The rest of the course Flashcards
Which are the 5 most common food colour additives in Sweden?
Caramel, beta-carotene, Annato extract (carotenoid), anthocyanins and vitamin B2 (riboflavin)
Name some natural colors
Tetrapyrroles (heme, chlorophylls), Terpenoids (carotenoides), Flavanoids and betalanines
What give the red color in meat
The conjugated double-bond, also the oxidation state of iron
What happens to myoglobin when reacting with oxygen and nitrite and when it is oxidized and heated
Oxygen + myoglobin becomes oxymyoglobin which is Bright red. When this one is heated it becomes methmyoglobin which is Brown. When myoglobin is oxidized it also creates this Product. If both methmyoglobin and myoglobin is treated with NO it turns into a nitrosomyoglobin which is Bright red.
Which two compounds can make meat red
CO and NO
In which way do the partial pressure of oxygen affect myoglobin
The larger the oxygen partial pressure, the more oxymyoglobin. Where the oxygen is low (where plastic touch meat) there is high levels of methmyoglobin. Where it is none oxygen the deoxymyoglobin is present which give a Purple red color (vacuum pack).
How is the chlorophyll affected as a color?
It has a Mg in the middle (as heme has iron). If this is lost it becomes Brown; often in pH <6. If the pythol Group is removed (enzymatic) it becomes more hydrophilic and stable.
What can be done to preserve the green chlorophyll color
Higher pH, High temp/short time processing, transform to chlorophyllide (E140) or substitute the Mg to Cu (Boston gurka, Wakame)
Name some commonly used terenoids
- carotenes (lycopene- red in tomatoes, beta-carotene- orange n carrots)
- Xanthophylls (Lutein- yellow in egg yolk, astaxanthin- yellow egg yolk and salmon, bixin)
Describe the properties of terpenoids
Yellow to orange/red, soluble in lipids, sensitive to oxygen, radicals and light (oxidation)
Name a common flavanoid, the a
Anthocyanidins: give a red/blue/lilac color in blueberry and a lot of other berries and fruits. Affected by pH. At low it is red (and if oxidized it becomes colorless). When the pH increases it goes to violet (neutral) and lastly blue when basic.
What effect do sulfite have on anthocyanins
When sulfite binds it creates a colorless compound. The red color can be preserved by adding other polyphenols that bind to same Place as in red wine/cocktail cherry. White wine have sulfites (can be used to bleach red wine stains)
Name Another flavonoid, the p
Proanthocyanidins: colorless but easily oxidized to red-brownish color
Whats the properties of condensed tannins
Give a brownish color and in nature they occur in polymers, first detected in cocoa beans, ability to precipitate proteins: give that dry taste, inhibit metals (coffee inhibit iron uptake), antioxidant. Often present in tea.
Describe the properties of betalaines
red, heat sensitive, sensitive to oxygen and light - becomes brownish, not so affected by pH
Name a common synthetic colour
Azo-colours: used with restrictions, some are banned in the EU because of the effect in Children
Whats the defintion of vitamins
a Group of organic compounds, 13 recognized in human nutrition, essential in small amounts
Which vitamins are fat-soluble
Vitamin A, D, E, K and caretenoids
Which vitamins are water soluble
VItamin C and B
Whats a vitamer
a compound with similar biological properties to Another but some diff. exists in the chemical structure, ex. retinol (Vit. A), ergo- and colecalciferol (vit. D)
Whats a provitamin
a naturally occuring compound which can be converted into a vitamin by normal body metabolism, ex caretenoids
Whats a problem when analyzing folic acid
Only the reduced form can be detected
Name some precautions taken when sample prep. before analysis
Yellow light, homogenize the sample, do not use Stainless steel, nitrogen gas to prevent oxidation
Which analyze method is used for B6
There exists man diff. variants so you need to homogenize all so not all 3 needs to be detected. Detect by HPLC (fluorescence detection)
Whats the basic concept of Confocal microscopy?
gives 40% better Pictures than light microscopy, Project laser light and through flourescence the sample can be seen
Whats be basic concept of Transmisson electron microscopy?
Have an extensive sample prep since water and fat needs to be removed Works in a high vacuum system were electrons is focused on the sample
Whats the typical structure of ice cream
It has air bubbles inside that are stabilized with polysaccharides to prevent collaps. The fat+casein stabilizes as well.
Name a few roles polysaccharides can have in food
Thickener, gelation, fibre, water management, stabilizer, energy, aroma+taste, appearence, controlled release (drugs) etc.
Describe the typical structure of a gel
It consists mainly of water, have a 3 dimensional network of gel strands that are connected in junction zones (can be ionic and hydrogen bonds). Ions, pH, temperature etc. affect the gel.
Whats the basic structure of starch
It’s a mixture of linear and branched chains of glucose, amylose and amylopectin.
Whats the properties of starch granules
between 20-25% amylose and rest is amylopectin. See Picture… Amylase is in the amorphous region and amylopectin in the crystalling where a lot of branching. With alpha, beta chains. The granules can look different in maize, wheat etc.
What happens in gelation
The hydrogen bonds are broken during heating and the crystalline structure of amylose and amylopectin is lost. If this viscous solution is cooled the linear part of amylose retrograde and rearrange themselves again to a crystall structure. has become a starch gel.
What is retrogradation
It can expel water from the polymer network, this process is known as syneresis.
What happens when the bread is staling
Happens especially to refrigirated bread. Moisture and amylose migrate out of the starch granules, degelatinizing the starch. Amylose and amylopection realign themselves causing recrystalisation, resulting in harder texture.
What is resistant starch?
Starch that is resistant to digestion, found in raw potato and unripe bananas
What happens when repeated heat/cool cycles and stirring
water comes out and the stability is decreased. increased stirring lower the viscosity
What is pectin
a polymer tha appear in most plants. the polymer have smooth hairy regions. The smooth can create junctions but not the hairy. The degree of methylation is important. It is strongly hydrating and at neutral pH it is partly ionised which means the pectin repell each other
Describe the gealtion of highly methylated pectin
Sugar is needed as dehydrating agent. The pH needs to be lowered to remove the ionized pection regions COO- -> COOH, so that they do not longer repell each other. The smooth regions crystallize and form junctions.
What is needed for low methylated pectin gelation
Ions such as Ca2+ and low pH. Once again the positive ion help the ionized pectin to come together. Also called the egg box model where the Ca2+ is surrounded by the polymer with negative charges
What is alginate
Comes from Brown algae. consists of poly-M and poly-G sequences. The g sequence consists of guluron acid segments which is capable to form the egg box model with Ca2+. The M is mannuron acid. The M/G ratio is crucial for the viscosity and gelation.
What is Carrageenan
From red sea weed. Mainly consists of 2 different forms of galactose and sulfate Groups with ester bridges. It is sensitive to ions since it is a charged biopolymer. Prone to form double-helices and can form termoreversible gels in the presence of positive ions.
Name some uses of carrageenan
Thickener, stabilizer, gel formation, in dough, ice Cream, drinks and 36% vispgrädde
Name some uses of alginate
Does not melt below 100, makes it useful in many Products. gives firmness in ice Cream and texture and counteracts the formation of large ice Crystals. helps gluten in dough, stabilizer, thickener agent, foam stabilizer in beer.
Name 3 gums and some applications
Xanthan, Gellan, Guar. Can be used as thickener, stabilising emulsions, smooth texture Products, dietary fiber.
Whats good about using TEMT
TEMT=Transmission electron microscopy tomography. Can be used to visualize 3D structures. Created as the sample is tilted from +70 to -70 degrees and pic taken every degree.
Whats the definition of a food additive
Any chemical whether natural or synthetic which is not normally taken as a food or consumed as a food. Instead they are added to food Products to enhance quality or other properties.
What is an E number
E number are codes for substances that are permitted to be used as food additives within the European union.
What regulation are there for food additives
An additive can only be approved for the specific food in question, the approval is never general to all Foods.
What includes the free rule
Compounds that have been extracted from animals or plants through drying, heating, leaching with water or mechanical treatment (do not apply on colorants), NaCl, sugars, acetic acid or ethyl alcohol and non-toxic essance or aroma for flavour or taste enhancing
What is EFSA
The European Food Safety Authority in the EU responsible for risk assesments regarding food and feed safety. Provides scientific advice and clear Communication on risks. It is responsible to evaluate new and re-evaluate food additives. Also responsible for the Acceptable Daily intake (ADI) for each substance.
What is JECFA
The Joint FAO/WHO expert Committee on Food Additives. Is an international expert scientific comittee that is administrated jointly bu the Food and Agriculture Organization (FAO) and the World Health organization (WHO)
Describe the role of E 200 - Sorbic acid
Inhibit the growth of moulds and yeast and C.Botulinum that exists in bacon and fish. Works best at lower pH. The mechanism is that microorganisms cannot degrade sorbic acid thus inhibits the dehydrogenase that normally degrade fatty acids in the organism. Often added to juices, jams, low-fat margerine. Mixed into Product or on Surface or package
Describe the role of E 210 - Benzoic acid
Benzoic acid is converted to Hippuric acid in the kidney and extracted by the urine. Inhibits yeast and bacteria, works best at low pH. Naturally occuring in lingonberry, plums, cinnamon. Often added to juices, jams, margerine
Describe the role f E 220 - Sulfur dioxide
The antimicrobal (yeast, mould, bacteria) effect increases at lower pH - it is assumed to be sulfur dioxide in comple with water. Also inhibits enzymatic/non-enzymatic browning, enzyme activity and has antioxidative as well as reducing properties. Often used in production of dried fruits and vegetables, fruit juices, syrups and wine. Some are sensitive to this, it is excreted in the urine. It reacts with acetalaldehyd in the cell, inhibit NAD in electron transport chain and breaks disulphite bonds in ezymes.
Describe the role of E 250 and E 251 - Nitrite and Nitrate
Inhibits microorganism (C.botulinum) and stabilizes myoglobin in meat (red color) where it is converted to nitrosomyoglobin (still red when heated).Though it can have toxic effects when they turn into nitrosamines. NO2 can bind to hemoglobin and block the oxygenation (problem for Young Children, do not give spinach)
Organic acids as additives?
Buffering agents, CO2 release from baking powder, inhibit growth of Micro organisms and can act as chelating agent. IT inhibits Micro organ. by it’s effect on the pH and chemical properties. It has a chelating effect by complexing metal ions that will otherwise act on oxidation, miscoloring etc. Some are EDTA, citric acid, acetic acid, lactic acid.
How does organic acids help baking powder
It reacts with the sodiumbicarbonate to water and CO2. The reaction is strongly related to temperature and varies with type of H-donor.
Whats the difference between a toxin and toxicant
A toxin is a poisonous substance produced by a living organism and a toxicant is created artificially
What happens in the body when toxins are absorbed
The liver is trying to dtoxificate it. Trying to turn fat soluble toxins into water soluble so they can be excreated in the urine. If they cannot be eliminated in the body they can bioaccumulate which is dangerous in the long run as the conc. increases.
How are toxins evaluated?
Ames test, cellular models where light is used to see damage to cells, animal studies and human. After that the ADI can be calculated (the safety factor is included which is animal value/100)
What does ADI stand for
Acceptable Daily intake
What does NOAEL stand for
No observed adverse effect level, can be compared to LOAEL
What does TDI stand for
Tolerable Daily intake
What can happen if you mix alcohol with paracetamol
An enzyme in the live can convert paracetamol into a conjugated form which is harmful.
What classification are there of toxins in foods
- Endogenous toxins - natural Component of the food
- Microbial toxin/mycotoxins - produced by contaminating moulds and bacteria
- Toxic residues - unintentional pesticides, fungicides, Heavy meal residues
- Toxic contaminants - from cooking, food processing such as nitrites, acrylamides
Describe Solanine and chakonin
It’s an endogenous toxin and a glycoalkaloid. In green potatoes because of mechanical damage, sprouting or exposure to light. Cause nausea, diarrhoea and stomach pain. It can also be a neurotoxin, leads to muscle contraction.
Describe Caffeine
Mainly found in coffee, tea and chocolate. In one cup of coffee there is about 50-125 mg (LD50 10 g/day). It works as a stimulant (increase blood pressure, heart rate, insomnia, nervoussness), diuretic effect. Induce more release of adrenalin and noradrenalin. Absorbed in the small intestine and the highest blood conc. is after 1-2 h after drinking. half Life about 3-7 hours. Endoenous toxin
Comfrey ?
Endogenous toxin that is normally produced by plants as protection against insects. Can be present in milk, honey and herbal tea. Another name for these are Pyrrolizidine alkaloids, which are phototoxic Chemicals, i.e. toxic when exposed to light after metabolism. Can be carcinogenic, cause vomiting, dizziness, abdominal pain, Death and liver damage.
Whats the toxic effect of amines?
Vasopressor amines - normal Product of amino acid metabolism. It is produced by microorganisms in fermented Foods. Some people are sensitive to these or cannot metabolize them. Can cause hypertension (high blood pressure), migraine (choclate), IBS.
Describe Lectins
Available in dry beans, sioy beans and chick peas etc. therefore needs to be cooked. Can distress the digestive system and cause nausea, diarrhea, bloating. Can also damage intestinal wall cells.
What are Cyanogenic glycosides?
Present in raw Cassava, apple seeds, bitter Almonds, raw cashew. Can cause acute cyanide intoxication that result in dizziness, vomiting and collapse (or even death), can in long run result in goiter, tropical ataxic neuropathy and konzo.
What are mycotoxins
Natural contaminant from moulds (Aspergillus, Fusarium, Penicillium). They are heat stable and toxic in low concentration. Often on nuts, corn/weat, fruits. Can be cancerogenic, immunosupressive, diarrhoea and impaired kidney function.
What is Aflatoxin
A mycotoxin which is the most potent of all toxins produced by Aspergillus flavus. Can grow up to a aw of 0,75. Can be present in peanuts, pistachios, Brazil nuts. Can be screened for because they flourescence. Can cause accute liver toxicity, highly carcinogenic, hepatitis B, immune suppression. Can sometimes be found in milk.
Botulism?
A microbial toxin produced in anaerobic conditions. A neurotoxin found in honey and home canned food. Inhibits acetylcholine which can result in paralysis and organ failure. denatured by heat.
Staphylococcus aureus is bad because?
Cause vomiting, diarrhea, fever, cramps. Produces several diff. enterotoxins with diff. resistance to heat. Can be found on ready sandwiches, pre-peeled eggs.
Name some toxic residues
- DDT - pesticide, bioaccumulating, endocrine dsruptive activity
- Antibiotics - can result in resistant bacteria
- Metylmercury - can be found in fish, bioaccumulating, neurotoxin
Nitrosamines are bad because..
It’s a toxic contaminant that can be synthezied in the stomach by nitrite in Foods. Nitrites can be found in vegetables (spinach). Amines can be found in protein rich Foods. Can also be a process contaminant in bacon, smoked food, latex etc. In animal studies they were carcinogenic, linked to gastric cancer in humans. Ascorbic acid and tocopherol can decrease the levels.
How does the taste, smell sense work in humans
Food and Beverages generate signals in receptors in the nerve systems periphery. The signals are sent to the brain (CNS) where they are processed and interpreted. All senses interact to create the impression.
How does the taste and smell sense work together
The molecules stimulate our senses and the molecule reacts differently with nose and taste receptors. Ex. cinnamon taste and smell differently! Taste is only sweet, sour. etc!
Where are the taste receptors situated and what are five basic tastes?
they are located in the taste buds. Sweet, Sour, Umami, Bitter, salt. Some people lack the bitter gene. The receptors for the diff. tastes are different. The important mechanism behind how they work is equlibrium. acid/base, salt/not salt
What are the different stimulation mechanism of the tastes?
Sour&salt: reacts to ions Na+ and H+
Sweet&Bitter: stimuli reacts with receptor that are bound to G proteins. So its a enzymatic reaction. Sweet Closes sour channels and opposite.
Umami: similar mech. to sweet/bitter
Name a few artificial sweeteners
Sorbitol (E420), Maltitol (E965), Isomaltitol (E953), Xylitol (E967), Aspartame, sucralose. Usually not absorbed by the body
What is the degrading Product of Aspartame
Methanol when pH is below 7
What is the degrading Product of Sucralose
When heated it can give rise to off-flavour products
Name two common bitter compounds
Quinine (tonic water) and caffeine
What is meant by astringency and how can it be prevented
the “dry” feeling. Often in wine, tea, unripe bananas. Polyphenols bind to salive proteins so that the salive production is lost. Can be reduced by adding lemon juice or milk.
Whats the mechanism of the trigeminal nerve system
Free nerve endings in the mouth and nose that can feel coolness, pungency (hotness,spice), irritation and pain. Cause tears and nasal secretion.
Name some pungency compounds and where they are found
Chilli (capsaicin), Pepper(piperine, ginger (gingerols and shogaols)
What can happen when glucosinolates are broken down?
nitiles can be formed at low pH and the pungent isothiocyanate can be formed.
Describe our sense of smell
Our olfaction center s a small area at the top of the nasal cavity that can sense VOC. Most odours are blends and we can sense up to 10 000 odours.
Whats the hedonic charcter
If its good or bad/nauseating
What is anosmia
odour blindness, cannot identify smells
What is hyposmia
Reduced odour perception
what is dysosmia
confuse odours
Which are the two pathways to stimulate smell
Orthonasal (through nose, breathing in) and retronasal (from mouth after swallowing, breathing out)
How can food odours be analysed
GC-sniff (chromotography + olfactometry) and isolation of volatiles through distillation, extraction etc.
What are the peaks in an chromatogram
The retention time - when compounds start becoming volatiles
Name some challanges of odours
They have different threshold, an odour is often a mixture of compounds, isomers can smell completely different.
