Fruite, Veg and Herbs Flashcards
Fruit and Veg characteristics
High water content (80-95)
Dry matter is mostly carbohydrates
Alive tissue
Fruit and veg vitamins
Water soluble - cytosol - C, and B (folate)
Fat soluble - membrane and plastids - Vitamin A precursor, Vitamin K1
Phytochemicals
Acids
Aromas
Colorants
Types of acids
Citric
Malic
Both used in krebs cycle to regulate pH
Types of aromas
Terpenes - essential oils, fat soluble
Esters - acid and alcohol
Types of colorants
Carotenoids
Anthocyanins
Tannins
Carotenoids
Orange and Red
Long chain terpenes, membrane of plastids
Anthocyanins
Red, purple or blue
Large phenolic compounds
Water Soluble
Tannins
Colourless but become brown after enzymatic oxidation
Volatile Terpenoids
Lipid-soluble molecules made of isoprene units
Sticky and often toxic in large amounts, deters insects
Flavour in mint, thyme and other leafy herbs
Glandular trichomes on tomato leaves - gives colour so if you pick you can get yellow fingers
Volatile esters
Small molecules produced by epidermal cells in flower and fruits
Usually pleasant, attractive flowers that are not toxic
Carotenoids
Orange food
Anthocyanins
Belong to flavonoid class of phenolic compounds As it has an aglycon backbone with various sugars and acids
Types of polyphenols
Hydroxybenzoic acid Hydroxycinnamic acid Flavanoid Chlorogenic acid Stillbenes Lignans
Browning from polyphenol
Polyphenol oxidase polymerise phenolic compounds into brown melanin’s in the presence of oxygen
Melanin Formation Pathway
Monophenol
Diphenol
Quinone (condensation)
Melanins
Polyphenol oxidase enzymes
Monophenelase
Diphenelase
Example of browning Polyphenol
Apple juice
Immediately after pressing apple juice it is mostly white a frothy by 3 minutes mostly turned to brown colour
Bitter taste receptors
Receptor T2R family Activated by alkaloids Tannins Mycotoxins Isothiocyanates Toxic at high temperatures
Sour taste receptors
Enter cell undissociated of H+ proton channel (not a receptor)
Measures pH
Detects microbial spoilage or non-nutrients like oxalic acid
Why do we taste bitter and sour
Protect us against toxic or spoiled food
Aversive effect - intake of unfamiliar food (Involved in food neophobia)
Aversion lessons if repeat exposure
Aversion increase if experience nausea
Things to consider when transporting fresh produce
Minimise losses
Slow down respiration to extend shelf life
Prevent senescence process
Prevent rot or mould development
How to control respiration during transport
Cool produces to reduce metabolic rate
Lower oxygen in the atmosphere to reduce metabolic rate
Issue with cooling fresh produce
Temperature to cold can lead to to chilling injury (flesh browning)
Normal air
78% nitrogen, 21% oxygen and 0.04% CO2
Modifying atmosphere
Respiration in almost closed container increases amount of CO2
Inhibits respiration
Carbohydrate stores in plant are extended
Effect of ethylene production
Causes a snowball effect so start producing more ethylene
Leafy veg and ethylene
Negative effect
Wilt and turn yellow
Less sweet and more bitter
Dormant vegtables
Positive effect
Sprouting inhibited
Storage life extended
Non-climacteric fruit
Positive effect
Improved resistance to disease
Improve shelf life
How to minimise ethylene
Delay ripening
Treat sensitive products with ethylene action inhibitor 1-MCP
Package - prevent exposure
Control concentration
How to delay ripening
Temp, O2 and CO2
Ethylene scrubbers
