% of Mentha extract (Table 1). The whey, banana
juice and sugar were mixed in the given amount, preheated to 45°C before
mixing Mentha extract (Fig. 1). The beverages obtained
were filtered and filled into presterilized glass bottles (200 mL) and sealed.
Pasteurization of filled bottles was done in boiling water for 30 min (Lal
et al., 1998) and cooled to room temperature.
Bottles containing beverages were stored at refrigerated temperature (7±1°C)
for 20 days. Samples were drawn at intervals of 5 days and evaluated for physico-chemical
and organoleptic properties.
The milk, banana juice, whey and herbal beverage were analyzed for their
different physico-chemical properties. Total soluble solids were determined
with an sErma hand refractometer (0-32°C) and the values were expressed
||Recipe for the preparation of 100 mL of WBBH beverage
|P0 is control beverage
||Flow chart for preparation of WBBH beverage
Total acidity was calculated in terms of lactic acid for whey and citric acid
for banana juice and herbal beverage by titrating against 0.1N NaOH according
to AOAC (1995) method. The reducing and total sugars were
determined by the method as described by Ranganna (1986).
Protein content was determined by Kjeldahl method for nitrogen estimation, using
factor of 6.38 for conversion of nitrogen into protein (BIS,
1961). Fat content was determined by Gerber centrifuge method (BIS,
Sensory Analysis of Beverage
The sensory analysis was performed on a 9-point hedonic scale by a panel
of 10 semi trained members. The beverage samples prepared with the varying levels
of Mentha extract were subjected to sensory evaluation by a panel of
10 members. The beverage samples were evaluated for color, appearance, flavor,
taste and overall acceptability. The evaluation was done at an interval of 5days
during the storage period of 20 days.
Data obtained were subjected to statistical analysis to find out the effect
of different levels of Mentha extract and storage period on physico-chemical
and sensory characteristics of the product. The data were analyzed statistically
in a split plot Completely Randomized Design (CRD) with main plot as five levels
of Mentha extract with three replications. The storage period was considered
as split plot factor with five levels randomized with each main plot. The following
statistical model was followed:
Yijk = μ+Pi+Sj+(PxS)ij+Eijk
where, Yijk is Response of study variable due to effect of ith Mentha extract level (Pi) kept up to jh storage period (Sj ) factor in the kth replication (i= 0,1,2,3,4; j = 0,1,2,3,4; k = 1,2,3). μ is General mean. Eijk is Error associated with the variables due to the effect of Ith Mentha extract level (Pi) and jth storage period (Sj ) in the kth replication.
RESULTS AND DISCUSSION
Physico-Chemical Characteristics of Whey and Banana Juice
The banana juice and whey were analyzed for their physicochemical properties.
The use of water was substitute by whey in the beverage preparation. As shown
in Table 2, whey showed 7.37 °Brix TSS, 5.5 pH, 0.004%
fat, 0.32% acidity (measured as percent lactic acid) and 0.17% protein. The
banana juice showed 15.33 °Brix TSS, 4.9 pH, 0.43% acidity (measured as
percent citric acid) and 17.6% total sugar.
Effect of Mentha Extract Concentration and Storage Period on Physico-Chemical
and Sensory Characteristics of WBBH Beverage
The TSS content of freshly prepared beverage samples of P0 (control),
P1, P2, P3 and P4 was measured as
13.87, 14.3, 14.2, 14.0 and 14.1 °Brix, respectively (Table
3). It was observed that the concentration of Mentha extract did
not affect the TSS content of beverages appreciably. The value of TSS for different
concentration levels of Mentha extract were comparable and did not increase
or decrease with the increasing levels of extract. Beverage prepared with Mentha
extract and stored at 7±1°C was analyzed at 5 days interval.
Table 3 shows that the storage period had statistically significant
effect on the TSS of the beverages (p<0.05).
||Physico-chemical characteristics of banana juice and whey
|CA: Citric acid, LA: Lactic acid, SD: Standard deviation
||Effect of treatment (Mentha arvensis concentration)
and storage period on TSS (°Brix), acidity (%) and pH of WBBH beverage
The TSS of the beverages increased gradually with the advancement of storage
period in all the five concentration levels of Mentha extract. The highest
value of TSS was recorded to be 14.80 °Brix at the end of 20 days of storage
for the beverage containing 1% Mentha extract. The effect of Mentha
extract concentration on average TSS values of different beverages during
storage was also significant except between P3 and P4
levels. The interaction effect between Mentha extract concentration and
storage period was also significant (p<0.05). Barwal
et al. (2005) also observed an increase in the TSS of the developed
bitter gourd RTS drink during storage. However, the results of the present study
in regard to TSS are in contradiction with the results of study by Kumar
and Manimegalai (2005), who observed no change in the TSS of whey-based
papaya RTS beverage during a storage period of 90 days. The possible reason
for increase in TSS in the present study might be due to use of different fruit
crops as banana has higher starch content in comparison to papaya, which may
undergo hydrolysis in to monosaccharides and other soluble sugars during storage
period (Mayer, 1960).
Acidity of fresh beverages P0 (control), P1, P2,
P3 and P4 was 0.50, 0.38, 0.32, 0.35 and 0.36%, respectively
(Table 3). The effect of storage period on the acidity of
beverages was found to be significant and the mean value of 0.38% for acidity
in case of freshly prepared beverages increased to 0.49% in the samples stored
for 20 days. No significant increase in the acidity was observed when Mentha
extract concentration was increased from 2 to 3% and the mean values of
acidity during storage for P2 and P3 were similar. The
interaction effect of Mentha extract concentration and storage period
on acidity was significant (p<0.05). The increase in acidity with storage
period was recorded in all the treatments. The increase in acidity was due to
conversion of lactose to lactic acid and formation of organic acid by ascorbic
acid present in banana juice. This increase might also have been attributed
to polyphenols present in Mentha extract and their degradation. The conversion
of proteins into amino acids during storage is also possible. The results are
in agreement with the findings reported by Soliman et
al. (1995) and Sikder et al. (2001).
The pH values were also not affected due to variation in concentration levels
of Mentha extract. The pH value for freshly prepared beverage samples
of P0, P1, P2, P3 and P4
were 5.23, 5.5, 5.37, 5.6 and 5.67, respectively (Table 3).
As shown in Table 3, the storage period had a significant
decreasing effect on the pH of the beverages with a mean value of 5.47 for freshly
prepared beverages and 5.01 for beverages stored for 20 days. The Mentha
extract concentration also affected the pH of the beverages significantly
(p<0.05); however, a no definite increasing or decreasing trend was observed.
The interaction effect of Mentha extract concentration and storage period
on pH was also significant (p<0.05). With the increase in storage period,
the pH of all treatments decreased. This fact is in accordance with the results
obtained for acidities of different beverage samples as with increase in acidity
pH correspondingly decreases. This may be due to the production of organic acids
and amino acids due to the action of ascorbic acid on sugar and protein content
of the beverages. Lactose and proteins are converted into lactic acid and amino
acids leading to increase in acidity and decrease in pH of beverages. Similar
results have also been reported by Kalra et al. (1991)
and Sikder et al. (2001) for mango RTS.
The total sugar content of freshly prepared beverage samples of P0,
P1, P2, P3 and P4 were 17.12, 17.44,
17.36, 17.48 and 17.11, respectively (Table 4). The storage
period had no significant effect on the total sugar content of beverages and
the mean value of 17.30% for freshly prepared beverages remained almost same
after 20 days of storage (17.31%). The results are in agreement with those of
Sirohi et al. (2005), who also observed no variation
in the total sugars content during the storage of whey-based mango herbal beverage.
However, the results of the present study are in contradiction with those of
Barwal et al. (2005) and Kumar
and Manimegalai (2005), who observed a decrease in the total sugars content
during storage of RTS from bitter gourd and whey-based papaya RTS, respectively.
However, the storage period in these studies was much higher i.e., 180 and 90
days, respectively which could have favored the Maillard reaction and other
chemical reaction of sugars with acids during the storage resulting in decrease
in total sugar content. The effect of Mentha extract concentration was
significant on the total sugar content of the beverages (p<0.05).
||Effect of treatment (Mentha arvensis concentration)
and storage period on total sugars and reducing sugars content of WBBH beverage
The total sugar content of 17.15% in the control sample (P0) increased
to 17.48%, when Mentha extract concentration was increased to 3% (P3).
The interaction effect of Mentha extract concentration and storage
period on the total sugar content was non-significant.
The reducing sugar content of the beverages increased during storage period.
The increase in reducing sugars during storage might be due to hydrolysis or
inversion of non-reducing sugars to reducing sugars (Aruna
et al., 1997; Srivastava, 1998). Similar
observations have also been reported by Sethi (1992)
for lime-ginger cocktail and Krishnaveni et al. (2001)
for jackfruit beverages.
Effect of Mentha Extract Concentration and Storage Period on Sensory
Characteristics of WBBH Beverage
The storage period significantly decreased the color ratings of the beverage
(p<0.05) and the mean value of 7.70 for color for the freshly prepared beverage
decreased to 5.48 after 20 days of storage (Table 5). The
Mentha extract concentration had a significant effect on color at 4%
level (p<0.05) with 1% level of Mentha extract concentration showing
maximum liking for color in beverage. The interaction effect of the storage
period and Mentha extract concentration was non-significant. The appearance
of the beverages was affected significantly with storage and it decreased to
a value of 5.52 after 20 days from initial value of 7.38 (Table
5). The interaction effect of storage period and Mentha extract concentration
was non-significant on the appearance. The taste and flavor decreased significantly
with storage period and the mean values of 7.50 and 7.58 for flavor and taste,
respectively in the freshly prepared beverage decreased to 5.20 and 4.76 after
20 days of storage (Table 6). The decrease in the flavor score
during storage could be possibly due to loss of volatile aromatic substances
(Thakur and Barwal, 1998). The effect of Mentha extract
concentration on the flavor and taste was significant and at 4% level of concentration,
it decreased the flavor and taste significantly after a significant increase
in taste and flavor up to a level of 2% (p<0.05).
The overall acceptability of the beverage during 20 days storage period decreased significantly from 7.61 to 5.22 and the product was slightly desirable up to 15 days having a value of 6.00 for overall acceptability (Table 6). The increase in Mentha extract concentration increased overall acceptability significantly up to 2% level and after further increase in its concentration, overall acceptability decreased.
||Effect of treatment (Mentha arvensis concentration)
and storage period on color and appearance of WBBH beverage
||Effect of treatment (Mentha arvensis concentration)
and storage period on flavor, taste and overall acceptability of WBBH beverage
From the results of the present study, it can be concluded that a whey based banana herbal beverage can be prepared successfully with the incorporation of 2% Mentha extract. The beverage can be stored at refrigeration temperature without adding any chemical preservative with desirable consumer acceptability up to 15 days. The product can prove a nutritionally as well as organoleptically desirable beverage with agreeable taste, energy providing due to whey proteins and banana juice in it. Product developers seeking out wheys functional and nutritional attributes to tap the tremendous growth opportunities in the beverage industry can move forward for the development of such herbal beverages based upon whey and other fruits.