Food Commodities: Yoghurt

Yoghurt: Nutritional and Dietetic Value

Nutritional Value of Yoghurt

Types of Protein

• High-Quality Protein: Yoghurt provides a significant amount of high-quality protein, including both casein and whey protein, which are essential for growth, repair, and maintenance of body tissues.
• Amino Acids: It contains all nine essential amino acids necessary for human health.

Types of Fat

• Varied Fat Content: Yoghurt comes in full-fat, low-fat, and fat-free varieties. The fat in yoghurt is predominantly saturated but also contains some monounsaturated fats.
• Omega-3 Fatty Acids: Some yoghurts, especially those made from the milk of grass-fed animals, may have higher levels of omega-3 fatty acids.

Vitamins and Minerals

• Calcium: Rich in calcium, essential for bone health.
• B Vitamins: Particularly high in Vitamin B12 and riboflavin (B2), supporting energy metabolism and red blood cell production.
• Probiotics: Many yoghurts contain live bacteria, beneficial for gut health.

Other Nutrients

• Phosphorus and Magnesium: Contributes to the maintenance of normal bones and teeth, and supports muscle function.
• Zinc: Supports immune function.

Dietetic Value of Yoghurt

Probiotics

• The live bacteria in yoghurt can improve gut flora balance, aiding digestion and potentially reducing gastrointestinal issues like constipation and diarrhoea.

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Food Commodities: Yoghurt

Protein Content

• The high protein content in yoghurt can increase satiety, potentially aiding in weight management.

Low-Calorie Option

• Low-fat and fat-free yoghurts are low in calories, making them a good choice for weight control diets.

Calcium and Vitamin D

• High in calcium and often fortified with vitamin D, yoghurt supports bone density and health.

Added Sugars

• Some flavoured yoghurts can be high in added sugars.

Lactose Intolerance

• Those with lactose intolerance may experience discomfort; however, some find yoghurt easier to digest than milk.

Vegetarian Diet

• A valuable source of protein, vitamins, and minerals for vegetarians.

Sports Nutrition

• Useful for muscle recovery due to its protein and carbohydrate content.

Exam Focus: Questions and Answers

1. Discuss the nutritional value of yoghurt, focusing on its protein content.

Yoghurt is an excellent source of high-quality protein, containing both casein and whey protein. These proteins are crucial for body tissue repair and growth and provide all the essential amino acids required for human health. The high protein content of yoghurt also contributes to its satiating properties, making it a suitable food for weight management diets.

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Food Commodities: Yoghurt

2. Evaluate the dietetic value of yoghurt, including its role in gut health and bone health.

Yoghurt's dietetic value is particularly evident in its contribution to gut health, thanks to the probiotics it contains. These live bacteria help in balancing gut flora, aiding digestion, and enhancing the immune system. Moreover, yoghurt is a significant source of calcium, vital for bone health, and is often fortified with vitamin D, further supporting bone density and prevention of osteoporosis. However, individuals with lactose intolerance should approach yoghurt consumption cautiously.

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Food Commodities: Yoghurt

Production of Yoghurt

Production Process of Yoghurt

1. Homogenization

• Definition: Homogenization is the process of breaking down fat molecules in milk to create a uniform mixture.
• Purpose: It prevents the cream from separating from the milk, ensuring a consistent texture in the final yoghurt product.

2. Pasteurisation

• Process: Milk is heated to about 85°C for 30 minutes or 90-95°C for a shorter time.
• Goal: This step kills harmful bacteria and pathogens, making the milk safe for consumption.

3. Cooling

• Temperature Reduction: After pasteurisation, the milk is cooled down to about 45°C.
• Importance: This temperature is ideal for the growth of yoghurt cultures.

4. Adding Starter Culture

• Types of Cultures: Typically, a mix of Lactobacillus bulgaricus and Streptococcus thermophilus bacteria is used.
• Function: These bacteria ferment lactose, the sugar in milk, turning it into lactic acid.

5. Fermentation

• Process: The milk is kept at a constant temperature (around 45°C) to allow fermentation.
• Outcome: The lactic acid thickens the milk and gives yoghurt its distinctive tangy flavour.

6. Cooling

• Post-Fermentation: Once the desired acidity level is reached, the yoghurt is cooled to halt the fermentation process.
• Storage Temperature: It is cooled to about 5°C to preserve freshness and extend shelf life.

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Food Commodities: Yoghurt

7. Addition of Other Ingredients

• Flavourings and Sweeteners: Fruits, sugars, and flavourings can be added to enhance taste.
• Nutritional Additives: Some yoghurts are fortified with additional nutrients like vitamin D or probiotics.

8. Packaging and Labelling

• Containers: Yoghurt is packaged in various container types, from single-serve cups to larger family-sized tubs.
• Labelling: Packaging includes important information such as ingredients, nutritional value, expiration date, and storage instructions.

Exam Focus: Questions and Answers

1. Explain the importance of pasteurisation in the production of yoghurt.

Pasteurization is a crucial step in yoghurt production, where milk is heated to about 85°C for 30 minutes or 90-95°C for a shorter time. This process eliminates harmful bacteria and pathogens, ensuring the milk is safe for yoghurt making. It also stabilises the milk proteins, which is essential for achieving the right consistency in the final yoghurt product.

2. Describe the role of starter cultures in yoghurt production.

Starter cultures, typically consisting of Lactobacillus bulgaricus and Streptococcus thermophilus, are added to milk during yoghurt production. These cultures ferment the lactose in milk, converting it into lactic acid. This fermentation process thickens the milk and imparts the characteristic tangy flavour to yoghurt. The cultures also contribute to the probiotic content of yoghurt, beneficial for gut health.

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Food Commodities: Yoghurt

Yoghurt: Guidelines for Buying, Storing, and Uses

Guidelines for Buying Yoghurt

Types of Yoghurt:

Plain Yoghurt

• Unsweetened and unflavoured, rich in natural taste.

Flavoured Yoghurt

• Includes added flavours like fruit or vanilla.

Greek Yoghurt

• Strained to remove whey, thicker and higher in protein.

Set Yoghurt

• Cultured in containers, firmer texture.

Stirred Yoghurt

• Cultured in a tank and then stirred, creamy texture.

Low-fat and Non-fat Yoghurt

• Reduced or no fat content, good for lower-calorie diets.

Probiotic Yoghurt

• Contains live cultures beneficial for gut health.

Guidelines for Buying Yoghurt

Ingredients

• Opt for yoghurts with minimal additives. The basic ingredients should be milk and live cultures.

Sugar Content

• Check for added sugars, especially in flavoured varieties.

Expiry Date

• Ensure the product is within its best before date for freshness.

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Food Commodities: Yoghurt

Fat Content

• Choose based on dietary needs (full-fat, low-fat, or non-fat).

Organic Certification

• If preferred, look for organic certifications.

Probiotic Cultures

• For gut health benefits, choose yoghurts with live probiotic cultures.

Guidelines for Storing Yoghurt

Refrigeration

• Store yoghurt in the refrigerator at 4°C or below.
• Keep the yoghurt container sealed to maintain freshness and prevent contamination.

Shelf Life

• Observe the 'use by' date. Consume within this time for optimal quality.
• Once opened, consume within 3-5 days.

Avoiding Contamination

• Use a clean spoon each time to prevent bacterial contamination.
• Do not consume directly from the container if it will be stored again.

Freezing Yoghurt

• Freezing yoghurt can change its texture, making it less creamy.
• Suitable for frozen desserts but may not be ideal for other uses after thawing.

Culinary Uses of Yoghurt

As a Base for Dishes

• Smoothies and Beverages: Mix with fruits for smoothies or shakes.
• Dressings and Dips: Combine with herbs and spices for healthy dressings or dips.

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Food Commodities: Yoghurt

Cooking Ingredient

• Marinades: Acts as a tenderizer in meat marinades.
• Baking: Substitute for butter or oil in baking recipes.
• Soups and Sauces: Adds creaminess to soups and sauces without extra fat.

Desserts

• Frozen Yoghurt: A healthier alternative to ice cream.
• Toppings and Parfaits: Use as a topping for desserts or layer in parfaits.

Special Diets

• Vegetarian Dishes: A protein source in vegetarian meals.
• Lactose Intolerance: Some lactose-intolerant individuals

Exam Focus: Questions and Answers

1. What should you consider when buying yoghurt for a healthy diet?

When purchasing yoghurt for a healthy diet, look for products with minimal additives, low sugar content, and live probiotic cultures. Opt for organic and low-fat or non-fat options if applicable.

2. How should yoghurt be stored to maximise its shelf life?

To maximise shelf life, store yoghurt in the refrigerator at or below 4°C, keep it sealed, use a clean spoon for serving, and observe the 'use by' date. Once opened, consume within 3-5 days.