Therapeutic properties of whey

Therapeutic properties of whey

163

THERAPEUTIC PROPERTIES OF WHEY USED AS FERMENTED DRINK

T. Kar*; A.K. Misra

Department of Dairy Bacteriology, Faculty of Dairy Technology, West Bengal University of Animal and

Fishery Sciences, Mohanpur, Nadia, West Bengal, India

Submitted: August 05, 1998; Returned to authors for corrections: September 29, 1998; Approved: June 16, 1999.

ABSTRACT

Bioconversion of whey for preparation of beverage was standardized by utilizing

yoghurt cultures. The product, wheyghurt drink, made with 4% yoghurt cultures

inoculated in deproteinized whey (4.8% lactose, 0.66% ash, 0.46% fat and 0.40%

protein adjusted to pH 6.4) and incubated at 42oC for 8h had all the technological

requisite and dietetic criteria required in the product. The factors affecting the

antibacterial activity of wheyghurt drink against Escherichia coli, Staphylococcus

aureus, Shigella dysenteriae and Bacillus cereus were determined. There was a

significant variation (P<0.05) in the antibacterial activity of wheyghurt drink with

different levels of inoculum (1,2,4, and 8%) and concentration of sugar at 37, 42 and

45oC. Incubation at 42oC with 4% culture in whey exhibited highest inhibitory activity.

The product stored up to 5 days under refrigeration was of acceptable organoleptic

quality and requisite amount of microbial population (108 cfu/ml) to be potentially

beneficial.

Key words: whey, yoghurt, antibacterial activity

* Corresponding author. Mailing address: Department of Dairy Bacteriology, Faculty of Dairy Technology, West Bengal University of

Animal and Fishery Sciences, Mohanpur, Nadia, 741252, West Bengal, India

INTRODUCTION

The bioconversion of whey is an interesting

process from the view point of human nutrition,

especially for therapeutic purposes, in regard to

economy, and with advantage for reducing

environment pollution. Ancient Greeks as well as

Hippocrates, in 460 B.C., prescribed cheese whey

for the assortment of human ailments. Use of

Lactobacillus delbrueckii subsp., bulgaricus and

Streptococcus thermophilus in the manufacturing of

yoghurt have been extensively studied throughout

the world. Regular intake of this product looks

effective both in prevention and treatment of various

illness in man viz. gastrointestinal disorders (14),

hypercholesterolemia (10), antitumoral (3, 14),

reduced protein allergencity, treatment of vaginal

discharge, a cure for osteoporosis etc. (10). Although

yoghurt bacteria can grow well in whey (5, 23, 27)

use of these organisms in the preparation of whey

drink is still limited.

The present communication includes a report on

the preparation of wheyghurt drink, a fermented

whey beverage prepared by using L. delbrueckii

subsp. bulgaricus W and S. thermophilus H as culture

organisms, assessment of its antibacterial activity as

well as its acceptability and survival of the culture

organisms in the gastrointestinal segments of

wheyghurt drink fed rats.

Revista de Microbiologia (1999) 30:163-169

ISSN 0001-3714

164

T. Kar and A.K. Misra

MATERIALS AND METHODS

Preparation of whey

Whey was prepared by heating pooled cow milk

to 82oC and 2% citric acid solution was added at the

rate of 2gm. Per kg of milk. Complete coagulation

was effected within one minute and the whey filtered

muslim cloth is popularly known as chhana whey in

India where the coagulum chhana is used as a base

material for traditional sweetmeats. Whey obtained

was adjusted to pH 5.5 using 10% NaHCO3 solution

and was heated at 100oC for 10 minute with 0.4%

CaCl2 and kept undisturbed overnight at room

temperature and filtered to obtain deproteinized whey

(20). The product was then polished aseptically

through washed diatomaceous earth built up as one

half inch cake on a No. 54 Whatman filter paper placed

in Buckner funnel (19). The average composition of

whey was 4.8% lactose, 0.60% ash, 0.46% fat and

0.4% protein.

Source and Maintenance of Cultures

Lactobacillus delbrueckii subsp. bulgaricus W

and Streptococcus thermophilus H along with the

test cultures of pathogenic organisms viz. Bacillus

cereus, Escherichia coli, Shigella dysenteriae and

Staphylococcus aureus were obtained from the

National Collection of Dairy Organisms, National

Dairy Research Institute, Karnal, India. Lactobacillus

delbrueckii subsp. bulgaricus W. and Streptococuss

thermophilus H were maintained in sterile

deproteinized whey peptone broth (8), with the

following composition: peptone, 1gm; sodium

chloride, 0.5gm and whey 100ml. pH of the media

was maintained at 7.0. This whey medium was

transferred to standard corning screw capped tubes

(15x125 mm) by filling upto neck and were sterilized

by steaming for 30 min on three consecutive days.

The stock cultures were activated by three successive

transfers at 48 h interval. The pathogenic cultures

were maintained on nutrient agar slants (oxoid) and

were activated by three successive transfers at 24 h

intervals in nutrient broth.

Preparation of Wheyghurt Drink

A Schematic diagram conceptualizing the process

employed for the production of wheyghurt drink

using L. delbrueckii subsp. bulgaricus W and S.

thermophilus H cultures for direct consumption is

showed in Fig. 1. The effect of some factors such as

i) size of inoculum, viz. 1, 2, 4 and 8%. ii) incubation

temperature viz. 37, 42 and 45oC iii) concentration

of sucrose viz. 0, 6, 8, 10, 12 and 16% and iv) storage

at refrigeration temperature (5oC) for 1, 2, 5, 10 and

15 days – on the antibacterial activity of the drink

were also examined.

Analysis

Wheyghurt drink was analyzed for titratable

acidity (6), volatile acidity (15), lactic acid (4) and b-

D-galactosidase activity (13). The antibacterial activity

of the product was estimated by the modified cup agar

assay technique (7). Culture filtrates (or cell free

extracts) were collected by centrifugation at 3000 rpm

for 15-20 min. These were passed through Seitz filter

separately. Wells of 5 mm diameter were made on

solidified nutrient agar (inoculated with the pathogenic

test organisms) in each plate, and 50 µl of the cellfree

extract introduced transferred to wells. The plates

were incubated without inverting at 37oC for 18-24 h

and the diameters of inhibition zones were statistically

evaluated by analysis of variance (29).

Samples of wheyghurt drink were subjected to

sensory evaluation by a panel of 7 judges 9-point

hedonic scale (2) and analysed statistically by 2-way

classification (29).

For survival of wheyghurt drink organisms in the

intestine of rats 10 weanling male albino rats ³ 21

and £ 28 days old were used. Each animal was fed

with 15 g of rat feed synthetic ration containing 20%

casein, 50% sucrose, 24% hydrogenated vegetable

oil, 2% cod liver oil, 4% USP salt mixture, one

multivitamin capsule (500 mg Pfizer) per kg. diet

and 20 ml wheyghurt drink as preliminary diet for 7

days immediately prior to lights being extinguished.

After 16 h, food cups and any remaining food were

removed from the cages, the rats fasting for 8 h before

being fed again. One the 8th and final day of the

experiment, the animals except for one which served

as a fasted control were provided with only 20 to 24

g of specific test meal (wheyghurt drink) and given

30 min to consume it. At intervals of 60, 120 and

180 min. after the meal animals were anesthetized

with ether, weighed and its abdomen opened and

contents of the stomach, duodenum, and jejunum

were sampled after injecting and mixing 1.0 c.c.

sterile saline (0.85% NaCl) into the clamped-off

segments and aspirating with a sterile 5 c.c. syringe

and a 22 gauge needle. Serial ten-fold dilutions of

the aspirated contents were then prepared with sterile

saline, and pour plated in duplicate on Elliker Agar

(12).

Therapeutic properties of whey

165

Figure 1. Schematic diagram for the manufacture of wheyghurt drink

166

T. Kar and A.K. Misra

RESULTS AND DISCUSSION

Characteristics of the Product

The procedure shown in Fig.1 was adopted for

the preparation of wheyghurt drink using 4% mixed

culture of L. delbrueckii subsp. bulgaricus W and S.

thermophilus H in the ratio of 1:1. The final product

had a titratable acedity of 0.78 – 0.82%, 2.0 to 2.4

ml. of volatile acidity, 204-207 µg/ml lactic acid, b-

D-galactosidase activity of 2.30 µmol of lactose

hydrolysed/gm/h., mild acidic flavour, antibacterial

activity against all the four test organisms viz. E.

coli, S. aureus, Shigella dysenteriae and B. cereus

(inhibitory zone 8 to 10 mm) and a viable count of

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