Quality of milk in Imphal : A preliminary survey
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Akoijam Meerabai and Dayanidhi Huidrom (Intellisome Food Testing and Research Centre)
Contd from previous issue
Sampling and data
Samples were collected from different spots within Imphal during the period of September, 2024. Every possible measure was adopted to ensure the integrity of sampling. All records are maintained. Sl. No. 4 and 5 are not brand names but their original source as told by retailers.
To detect detergent in milk, start by adding 7.5 ml of methanol to 2.5 ml of milk. Methanol is used to help dissolve potential detergent residues in the milk. After adding the methanol, thoroughly mix the samples and then filter to remove any solid particles. Take 2 ml of the filtered liquid for further testing.
Next, add 2 ml of methylene blue solution to the filtrate and shake vigorously. Methylene blue is a dye that binds to certain chemical compounds, making them easier to identify. Then, add 4 ml of chloroform to the solution and shake well again. Chloroform helps to extract the methylene blue-detergent complex into a distinct layer.
The presence of detergent in milk is indicated by the formation of a darker blue color. The deeper the blue shade, the higher the concentration of detergent in the sample. If no significant color change is observed, the milk sample is unlikely to be adulterated/ contaminated with detergent. This simple yet effective test offers a way to quickly determine the presence of harmful detergents, ensuring that the milk is safe for consumption.
Starch
To detect starch in milk, a specific chemical reaction involving iodine is required. This reaction interacts with starch molecules.
To carry out the test, 4 ml of each milk sample is placed in test tubes and heated in a boiling water bath until they reach boiling point. This ensures that any starch present will interact with the chemicals added later. After boiling, the samples are cooled under running tap water to bring them back to room temperature.
Once cooled, 10% acetic acid is added to each sample. Acetic acid helps to break down any complex molecules that may interfere with the test. Following this, 0.2 ml of iodine solution is added to the milk samples. Iodine reacts with starch, forming a blue or grey-colored compound. The results are visible almost immediately. If the milk sample turns yellow, it indicates the absence of starch, meaning the milk is pure. However, if the sample turns grey, it suggests the presence of starch, confirming adulteration.
This method is both simple and reliable, providing a quick way to assess whether milk has been tampered with. By using iodine’s interaction with starch, this test can help ensure that milk being consumed is free of additives that alter its nutritional properties.
Milk density
The density or specific gravity of milk is a crucial indicator of its quality. Pure milk has a specific density that can change if adulterants, such as water, are added. The density can be determined using a lactometer, a specialized device designed for this purpose. The lactometer reading provides insights into whether the milk has been diluted or contains additional substances.
To determine the milk's density, a 50 ml measuring cylinder is filled with the milk sample. A calibrated thermometer is inserted into the milk to measure its temperature, as the temperature can affect the lactometer reading.
Validation
All tests are validated to ensure the methods elicit the desired response. For example, detergent is inten- tionally added to the sample and checked for response.
The survey results indicate that starch and detergent, two common milk adulterants, were absent in any of the tested samples. This suggests that, at least for the tested samples, these harmful substances are not being used in Imphal region, ensuring a level of safety for consumers.
The absence of starch and detergent is a positive indicator of the general quality of milk, but vigilance is still necessary for other adulterants.
However, the milk density test revealed a varying degree of density across the different samples. Kongpal Dairy, with a density of 1.020g/ml, exhibited the lowest density, which is an indicator of possible highest water dilution. The other samples, though not as diluted as Kongpal Dairy, still showed variation in density, which may impact the nutritional quality of the milk.
The significant variation in milk density calls for more stringent monitoring of milk quality, as dilution practices can affect both nutritional values and consumer trust.
This preliminary survey lays the foundation for ongoing, broader studies and more robust milk safety regulations in the region, aimed at protecting public health.
Further studies should explore other possible adulterants and involve a larger sample size to comprehensively assess the milk quality across more diverse sources within Imphal. Establishing a regular surveillance program is essential to ensure consistent quality standards and to safeguard consumer health.
Contd from previous issue
Sampling and data
Samples were collected from different spots within Imphal during the period of September, 2024. Every possible measure was adopted to ensure the integrity of sampling. All records are maintained. Sl. No. 4 and 5 are not brand names but their original source as told by retailers.
To detect detergent in milk, start by adding 7.5 ml of methanol to 2.5 ml of milk. Methanol is used to help dissolve potential detergent residues in the milk. After adding the methanol, thoroughly mix the samples and then filter to remove any solid particles. Take 2 ml of the filtered liquid for further testing.
Next, add 2 ml of methylene blue solution to the filtrate and shake vigorously. Methylene blue is a dye that binds to certain chemical compounds, making them easier to identify. Then, add 4 ml of chloroform to the solution and shake well again. Chloroform helps to extract the methylene blue-detergent complex into a distinct layer.
The presence of detergent in milk is indicated by the formation of a darker blue color. The deeper the blue shade, the higher the concentration of detergent in the sample. If no significant color change is observed, the milk sample is unlikely to be adulterated/ contaminated with detergent. This simple yet effective test offers a way to quickly determine the presence of harmful detergents, ensuring that the milk is safe for consumption.
Starch
To detect starch in milk, a specific chemical reaction involving iodine is required. This reaction interacts with starch molecules.
To carry out the test, 4 ml of each milk sample is placed in test tubes and heated in a boiling water bath until they reach boiling point. This ensures that any starch present will interact with the chemicals added later. After boiling, the samples are cooled under running tap water to bring them back to room temperature.
Once cooled, 10% acetic acid is added to each sample. Acetic acid helps to break down any complex molecules that may interfere with the test. Following this, 0.2 ml of iodine solution is added to the milk samples. Iodine reacts with starch, forming a blue or grey-colored compound. The results are visible almost immediately. If the milk sample turns yellow, it indicates the absence of starch, meaning the milk is pure. However, if the sample turns grey, it suggests the presence of starch, confirming adulteration.
This method is both simple and reliable, providing a quick way to assess whether milk has been tampered with. By using iodine’s interaction with starch, this test can help ensure that milk being consumed is free of additives that alter its nutritional properties.
Milk density
The density or specific gravity of milk is a crucial indicator of its quality. Pure milk has a specific density that can change if adulterants, such as water, are added. The density can be determined using a lactometer, a specialized device designed for this purpose. The lactometer reading provides insights into whether the milk has been diluted or contains additional substances.
To determine the milk's density, a 50 ml measuring cylinder is filled with the milk sample. A calibrated thermometer is inserted into the milk to measure its temperature, as the temperature can affect the lactometer reading.
Validation
All tests are validated to ensure the methods elicit the desired response. For example, detergent is inten- tionally added to the sample and checked for response.
The survey results indicate that starch and detergent, two common milk adulterants, were absent in any of the tested samples. This suggests that, at least for the tested samples, these harmful substances are not being used in Imphal region, ensuring a level of safety for consumers.
The absence of starch and detergent is a positive indicator of the general quality of milk, but vigilance is still necessary for other adulterants.
However, the milk density test revealed a varying degree of density across the different samples. Kongpal Dairy, with a density of 1.020g/ml, exhibited the lowest density, which is an indicator of possible highest water dilution. The other samples, though not as diluted as Kongpal Dairy, still showed variation in density, which may impact the nutritional quality of the milk.
The significant variation in milk density calls for more stringent monitoring of milk quality, as dilution practices can affect both nutritional values and consumer trust.
This preliminary survey lays the foundation for ongoing, broader studies and more robust milk safety regulations in the region, aimed at protecting public health.
Further studies should explore other possible adulterants and involve a larger sample size to comprehensively assess the milk quality across more diverse sources within Imphal. Establishing a regular surveillance program is essential to ensure consistent quality standards and to safeguard consumer health.