Starches
What is the molecular reason that amylopectin-rich starches resist retrogradation?
Amylopectin's highly branched chains interfere with the formation of hydrogen bonds that cause retrogradation
Why does honey resist microbial spoilage despite being a sugar?
Honey has a low water activity, which prevents most microorganisms from growing despite its high sugar content
What is one major limitation of sensory testing in food science?
Results can be influenced by individual preferences and environmental factors.
What is the primary role of proteins in foam formation?
Proteins reduce surface tension and form films around air bubbles, creating a network to hold water and air in
place
What initiates the Maillard reaction in foods?
A reducing sugar reacts with an amino acid under heat.
Which type of starch is preferred for frozen food products and why?
Starches high in amylopectin, as they resist retrogradation and syneresis, allowing the product to be frozen and thawed without developing a gritty,
crystalline texture.
What property makes sugar alcohols like sorbitol useful in diabetic-friendly products?
Sugar alcohols like sorbitol provide fewer calories and have minimal impact on blood glucose, making them suitable for diabetic products.
How can triangle tests contribute to product development decisions?
They help determine if a reformulated product is perceptibly different from the original.
Why are emulsifiers necessary in food emulsions?
They prevent separation by reducing interfacial tension between oil and water.
Normally, oil and water separate because they don’t mix well.
An emulsifier (like lecithin or egg yolk) surrounds droplets of one phase (like oil) and allows it to remain suspended in the other (like water).
This creates a stable interface, which is the thin layer where the emulsifier sits between the oil and water phases, reducing surface tension and preventing separation.
Why does caramelization require higher temperatures than the Maillard reaction?
It involves thermal degradation of sugar alone, not amino acids.
How does the ratio of amylose to amylopectin influence the texture of starch gels?
High-amylose starches form firmer gels; high-amylopectin starches yield softer, more stable textures
How does the Maillard reaction involve reducing sugars?
Maillard reaction occurs when reducing sugars combine with amino acids during heating, forming complex flavors and browning pigments.
What is the difference between hedonic and descriptive sensory tests?
Hedonic methods ask consumers how much they like a product, while descriptive analysis quantifies attributes such as flavor and texture
What causes syneresis in gels and how can it be minimized?
Syneresis, or liquid expulsion, occurs when gel networks over-contract.
How does pH affect browning reactions in food?
Lower pH slows Maillard browning, while neutral-to-alkaline pH enhances it.
How does sugar affect starch gelatinization
Sugar competes for water, thus delaying starch gelatinization and raising its onset temperature.
What sweetener is made by adding enzymes to corn syrup to increase fructose content?
High Fructose Corn Syrup (HFCS) - produced by enzymatic conversion of glucose to fructose in corn syrup, increasing sweetness.
What type of sensory test is best for new product screening and why?
Affective testing. Determines acceptability or preference between products.
How does gelatin concentration affect gel strength?
The firmness and elasticity of gelatin gels increase with gelatin concentration
What type of compounds are responsible for the aroma and color in Maillard browning?
Melanoidins and volatile flavor compounds.
Why is pregelatinized starch used in instant food products?
Pregelatinized starches swell in cold water and are used in instant products for quick thickening without heat.
Why does fructose promote browning more than sucrose in baking?
Fructose participates more readily in Maillard reactions due to its reactive carbonyl group, promoting faster browning than sucrose
How does controlled lighting help minimize bias in sensory panels?
It masks visual cues like color, keeping focus on taste and aroma.
How does temperature influence the stability of emulsions?
Elevated temperatures destabilize emulsions by disrupting the emulsifier-stabilized interface and increasing phase separation risk.
What makes non-enzymatic browning different from enzymatic browning?
Unlike enzymatic browning which involves polyphenol oxidase, non-enzymatic browning is due to chemical reactions like Maillard or caramelization