FOOD week 6-2 Postharvest management and quality of Food

Factors Affecting Taste and Quality

• Different cultivars exhibit varied taste profiles influenced by genetic and environmental factors.
• Cool temperatures slow down the filling process of banana fruit, impacting sweetness and texture.
• In citrus fruits, potassium nutrient levels increase acidity, affecting flavor.
• Internal dryness in Imperial mandarins is primarily caused by water stress or environmental conditions.
• Juice sacs in mandarins suffering from internal dryness can become shriveled, leading to poor texture and taste.

Temperature Management

• Postharvest temperature management does not include liquid nitrogen as a method.
• Optimal temperature for chilling insensitive produce is typically around 0°C to 5°C.
• Regions with warmer climates are more likely to have chilling sensitive produce, such as tropical and subtropical areas.
• The arbitrary threshold temperature distinguishing chilling sensitive from insensitive produce is 10°C.
• Factors not part of the transport cold chain include padding materials that don’t contribute to insulation.

Organic Acids and Storage

• Organic acids like citric and malic acids are stored in the vacuole of fruits and vegetables, impacting flavor and preservation.
• Damage to the tonoplast can lead to the leakage of compounds from the vacuole, negatively affecting fruit quality.

Ethylene Management

• Ethylene absorption is achieved using methods such as active packaging to slow down ripening.
• Fruits like tomatoes and avocados benefit from ethylene treatments for uniform ripening.
• 1-Methylcyclopropene (1-MCP) is a common ethylene inhibitor used to delay ripening and fruit drop.
• Ethylene's concentration over 0.1 µL/L can detrimentally affect the shelf-life and quality of produce.
• Continuous systems utilizing ethylene scrubbers are being integrated into active packaging solutions.
• Aminovinylglycine (AVG), marketed under the trade name ReTain, delays ripening and drop in certain fruits.

Pigmented Phytochemicals

• Chlorophyll contributes to the green color in plants.
• Carotenoids, including beta-carotene, cause red/orange pigmentation.
• Xanthophylls are responsible for the yellow coloration in fruits.
• Anthocyanins create red, mauve, blue, and purple hues in various plant tissues.

Ripening and Quality Changes

• Yellowing of bananas during ripening is attributed to the breakdown of chlorophyll and other pigments.
• Enzymatic browning in fruits and vegetables is triggered by polyphenol oxidase activity.
• Transportation damage in fruits and vegetables is commonly linked to mechanical impacts and bruising.
• The unique shape of certain fruits, like avocados, complicates their postharvest handling.

Structure and Texture

• Firmness and texture in fruits and vegetables are closely associated with cell wall composition and integrity.
• Primary cell walls are composed of cellulose, hemicellulose, and pectin.
• Enzymatic and mechanical processes modify cell wall structure during ripening, influencing texture.
• Water loss in produce during storage leads to wilting and decreased quality, impacting visual and taste attributes.

Flavor and Aroma

• Two main factors dictating fruit flavor include sugar and acid composition.
• Gas chromatography-mass spectrometry (GC-MS) analyzes volatile compounds, providing insights into ripe fruit flavor.
• Diacetyl contributes buttery notes, while furaneol adds sweet, caramel-like flavors to fruits.
• Ripe fruit may contain hundreds of volatile compounds that contribute to its distinct flavor and aroma.
• Flavor synthesis processes for aroma volatiles are heightened during the ripening stage.
• Time elapsed from harvest to consumption can significantly influence the flavor profile of fruits and vegetables.
• Off-odors during postharvest handling can arise from spoilage processes, impacting overall quality.
• Flavor tends to have a shorter shelf-life than visual appeal, often deteriorating before appearance.