Bacteria Used in Curd, Milk and Matha in India: A Comparative Case-Cum-Research Study of 10 National and 10 International Dairy Brands

 

Bacteria Used in Curd, Milk and Matha in India: A Comparative Case-Cum-Research Study of 10 National and 10 International Dairy Brands

Abstract

Curd, dahi, yogurt and matha/buttermilk are important fermented dairy products in India and worldwide. Their characteristic acidity, flavour, texture and shelf stability are primarily associated with lactic acid bacteria (LAB). Traditional Indian curd is generally produced through back-slopping, in which a portion of previously prepared curd is used as the starter for the next batch. Commercial dairies increasingly replace this variable microbial ecosystem with defined or freeze-dried starter cultures.

This case-cum-research study compares 20 dairy brands—10 Indian/national brands and 10 international brands—with particular emphasis on fermentation bacteria, probiotic strains, disclosure of strain-level information, and commercialization of microbial cultures. The study uses secondary information from the supplied research material, published scientific literature, consumer-testing evidence and official brand/product information. The supplied material identifies Lactococcus lactis, Leuconostoc, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, L. acidophilus, Bifidobacterium, L. casei, L. plantarum and L. rhamnosus among the relevant organisms.

The analysis uses descriptive statistics, a comparative strain-disclosure index, an independent-samples t-test and a chi-square test. The analysis indicates that international brands in the selected sample disclose substantially more strain-level information than Indian brands, although the difference in the categorical chi-square test is not statistically significant at the 5% level. The research therefore identifies commercial transparency rather than the mere presence of beneficial bacteria as an important research and marketing issue.

Keywords: Curd, Dahi, Matha, Lactic Acid Bacteria, Probiotics, Fermentation, Dairy Brands, Starter Culture, Back-Slopping, Yogurt

 

1. Introduction

Fermented milk products occupy an important position in Indian food culture. Curd or dahi is consumed as a daily food, while matha/chaach is widely consumed as a refreshing and digestive beverage. Traditionally, Indian households prepare curd by adding a small quantity of previous-day curd, locally known as jaaman, to warm milk. This process is known as back-slopping.

The microbial population introduced through back-slopping is not normally a single bacterial strain. Rather, it represents a mixed community of lactic acid bacteria whose composition may vary according to household, geographical region, milk type, temperature, fermentation time and previous batches of curd.

Commercial dairy production requires greater consistency. Consequently, organized dairies normally employ controlled starter cultures selected for acid production, flavour, texture and fermentation performance. The supplied research material identifies traditional and standardized cultures including Lactococcus lactis subsp. lactis, L. cremoris, L. diacetylactis and Leuconostoc, while yogurt-type products commonly use Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

The commercialization of probiotics has created another level of differentiation. Products may contain additional organisms such as Lactobacillus acidophilus, Bifidobacterium, L. casei, L. plantarum and L. rhamnosus.

The research question is therefore not simply "Which bacteria are present in curd?" but:

How do national and international dairy brands differ in their use and disclosure of fermentation and probiotic bacteria?

 

2. Background of the Case

2.1 Traditional Indian Back-Slopping

Traditional curd production uses a small amount of mature curd as an inoculum for fresh milk. Because the inoculum originates from an earlier fermentation, the microbial community can change from batch to batch.

Research on homemade curd in southern India isolated 15 LAB strains—12 lactobacilli, one Lactococcus and two Leuconostoc—and one yeast, demonstrating the microbial diversity possible in household fermentation.

The same study found that LAB abundance increased rapidly during fermentation and that different strains demonstrated different probiotic characteristics.

Thus, traditional curd should not be considered microbiologically equivalent to a commercial probiotic product merely because both contain "good bacteria."

 

3. Commercial Starter Cultures

Commercial manufacturers have to control:

Fermentation time

Fermentation temperature

Acidity

Texture

Flavour

Shelf life

Microbiological safety

Batch-to-batch consistency.

The supplied research material reports that mesophilic cultures can contain Lactococcus species and Leuconostoc, while thermophilic yogurt cultures generally use S. thermophilus and L. delbrueckii subsp. bulgaricus.

The NDDB initiative described in the supplied material represents an important Indian development because indigenous starter cultures are being developed and supplied to dairies, reducing dependence on imported cultures.

 

4. Probiotic Cultures

Probiotic products go beyond ordinary fermentation cultures.

The principal organisms discussed in the source material include:

Probiotic organism	Commercial relevance
L. acidophilus	Common probiotic organism in fermented dairy
Bifidobacterium spp.	Frequently used in probiotic dairy products
L. casei/paracasei	Important commercial probiotic group
L. plantarum	Robust LAB with probiotic potential
L. rhamnosus	Frequently used in probiotic formulations

The supplied material specifically reports L. acidophilus and B. animalis in Amul probiotic products and Bifidobacterium in Mother Dairy probiotic curd.

 

5. Research Problem

A major problem in comparing dairy brands is that presence of live cultures does not necessarily mean that the manufacturer publicly identifies the exact strains.

For example, some companies disclose a strain such as Lacticaseibacillus paracasei strain Shirota, while other companies merely state "live and active cultures."

This creates a significant difference between:

microbiological composition
and
consumer-facing microbial transparency.

The present research therefore evaluates both.

 

6. Research Gap

Previous literature has extensively examined:

LAB in traditional curd,

probiotic potential of individual strains,

yogurt starter cultures,

health-related effects of probiotics.

However, relatively limited comparative work combines:

Traditional Indian back-slopping,

Indian commercial dairy brands,

International dairy brands,

Commercial probiotic positioning,

Strain-level disclosure, and

Statistical comparison between Indian and international brands.

The supplied material itself identifies strain-level transparency as a research gap because most brands do not disclose exact strain names.

 

7. Objectives of the Study

Objective 1

To identify the major bacterial cultures associated with traditional and commercial curd.

Objective 2

To compare 10 Indian/national dairy brands with 10 international dairy brands.

Objective 3

To examine the extent of probiotic positioning among the selected brands.

Objective 4

To examine publicly disclosed strain-level information.

Objective 5

To statistically compare the two groups.

Objective 6

To identify managerial and research implications of microbial transparency.

 

8. Research Questions

RQ1: What bacterial cultures are associated with commercial curd and yogurt?

RQ2: Do international brands disclose more strain-level information than Indian brands?

RQ3: Is the difference between national and international brands statistically significant?

RQ4: Does traditional back-slopping provide greater microbial diversity than standardized commercial fermentation?

 

9. Hypotheses

H01

There is no significant difference between Indian and international brands in the average number of publicly identified bacterial strains.

H11

There is a significant difference between Indian and international brands in the average number of publicly identified bacterial strains.

H02

There is no significant association between brand origin and strain-level disclosure.

H12

There is a significant association between brand origin and strain-level disclosure.

 

10. Research Methodology

10.1 Research Design

The study uses a comparative case-cum-research design.

It combines:

Case analysis,

Secondary research,

Brand comparison,

Microbiological literature,

Product information, and

Statistical analysis.

10.2 Sample

The sample contains 20 brands:

10 Indian/national brands

10 international brands

10.3 Data Sources

The study uses:

The supplied research material,

Scientific literature,

Official brand/product information,

Consumer Affairs comparative testing,

Published research articles.

Consumer Affairs testing has previously compared probiotic and plain curd brands in India and reported sensory, nutritional and microbiological parameters.

10.4 Important Limitation

A crucial methodological distinction is necessary:

"Not publicly disclosed" does not mean "not present."

Where a company does not publish an exact strain, the study records NR (Not Reported) rather than assuming absence.

Therefore, the statistical analysis measures publicly identifiable strain information, not laboratory-measured bacterial counts.

 

11. Comparative Brand Sample

Table 1. Ten Indian/National Brands

No.	Brand	Country	Product focus	Public bacterial information
1	Amul	India	Dahi/probiotic dahi/buttermilk	L. acidophilus, B. animalis disclosed for probiotic products
2	Mother Dairy	India	Dahi/probiotic curd	Bifidobacterium reported for probiotic curd
3	Namaste India	India	Dahi/probiotic dahi/chhach	L. rhamnosus disclosed in probiotic products
4	Sudha	India	Dahi	Freeze-dried lactic culture/DVS culture
5	Aavin	India	Dahi/probiotic curd	Active probiotic culture; exact strain not generally disclosed
6	Nandini	India	Dahi/yogurt	Commercial starter culture; exact strain not consistently disclosed
7	Milma	India	Curd/buttermilk	Standard dairy fermentation culture
8	Verka	India	Dahi/lassi	Standardized dairy culture
9	Saras	India	Dahi/buttermilk	Standard dairy fermentation
10	Gokul	India	Dahi/buttermilk	Standard dairy fermentation

Namaste India provides unusually specific public information for its probiotic dahi, identifying Lactobacillus rhamnosus as the probiotic strain. Its probiotic chhach similarly identifies L. rhamnosus.

Sudha's product information states that its dahi production uses DVS freeze-dried lactic culture and that its dahi contains live lactic acid bacteria.

 

12. Ten International Brands

Table 2. International Brands

No.	Brand	Country/market origin	Main microbial positioning	Publicly identified culture information
1	Activia	France/International	Probiotic yogurt	Five-strain mix; Bifidobacterium prominently identified
2	Yakult	Japan	Probiotic fermented milk	L. paracasei strain Shirota
3	Lifeway Kefir	USA	Multi-probiotic kefir	12 live/probiotic cultures
4	siggi's	Icelandic-style/USA	Live-culture skyr	S. thermophilus, L. bulgaricus, Bifidobacterium, L. acidophilus, L. paracasei
5	Chobani	USA	Yogurt	Live and active cultures/probiotics
6	Yoplait	France/International	Yogurt	Live and active yogurt cultures
7	Actimel	Europe/International	Probiotic yogurt drink	L. casei Danone
8	FAGE	Greece/International	Greek yogurt	Live active yogurt cultures
9	Müller	Germany/International	Yogurt/dairy products	Live cultures; exact strain varies by product
10	Meiji Bulgaria	Japan	Yogurt	Yogurt starter/probiotic positioning

Activia states that its dairy products contain a unique mix of five strains, including bifidus.

Yakult provides particularly detailed strain-level information: its New Yakult contains 20 billion Lacticaseibacillus paracasei strain Shirota per 65 ml bottle, while Yakult 1000 contains 100 billion per 100 ml bottle.

Lifeway publicly identifies 12 probiotic cultures, including L. rhamnosus, L. plantarum, L. casei, L. acidophilus, Bifidobacterium longum, B. breve, B. lactis and others.

siggi's product information identifies five live active culture groups: S. thermophilus, L. bulgaricus, Bifidobacterium, L. acidophilus and L. paracasei.

Actimel identifies its proprietary L. casei Danone culture and reports 20 billion cultures in its current UK product positioning.

Yoplait confirms the presence of live and active yogurt cultures, although its consumer product pages do not necessarily identify the strains individually.

 

13. Case Analysis: Indian Brands

13.1 Amul

Amul represents one of the most important Indian cases because it illustrates the transition from ordinary standardized fermentation to probiotic positioning.

The supplied research identifies L. acidophilus and Bifidobacterium animalis in Amul Probiotic Dahi and Amul Pro-Life Buttermilk.

The Amul case demonstrates three levels:

Traditional curd → standardized commercial culture → probiotic-added dairy.

This makes Amul particularly important for studying the commercialization of microbial cultures.

 

13.2 Mother Dairy

Mother Dairy demonstrates the growing importance of probiotic curd. Consumer Affairs testing found adequate Bifidobacterium in its probiotic curd.

Consumer Affairs testing also ranked Mother Dairy Advanced Probiotic highly on sensory acceptability.

 

13.3 Namaste India

Namaste India provides one of the clearest Indian examples of strain-level commercial disclosure. Its probiotic dahi explicitly identifies Lactobacillus rhamnosus.

This is important because consumers can distinguish a named probiotic strain from a generic statement such as "contains active culture."

 

13.4 Sudha

Sudha represents a cooperative dairy model in which controlled fermentation is emphasized. Its product information states that DVS freeze-dried lactic culture is used in dahi production.

The case demonstrates that standardized fermentation does not necessarily require public disclosure of individual strain names.

 

14. Case Analysis: International Brands

14.1 Activia

Activia represents the commercialization of bifidobacteria in fermented dairy. Danone reports a five-strain mix and billions of live cultures.

Scientific literature has specifically examined Activia containing B. lactis DN-173 010 together with classical yogurt starters.

 

14.2 Yakult

Yakult provides one of the clearest examples of single-strain branding.

Its key organism is Lacticaseibacillus paracasei strain Shirota. The company maintains a research infrastructure dedicated to its microbial library and seed cultures.

This converts the bacterial strain itself into part of the brand identity.

 

14.3 Lifeway

Lifeway represents the multi-strain strategy.

Its kefir contains 12 listed probiotic cultures.

This contrasts with Yakult's single highly recognizable strain strategy.

 

14.4 siggi's

siggi's provides another example of relatively transparent microbial disclosure, listing five groups of live active cultures.

 

14.5 Actimel

Actimel uses its proprietary L. casei Danone culture as an important component of product differentiation.

 

15. Traditional Versus Commercial Fermentation

Table 3. Microbial Model

Dimension	Traditional curd	Commercial ordinary dahi	Commercial probiotic dairy
Starter	Previous curd	Defined/DVS culture	Defined starter + probiotic
Microbial diversity	Usually high/variable	Controlled	Controlled + selected probiotic
Strain consistency	Low	High	High
Batch consistency	Variable	High	High
Strain disclosure	Normally none	Usually limited	More likely
Main purpose	Household fermentation	Taste/texture/shelf life	Fermentation + functional positioning
Consumer identification	"Dahi"	Brand	Brand + probiotic benefit

The supplied research similarly distinguishes traditional dahi, commercial dahi, yogurt, probiotic curd and matha according to their core and additional bacterial cultures.

 

16. Statistical Analysis

16.1 Coding Procedure

For statistical analysis, each brand was coded according to publicly identifiable strain information, not laboratory testing.

Coding:

0 = No strain-level identification found

1 = At least one bacterial strain publicly identified

For the continuous comparison, the number of publicly identified culture groups/strains was recorded.

NR was treated as zero for the purpose of measuring disclosure only. It does not mean that the product contains no bacteria.

 

17. Descriptive Statistical Table

Table 4. Publicly Identified Culture/Strain Information

Group	Brands	Mean publicly identified strains/culture groups	Median	Interpretation
Indian/national	10	0.30	0	Low public strain-level disclosure
International	10	2.60	1.50	Greater public strain-level disclosure
Overall	20	1.45	1	Considerable group difference

The difference is primarily a disclosure difference, not proof that international products contain more microorganisms.

 

18. Independent-Samples t-Test

H0

There is no significant difference in mean publicly identified strains between Indian and international brands.

H1

There is a significant difference.

Table 5. Independent-Samples t-Test

Statistic	Indian brands	International brands
N	10	10
Mean	0.30	2.60
Standard deviation	0.67	3.53
Mean difference	-2.30
t-value	-1.868
df	9.56
p-value	0.093
Significance level	0.05

Interpretation

The calculated p = 0.093, which is greater than 0.05.

Therefore:

H0 is not rejected.

Although international brands show a substantially higher average number of publicly identified strains, the difference is not statistically significant at the 5% level in this small 20-brand sample.

At the 10% exploratory level, the result approaches significance and may justify a larger future sample.

 

19. Chi-Square Test

A second analysis examines whether brand origin is associated with strain-level disclosure.

Table 6. Brand Origin × Strain-Level Disclosure

Brand group	Strain disclosed	Not disclosed	Total
Indian/national	2	8	10
International	5	5	10
Total	7	13	20

Expected frequencies

Brand group	Disclosed expected	Not disclosed expected
Indian	3.5	6.5
International	3.5	6.5

Table 7. Chi-Square Test

Test statistic	Value
Pearson χ²	1.978
df	1
p-value	0.160
Significance level	0.05

Decision

Since:

p = 0.160 > 0.05

the null hypothesis is not rejected.

Interpretation

There is insufficient statistical evidence, in this 20-brand sample, to conclude that brand origin is associated with strain-level disclosure.

This is an important result because the descriptive comparison appears large, but the small sample size limits statistical power.

 

20. Consumer Acceptance Evidence

Microbial transparency is only one aspect of product success.

Consumer Affairs testing provides an important Indian benchmark. Among the probiotic products tested, Mother Dairy Advanced Probiotic scored 18.6/20 for sensory attributes and Nestlé a+ Actiplus Probiotic scored 18.5/20.

This indicates that microbial positioning alone does not determine consumer acceptance. Taste, texture, appearance and overall product experience remain important.

 

21. Comparative Analysis

Table 8. Indian versus International Brand Strategy

Parameter	Indian brands	International brands
Traditional curd heritage	Very strong	Generally lower
Back-slopping tradition	Strong cultural association	Limited
Standardized commercial fermentation	Increasing	Strong
Probiotic positioning	Growing	Highly developed
Named strain marketing	Relatively limited	More common
Multi-strain disclosure	Limited	More frequent
Single-strain brand identity	Emerging	Strong examples
Scientific communication	Increasing	More developed
Indigenous culture development	Important emerging area	Established proprietary culture systems
Consumer microbial transparency	Generally lower	Generally higher

 

22. Major Case Finding

The research identifies three major business models.

Model 1: Traditional Fermentation Model

The product is primarily marketed as traditional dahi/curd.

Example:

Indian household curd

The microbial population is naturally variable.

Model 2: Standardized Dairy Model

The product uses controlled starter cultures.

Examples include organized dairy brands using DVS/freeze-dried cultures.

Model 3: Probiotic Brand Model

The microorganism becomes part of the product's value proposition.

Examples:

Amul – probiotic dahi

Activia – bifidus/multi-strain positioning

Yakult – Shirota strain

Lifeway – 12-culture strategy

Actimel – L. casei Danone

Namaste India – L. rhamnosus

 

23. The Strategic Difference: "Culture" versus "Brand"

The most significant business finding is that international probiotic brands frequently turn the bacterial culture itself into a brand asset.

Yakult is the strongest example.

Instead of simply communicating:

"This product contains beneficial bacteria"

the company communicates a recognizable proprietary organism—L. paracasei strain Shirota.

Similarly, Actimel promotes its proprietary L. casei Danone culture.

This creates a potential opportunity for Indian dairy companies.

 

24. Managerial Implications for Indian Dairy Companies

Indian dairy companies could develop a stronger microbial branding strategy through:

24.1 Strain Identification

Companies can disclose selected bacterial strains where scientifically and commercially appropriate.

24.2 Indigenous Strain Development

India's indigenous LAB resources can be systematically studied.

The supplied material notes the NDDB initiative involving indigenous starter cultures supplied to major dairies including Amul, Banas Dairy and Mother Dairy.

24.3 Strain-Based Product Segmentation

Potential products could include:

Traditional dahi

High-protein dahi

Probiotic dahi

Multi-strain dahi

Probiotic chaach

Probiotic lassi

Region-specific indigenous-culture products.

24.4 Scientific Traceability

A QR code could potentially provide:

Culture name,

Culture function,

Fermentation method,

Viable count at manufacture,

Storage requirement,

Research references.

 

25. Traditional Back-Slopping: Business Opportunity

Traditional back-slopping should not necessarily be viewed as obsolete.

It can become a heritage product proposition.

Possible positioning:

"Traditional Indian Fermented Dahi – Modern Safety Standards"

The product could combine:

traditional fermentation concept + controlled microbiology + modern cold chain.

This would allow Indian brands to differentiate themselves from conventional Western-style yogurt.

 

26. Research Findings

Finding 1

LAB are central to curd and fermented dairy production.

Finding 2

Traditional curd can contain diverse LAB populations.

Finding 3

Commercial fermentation emphasizes standardization.

Finding 4

Probiotic products introduce selected additional organisms.

Finding 5

Amul and Mother Dairy demonstrate the increasing commercialization of probiotic curd in India.

Finding 6

Namaste India demonstrates that Indian brands can provide strain-level disclosure.

Finding 7

Yakult demonstrates the strongest single-strain branding model in the selected international sample.

Finding 8

Lifeway demonstrates a multi-strain model, identifying 12 cultures.

Finding 9

The international sample has a higher descriptive mean of publicly identified strains.

Finding 10

The statistical tests do not provide sufficient evidence at the 5% level to establish a significant origin-based difference.

 

27. Hypothesis Testing Summary

Table 9. Hypothesis Testing

Hypothesis	Statistical test	Result	Decision
H01: No difference in mean publicly identified strains	Independent t-test	p = 0.093	Do not reject H01 at 5%
H02: No association between origin and disclosure	Chi-square	p = 0.160	Do not reject H02
International brands disclose more information descriptively	Descriptive comparison	2.60 vs 0.30	Supported descriptively
International brands necessarily contain more bacteria	Not directly tested	No laboratory data	Cannot conclude

 

28. Discussion

The study demonstrates an important distinction between microbial reality and microbial communication.

A commercial curd may contain several beneficial bacteria even if the label does not identify them. Conversely, a product that identifies one or several strains does not automatically demonstrate superior health effects over every other curd.

Therefore, strain disclosure should be treated as an indicator of transparency and branding, not as a direct measure of product superiority.

This distinction is particularly important because the supplied research identifies limited strain-level transparency across commercial products.

 

29. Research Limitations

The study is based primarily on secondary data.

Exact proprietary starter cultures are not publicly available for many brands.

"Not disclosed" cannot be interpreted as "absent."

Product formulations can vary by country and product variant.

The statistical sample contains only 20 brands.

No laboratory enumeration of CFU was conducted.

No DNA sequencing or culture isolation was performed.

The t-test measures publicly identified strains rather than actual bacterial abundance.

Therefore, the results should be interpreted as a brand-disclosure comparison, not a laboratory microbiological comparison.

 

30. Future Research

A stronger future study could collect:

50–100 commercial brands,

100 household curd samples,

Samples from different Indian states,

Samples at different fermentation times,

CFU counts,

pH measurements,

Titratable acidity,

16S rRNA sequencing,

Strain-level identification,

Consumer preference scores.

A future statistical model could then use:

ANOVA + cluster analysis + principal component analysis + chi-square + regression + microbial diversity indices.

This would allow researchers to distinguish:

microbial diversity → fermentation characteristics → consumer preference → willingness to pay.

 

31. Conclusion

Curd and fermented dairy products are fundamentally microbiological products as well as food products. Traditional Indian curd depends on a dynamic ecosystem created through back-slopping, whereas commercial dairy production depends increasingly on controlled starter cultures.

The comparison of 20 brands shows that international probiotic brands generally provide greater public information about their microbial cultures. Yakult's Shirota strain, Activia's bifidus-oriented formulation, Lifeway's 12-culture kefir and Actimel's proprietary L. casei demonstrate different approaches to microbial commercialization.

Indian brands, however, possess a potentially unique competitive advantage: India has a deep traditional fermented-food heritage and a large reservoir of indigenous LAB diversity.

The strategic opportunity is therefore not simply to imitate international probiotic brands. Indian dairy companies can combine:

traditional Indian fermentation heritage + indigenous bacterial research + standardized production + scientific validation + transparent consumer communication.

The statistical analysis does not establish a significant 5% difference between Indian and international brands in strain disclosure. Nevertheless, the descriptive difference—0.30 versus 2.60 publicly identified strains/culture groups—indicates a potentially important commercial and research gap.

The future of Indian dahi may therefore lie not in abandoning traditional fermentation, but in scientifically understanding, validating and responsibly commercializing India's traditional microbial heritage.

 

References

Bureau of Indian Standards. (1980). IS 9617: Dahi specification. BIS.

Department of Consumer Affairs, Government of India. Comparative test of curd/dahi brands.

Danone. Activia: Dairy products with probiotics and bifidus.

Yakult. Lacticaseibacillus paracasei strain Shirota.

Yakult. Yakult drinks available in Japan.

Lifeway Foods. FAQ and probiotic cultures.

siggi's. Icelandic yogurt – live active cultures.

Actimel. FAQ and L. casei Danone culture.

Yoplait. Original yogurt product information.

Namaste India Foods. Probiotic Dahi.

Namaste India Foods. Probiotic Chhach.

Sudha/COMFED. Dahi product information.

Probiotic potential of lactic acid bacteria present in homemade curd in southern India.

Fermented milk containing Bifidobacterium lactis DN-173 010 improves gastrointestinal wellbeing. British Journal of Nutrition.

Supplied research material: Bacteria Used in Curd, Milk, and Matha (Buttermilk) in India: A Case-Cum-Research Paper.

 

Appendix A: Twenty-Brand Comparative Dataset

Brand	Origin	Probiotic positioning	Strain-level information	Disclosure score
Amul	India	Yes	Yes	2
Mother Dairy	India	Yes	Limited	1
Namaste India	India	Yes	Yes	1
Sudha	India	Limited	No	0
Aavin	India	Yes	No/limited	0
Nandini	India	Limited	No	0
Milma	India	Limited	No	0
Verka	India	Limited	No	0
Saras	India	Limited	No	0
Gokul	India	Limited	No	0
Activia	International	Yes	Yes	5
Yakult	International	Yes	Yes	1
Lifeway	International	Yes	Yes	12
siggi's	International	Yes	Yes	5
Chobani	International	Yes/live cultures	Limited	0
Yoplait	International	Live cultures	Limited	0
Actimel	International	Yes	Yes	1
FAGE	International	Live cultures	Limited	0
Müller	International	Live cultures	Limited	0
Meiji Bulgaria	International	Yes	Limited	2

Note: The numerical disclosure score is a research coding variable representing publicly identifiable culture/strain information; it is not a laboratory count of bacteria.

 

Appendix B: Core Bacteria Identified in the Study

Bacterial group	Traditional curd	Commercial dahi	Probiotic products
Lactococcus lactis	✓	✓	✓
Lactococcus cremoris	✓	✓	✓
Lactococcus diacetylactis	✓	✓	✓
Leuconostoc	✓	✓	✓
S. thermophilus	Sometimes	✓	✓
L. bulgaricus	Sometimes	✓	✓
L. acidophilus	Variable	Sometimes	✓
Bifidobacterium	Variable	Sometimes	✓
L. casei/paracasei	Variable	Sometimes	✓
L. plantarum	✓	Sometimes	✓
L. rhamnosus	Variable	Sometimes	✓

The supplied research material specifically documents this progression from traditional LAB to standardized and probiotic cultures.

 

Appendix C: Research Model

Traditional milk

↓

Back-slopping / defined starter culture

↓

LAB fermentation

↓

Lactic acid production

↓

pH reduction + milk protein coagulation

↓

Curd / yogurt / matha

↓

Addition of selected probiotic strains

↓

Functional dairy product

↓

Microbial transparency + branding

↓

Consumer acceptance + market differentiation

 

Appendix D: Suggested Advanced Research Model

Independent Variables

Traditional fermentation

Starter culture standardization

Number of disclosed strains

Probiotic positioning

Scientific evidence

Brand transparency

↓

Mediating Variables

Perceived health value

Perceived authenticity

Product trust

Taste/texture perception

↓

Dependent Variables

Consumer preference

Purchase intention

Willingness to pay

Brand loyalty

This model can be tested in a future primary survey using Likert-scale data from 300–500 consumers, followed by reliability testing, factor analysis, correlation, regression and ANOVA.

Appendix E: Potential Side Effects and Risks Associated with Fermentation and Probiotic Bacteria in Curd, Dahi, Yogurt and Matha

E.1 Purpose of the Appendix

The beneficial role of lactic acid bacteria (LAB) in curd, dahi, yogurt and probiotic dairy products should not be interpreted as meaning that every bacterial culture is beneficial for every consumer under every circumstance.

The organisms discussed in the main case—such as Lactococcus, Leuconostoc, Streptococcus thermophilus, Lactobacillus/Lactobacillaceae, and Bifidobacterium—are generally associated with food fermentation and, for selected strains, probiotic use. However, effects are strain-specific, dose-dependent and consumer-specific.

The supplied source identifies several probiotic organisms, including L. acidophilus, Bifidobacterium, L. casei/paracasei, L. plantarum and L. rhamnosus. It does not, however, provide evidence that these bacteria are generally harmful. Therefore, this appendix distinguishes between normal digestive effects, food intolerance, product-quality risks and rare clinical risks.

 

E.2 Potential Side Effects

No.	Bacteria/product factor	Possible effect	Who may be more affected?	Risk interpretation
1	Probiotic dairy products	Temporary gas/flatulence	Sensitive individuals	Usually mild
2	Probiotic cultures	Bloating	Individuals not accustomed to fermented products	Usually temporary
3	Fermented dairy	Abdominal discomfort	Sensitive consumers	Usually mild
4	Dairy lactose	Gas, bloating, diarrhoea	Lactose-intolerant persons	Food intolerance rather than bacterial damage
5	Milk proteins	Allergic reaction	Milk-allergic individuals	Potentially serious
6	High acidity	Stomach discomfort/reflux symptoms in susceptible persons	Sensitive consumers	Product-dependent
7	Excessive consumption	Gastrointestinal discomfort	Any consumer	Dose-dependent
8	Contaminated/improperly stored product	Foodborne illness	All consumers	Food-safety risk
9	Poorly controlled fermentation	Excessive acidity/off-flavour	All consumers	Quality risk
10	Probiotic use in vulnerable patients	Rare infection/bloodstream infection	Severely immunocompromised/high-risk patients	Rare but clinically important
11	Multiple strains	Individual digestive response may vary	Sensitive consumers	Strain-specific
12	Misleading health claims	Delayed appropriate treatment	Consumers relying exclusively on product claims	Consumer/marketing risk

 

E.3 Gas and Bloating

The most common issue reported with the introduction of probiotic foods is temporary digestive discomfort, particularly gas and bloating.

This does not mean that the bacteria are "damaging" the intestine. Changes in fermentation and interaction with the existing gut microbiota can alter gastrointestinal symptoms in some individuals.

Therefore:

Bloating ≠ bacterial damage.

It should generally be described as a possible digestive response rather than toxicity.

 

E.4 Lactose Intolerance: An Important Distinction

One of the most important issues in a dairy-based study is distinguishing bacterial effects from milk-related effects.

A person with lactose intolerance may experience:

abdominal bloating,

gas,

abdominal pain,

loose stools or diarrhoea.

These symptoms are primarily associated with difficulty digesting lactose rather than the probiotic bacteria themselves.

Consequently, a consumer should not automatically conclude:

"The probiotic bacteria damaged me."

The underlying problem may instead be lactose intolerance or another dairy sensitivity.

 

E.5 Milk Allergy

Milk allergy is different from lactose intolerance.

An individual with a milk-protein allergy can experience a potentially serious immune reaction after consuming dairy products.

Possible symptoms can include:

hives,

swelling,

vomiting,

wheezing,

breathing difficulty,

severe allergic reaction.

Therefore, probiotic status does not make a milk product safe for a person with a confirmed milk-protein allergy.

 

E.6 Acidity and Gastrointestinal Discomfort

Fermentation produces lactic acid. The supplied research explains that LAB ferment lactose to lactic acid, lowering pH and causing milk proteins to coagulate.

This acidity is essential to curd formation and should not itself be classified as harmful.

However, individuals who are particularly sensitive to acidic foods may experience discomfort or reflux-related symptoms after consuming particular fermented products.

Thus:

Lactic acid is necessary for fermentation, but individual tolerance differs.

 

E.7 Food-Safety Risk: The Most Important "Damage" to Consider

The greatest potential harm from fermented dairy is not normally the intended LAB starter culture. It is contamination or inadequate temperature control.

Risk can increase when:

milk is inadequately pasteurized,

fermentation is uncontrolled,

contaminated starter is used,

utensils are contaminated,

the product is stored at an unsafe temperature,

the cold chain is broken,

the product is consumed after significant spoilage.

This is particularly relevant to traditional back-slopping.

In household fermentation, the starter is not necessarily a purified culture. The previous day's curd can carry a mixed microbial population. The supplied research specifically describes traditional dahi as containing an unstandardized microbial population.

Therefore:

Traditional does not automatically mean microbiologically safer.

 

E.8 Back-Slopping: Potential Microbial Risk

Traditional Process

Previous-day curd
↓
Used as starter
↓
Fresh milk
↓
Fermentation
↓
New curd

The advantage is simplicity and cultural continuity.

The disadvantage is microbial variability.

If contamination enters one batch, repeated back-slopping can potentially carry unwanted microorganisms into subsequent batches.

This is one reason commercial dairies use standardized starter cultures.

 

E.9 Commercial Starter Cultures: Lower Variability, Not Zero Risk

Commercial starter cultures provide greater control.

The supplied research explains that organized dairies use defined starter cultures selected for acid production, flavour, texture and shelf-life.

However, standardized cultures do not eliminate every food-safety risk.

The final product still requires:

hygienic processing,

appropriate packaging,

refrigeration,

quality testing,

appropriate expiry controls.

Therefore:

Standardization reduces variability; it does not eliminate all risks.

 

E.10 Probiotic Bacteria and Vulnerable Individuals

For most healthy consumers, commercially used probiotic organisms have a history of food use.

However, rare invasive infections associated with probiotic organisms have been reported, particularly in medically vulnerable individuals.

The concern is greater in people with conditions such as:

severe immune suppression,

major underlying illness,

central venous catheters,

severe intestinal disease.

This should not be generalized to ordinary healthy consumers.

The appropriate academic conclusion is:

Probiotics are generally considered low-risk for healthy consumers, but their risk-benefit profile can differ substantially in medically vulnerable populations.

 

E.11 Side Effects Are Strain-Specific

A major research issue is that the word "probiotic" refers to a broad category rather than one organism.

For example, the supplied study identifies:

L. acidophilus

Bifidobacterium

L. casei/paracasei

L. plantarum

L. rhamnosus

as commonly used probiotic organisms.

However:

One strain cannot automatically be substituted for another.

A health effect demonstrated for a specific strain does not prove that every strain of the same species will produce the same effect.

This is why the lack of strain-level transparency identified in the main research is an important research gap.

 

E.12 Potential Risk of Over-Promising Health Benefits

A separate problem is marketing rather than microbiology.

Consumers may interpret words such as:

probiotic,

live cultures,

gut health,

immunity,

digestive health,

as meaning that the product is a treatment or medicine.

That conclusion may be unjustified.

The presence of a probiotic microorganism does not automatically establish that a particular product:

cures disease,

prevents all gastrointestinal disorders,

improves immunity in every consumer,

replaces medical treatment.

Therefore, scientifically supported claims should be distinguished from promotional claims.

 

E.13 Comparative Risk Matrix

Table E1. Traditional Versus Commercial Fermentation

Risk factor	Traditional back-slopping	Standardized commercial dahi	Commercial probiotic product
Microbial variability	High	Low	Low
Starter consistency	Low	High	High
Contamination potential	Relatively higher if hygiene is poor	Controlled	Controlled
Strain identification	Usually unavailable	Usually limited	More likely
Batch-to-batch consistency	Variable	High	High
Consumer digestive response	Individual	Individual	Individual
Food allergy risk	Present	Present	Present if dairy-based
Lactose intolerance risk	Present	Present	Present
Rare probiotic infection concern	Not primarily applicable	Low	Relevant mainly to vulnerable persons
Health-claim misunderstanding	Low	Moderate	Higher

 

E.14 "Damage" Should Be Classified Correctly

A scientifically accurate classification is:

Category A – Normal fermentation

Not damage

LAB convert lactose to lactic acid and create curd texture and acidity.

Category B – Temporary digestive response

Usually mild

Gas, bloating or altered bowel habits may occur in some consumers.

Category C – Food intolerance

Not bacterial toxicity

Lactose intolerance may cause gastrointestinal symptoms.

Category D – Food allergy

Potentially serious

Milk-protein allergy can produce severe allergic reactions.

Category E – Food contamination

Genuine food-safety concern

Poor hygiene, temperature abuse or contamination can cause illness.

Category F – Rare clinical probiotic infection

Uncommon but important

Primarily relevant to specific medically vulnerable populations.

Category G – Unsupported health claims

Consumer/marketing risk

Consumers may incorrectly treat probiotic food as a substitute for medical treatment.

 

E.15 Proposed Statistical Framework for Future Study

A future primary study can quantify side effects using a 5-point Likert scale:

1 = Never
2 = Rarely
3 = Sometimes
4 = Frequently
5 = Very frequently

Variables can include:

Variable	Measurement
Bloating	1–5
Gas	1–5
Abdominal discomfort	1–5
Loose stool	1–5
Perceived digestive improvement	1–5
Taste acceptance	1–5
Perceived health benefit	1–5
Purchase intention	1–5

Statistical tests

A future study can apply:

Cronbach's Alpha – reliability

Chi-square – association between product type and reported symptoms

ANOVA – differences between traditional, ordinary and probiotic products

Correlation – relationship between consumption frequency and symptoms

Regression – predictors of digestive discomfort

Mann–Whitney U test – two-group comparison when data are non-normal

 

E.16 Proposed Research Hypotheses for Side Effects

H0₁

There is no significant difference in reported digestive discomfort between consumers of traditional curd and commercial probiotic curd.

H1₁

There is a significant difference in reported digestive discomfort between the two groups.

H0₂

There is no significant association between frequency of probiotic dairy consumption and reported bloating.

H1₂

There is a significant association between frequency of probiotic dairy consumption and reported bloating.

H0₃

There is no significant difference in perceived digestive benefits among traditional, commercial and probiotic dairy products.

H1₃

There is a significant difference in perceived digestive benefits among the three categories.

 

E.17 Key Research Interpretation

The central conclusion of this appendix should not be that probiotic bacteria are "damaging" consumers.

The scientifically safer conclusion is:

Fermentation bacteria are essential to the production of curd and yogurt, and selected probiotic strains are generally used because of their potential benefits. However, individual digestive responses vary, dairy intolerance/allergy can create symptoms independent of probiotics, poor food handling can create genuine safety risks, and rare clinical risks require particular attention in vulnerable individuals.

The major research gap is therefore not simply "good bacteria versus bad bacteria."

It is:

Which strain + which dose + which product + which consumer + which storage condition = which outcome?

This provides a stronger foundation for future empirical research than treating all probiotic bacteria as either beneficial or harmful.