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Mouthwatering but erosive? a preliminary assessment of the acidity of a basic sauce used in many indian dishes Nandini Ghai FJ Trevor Burke Dental Update 2025 39:10, 707-709.
Authors
NandiniGhai
BDS
University of Birmingham, School of Dentistry, College of Medical and Dental Sciences, St Chad's Queensway, Birmingham B4 6NN, UK
The aim of this study was to assess whether some types of Indian cuisine may contain erosive components. Indian dishes were prepared by a previously published method and their pH measured using a pH probe. The results indicated: (i) that some components of Indian cooking, such as tomatoes and red chilli powder, had the potential to erode enamel; (ii) that the pH of some foods was reduced with increasing temperature; and (iii) that all the basic masalas made and tested had a pH of less than 4.5.
Within the limitations of the study, it may be concluded that the basic sauce/masala used in north Indian dishes may have erosive potential.
Clinical Relevance: This information could be considered useful when advising patients who eat Indian curries about causes of acid erosion of their teeth.
Article
Anecdotally, toothwear has been noted in older members of the Asian community in the UK, with patients in the 4th or 5th decade of their life presenting with tooth substance loss (TSL). In this respect, the UK Adult Dental Heath Survey (1998) assessed the prevalence of TSL, including attrition, erosion and abrasion. The survey reported that 66% of UK adults had some wear in their anterior teeth involving dentine. On average, TSL was more extensive in older age groups, namely 58% in subjects >65 years old and 49% in subjects 55–64 years old.1
A variety of physical and chemical insults contribute to non-carious TSL.2 These include erosion (or corrosion),3abrasion, attrition and abfraction (Table 1).2 Dental erosion is caused by the acidic dissolution of tooth tissue with no bacterial involvement.2 Research has suggested that erosion is the most common cause of non-carious TSL2 and that sources of acid can be intrinsic or extrinsic (Table 2).1
Terminology
Definiton
Aetiology
Erosion
‘Tooth tissue loss produced by chemical or electrolytic processes of non-bacterial origin’2
*This acid is typically 100 times stronger than extrinsic erosion, and therefore more destructive.4,5
The UK National Dietand Nutrition Survey of Adults provided evidence for an increasing prevalence of toothwear, with the youngest age group (19–24) consuming more soft drinks than fruit and the oldest age group (50–64) consuming more fruit.1 Both soft drinks and fruit which contains citric acid have been identified as risk factors for erosion.6 However, older age groups may have more TSL because they have been exposed to the risk factors for longer, not because they consume larger amounts of fruit on a day-to-day basis.
Anecdotal evidence from experienced clinicians suggests that the diets of older Asian patients do not contain many of the typical dietary erosion factors (as suggested by Watson and Burke in 2000).5 However, it has been considered that green chillies have a pH which is sufficiently low to lead to erosion of the human dentition.7 These are a key ingredient of Indian cuisine. In this regard, northern Indian cuisine primarily consists of onion, tomatoes, cumin, turmeric, garlic, ginger cooked in pure cow ghee. Dairy products are heavily used in northern Indian cuisine in the form of yoghurt, lassi, paneer, makhan (white butter) and ghee. Southern Indian cuisine uses ingredients such as mustard seeds, onion seeds, nutmeg and coconut.8,9 Tomatoes form the basis of most Indian sauces, with vegetables being used commonly. It has previously been suggested that tomatoes and vegetables such as aubergines are acidic.10,11,12 There is also evidence to suggest that vegetarians are more at risk of developing TSL and, although there is some variation, Indians are predominantly vegetarians.10,11,12
The erosive potential of food can be assessed by testing the pH and by measuring the titratable acidity of a solution. Low pH is indicative of an acidic substance, whereas alkaline substances have a high pH. The normal pH of the mouth is neutral.13 Extrinsic acids, such as those in fruits and soft drinks, may lower the pH and dissolve the minerals in the enamel (calcium and phosphorus), causing demineralization. In this respect, enamel demineralization takes place below pH 5.5. This is known as the critical pH. A frequent decrease in pH below the critical pH may result in the progressive loss of enamel, ie toothwear or erosion.14
Materials and methods
Preparation of the masala
A standardized recipe of a basic north Indian sauce (masala) was used (Table 3) and scaled down by a factor of 4 to avoid food wastage. Each ingredient was weighed on a digital scale (accurate to 0.01 g) and prepared according to the recipe for 15 minutes. The masala was placed in a blender and liquidized for 1 min. 125 ml of distilled water at 60 °C was added and the masala liquidized for a further minute.
Ingredient
Quantity (g or ml)
Tomatoes
480
Onions
460
Ginger
50
Garlic
50
Green chillies
15
Dried fenugreek leaves
2.8
Cumin seeds
7.8
Red chilli powder
4.28
Salt
6.16
Garam masala powder
2.64
Coriander powder
2.4
Ground turmeric powder
2.12
Water
152
Oil
60
Initial study to assess the affect of temperature on pH
Once cooked, the masala was placed in a bowl and the pH measured, using a calibrated pH probe (Hanna Instruments Ltd, Leighton Buzzard, UK) capable of measuring pH from 1 to 14 +/- 0.01, at every 10 °C drop in temperature. This pH probe was used for each experiment and recalibrated for each experiment.
Preparation of individual ingredients
Each ingredient was weighed on a digital scale and prepared according to the recipe. Each ingredient was then liquidized for a minute followed by an additional minute of liquidation, once 125ml of distilled water at 60 °C was added. This did not apply to the powdered spices – they were added to 125ml distilled water and dissolved.
Determination of the titratable acidity of the masala as a whole and its individual constituents
The method described by Chadwick,15 to test the titratable acidity and erosive potential of ratatouille, was followed for the masala. The initial pH was measured of each sample using the calibrated pH meter. Each liquidized mixture was thoroughly stirred prior to titration. For each mixture, five 25 ml samples were measured out and titrated against 0.1 Molar sodium hydroxide whilst being stirred continually. The initial pH and pH changes were recorded using a pH probe. The volume of sodium hydroxide required to neutralize each sample was recorded and a mean calculated.
Results
The results of temperature vs pH are presented in Table 4. These indicated that the pH increased as the temperature was lowered. The results of chilli pH are presented in Tables 5 and 6, while the results of pH for different food ingredients are presented in Table 7. These indicate that, when tested individually, some ingredients were found to have a pH sufficient to erode enamel (ie below the critical pH of 4.5).
Temperature (ºC)
pH
82.7
4.3
72.5
4.3
62.3
4.4
52.7
4.6
42.7
4.7
32.5
4.8
Cooking Method
With Seeds
Mean pH
Mean volume of Sodium Hydroxide (ml)
Raw
6.9
0.11
Fried
6.1
0.27
Baked
6.8
0.1
Grilled
6.7
0.17
Poached
7.0
0.02
Cooking Method
Without Seeds
Mean pH
Mean volume of Sodium Hydroxide (ml)
Raw
7.0
0.07
Fried
6.3
0.24
Baked
7.2
0
Grilled
6.8
0.1
Poached
7.4
0
Individual Ingredients
Mean pH
Mean volume of Sodium Hydroxide (ml)
Onions
5.6
1.78
Garlic
6.9
0.08
Ginger
6.8
0.09
Whole green chillies (FRIED)
6.1
0.27
Tomatoes
4.6
5.97
Cloves
10.2
0
Black cardamom
5.1
1.35
Cumin
6.8
0.07
Salt
7.1
0
Red chilli powder
5
0.92
Turmeric
6.8
0.08
Garam masala
5.4
0.39
Coriander powder
6.3
0.17
Yoghurt
3.8
4.44
The results in respect of individual flavours (ie spices or yoghurt) are presented in Table 8. These indicated that the basic north Indian masala containing all the spices had a pH as low as 4.3. With no spices, the pH was 4.4. When the masala was cooked one spice at a time, the most acidic spices were chilli powder and black cardamom, producing masalas of pH 4.4. The least acidic were turmeric and coriander powder (pH 4.7). Although there was some variation, all the masalas had a pH lower than pH 5.5, therefore all could be considered to have the potential to erode enamel.
Spice/Ingredient
Mean pH
Mean volume of Sodium Hydroxide (ml)
Nil
4.4
8.45
Salt
4.5
7.09
Red chilli powder
4.4
8.31
Garam masala
4.5
7.88
Cloves
4.6
7.44
Black cardamom
4.4
8
Coriander powder
4.7
6.75
Turmeric
4.7
7.03
Yoghurt
4.2
9.42
All
4.3
8.64
The basic masala can be altered according to the dish being made. The results indicated that the most acidic variations contained yoghurt and ‘no onions’, as indicated by Table 9.
Type of Masala
Mean pH
Mean volume of Sodium Hydroxide (ml)
Cloves and Cardamom
4.4
7.65
Yoghurt
4.0
9.81
No onions
4.0
9.36
Yoghurt, cloves and Cardamom
4.1
9.2
Discussion
The aim of this study was to determine if the basic sauce used in Indian cuisine had any erosive potential, but this could not be fully assessed owing to a number of factors. First, this study focused only on the main sauce used in north Indian cooking and its variations. The erosive potential of the sauce with the addition of other ingredients, such as meat or other vegetables, was not measured. In addition, other elements of north Indian cuisine, such as marinades or accompaniments, were not tested.
When Tables 5 and 6 are examined, contrary to recent suggestions,7 the results of this study indicated that green chillies do not have a pH which is low enough to erode enamel. Frying chillies lowered the pH more than any other cooking method but the pH was still not low enough to erode enamel. Cooking the chillies whole tended to lower the pH, as opposed to cooking chillies without the seeds. Natural yoghurt was found to be acidic, but it may be considered less erosive because of its high concentration of calcium.
The ingredients and preparation of food varies from region to region in India,16 so these results may not reflect Indian cuisine as a whole. However, the ingredients described and used in the present study are used to varying degrees in many dishes prepared throughout India, and by the Indian community in the UK. Also, erosive potential is not only determined by the acidity of food but also by behavioural and biological factors. Medical conditions, such as acid reflux, have a significant role in dental erosion. Therefore, the extent of erosive effects may vary from person to person.
The initial experiment to assess the affect of temperature on pH suggested that temperature had an inverse relationship with pH: the higher the temperature the lower the pH. At 80°C the pH of the masala was 4.3. When left overnight for 15 hours in a chiller, the pH increased to 5.3. This is close to the critical pH and may therefore not be capable of causing erosion. In this regard, this may be considered to be not directly due to temperature but as a result of an equilibrium forming between hydrogen and hydroxide ions.17
It is evident from the results that the traditional masala is acidic. Even when the recipe was varied slightly, the masala was still acidic. However, the erosive potential may be considered to be less than drinks such as Coca Cola and orange juice.18 Recent studies suggest that even wine19 and herbal teas20 exhibit greater erosive potential, with their pH being as low as 3.
Indian cuisine often has a high fat content and it may be heavily spiced. Thus, the potential for the provocation of gastro-oesophageal reflux (GOR) must be considered. Results of a study of 12 subjects by Bartlett et al found that a curry meal taken with alcohol two hours before sleep provoked gastro-oesophageal reflux (GOR) in all participants of the study, but only to pathological levels in 50%.21 In this respect, GOR is commonly associated with dental erosion. Therefore, it may be the effect which the masala has on the stomach that indirectly causes dental erosion, rather than its acidic content.
Each masala consists of a variety of acids. It is very difficult to determine which acid is responsible for lowering the pH. When the individual components were tested, tomatoes had the lowest pH. Therefore it is possible that the tomatoes were responsible. This is supported by the results for the masala with no onions and the store-bought varieties.
Finally, the experimental methodology, similar to that utilized by Chadwick,15 was followed closely and may therefore be considered to provide accurate measurements. The results indicate the potential of certain types of Indian cooking to be erosive and may therefore be considered to contribute to TSL among those who eat it. However, further research is needed to elucidate the exact factors involved more fully.
Conclusion
Within the limitations of the present study, the results indicate that the basic sauce/masala used in north Indian dishes may have erosive potential. The addition of ingredients such as yoghurt may increase this. This information could be considered useful when advising Indian patients about acid erosion.
