Presentation on theme: "The role of organoleptic inspection in food qualification"— Presentation transcript:
1The role of organoleptic inspection in food qualification
2Food quality components: Food hygiene propertiesPhysical propertiesChemical propertiesPacking and labellingOrganoleptic propertiesExterior characteristics: surface, colour, packing, shape, formOdourTasteTemperatureSubstance and structure
3Organs eyes, nose, tongue and mouth, fingers, ears(!) Using the human organs of senses as measurement tools raises some problems:the human organs of senses are liable to sensorial errorsthe human organs of senses are fatigablethere is a big biological variabilitysome bitter substances could be percepted only in higher concentration by some peoplesome people are sensitive to the chumestrol-content of the carrot
4Sense of Taste~6 million receptors on the tongue (dynamic balance), with aging death>production of receptors → ~1,5-2 million4 basic tastes (sweet, salty, sour, bitter), but there are some more tastes:taste generating pain sensation (capsaicine)taste influencing the sensation of substance characteristics (alkaline materials or contractive materials like alum)metallic taste (FeSO4×7H2O)the “umami” taste (complex taste, the taste of Na-glutamate; it’s salty, sweet, bitter and metallic at the same time)Haller’s taste catalogue contains 12 basic tastes (for example there is taste generating changes in heat perception – menthol)
5Sweet tastenatural (sugars; mollenin – 2000 times sweeter than sucrose; miraculum – changes the taste effect: makes sweet from sour)artificial (sugar-alcohols, ketones, esters, etc.) – they were developed during the research of diabetesIntensity of the sweet taste increases with water-solubility.Making symmetric structure from an asymmetric, the sweet taste changes into bitter
6Sour, salty taste Sour taste: acids Depends from: acid concentration, pH, dissociation rate, other food components, the buffer effect of salivaIntensity: acetic acid (the least intensive)→lactic acid→malic acid→citric acid → tartaric acid (most intensive)Around the perception threshold (0,02g/100cm3) the typical salty substances (like NaCl) seem to be sweet, they appear to be salty only around recognizing threshold (0,08g/100cm3).
7Salty taste: salt like materials substancetasteMgCl2salty-bitterK2SO4sour-bitterNH4Clsalty-sourBeSO4sweet-sourNaHCO3salty-sweetPb-acetatesweet (!)MgSO4bitter-sweetSalts of heavy metalsmetallic
8Bitter tasteSubstances containing nitrogen, anorganic salts, tanning materials, alkaloids (caffeine, quinine, morphine, nicotine), etc“Taste blindness”: some people (and monkeys) don’t percept the bitter taste.
9Factors influencing personal values of taste sensing threshold pH of the sampletemperature of the sample (no refrigeration temperature!)clearness of the aroma substancethe water mediumsize of the tongue surfacenumber of receptors on unit surfacePhysical and psychical condition of the judge (judge has to know his program 2 days before the inspection – no coffee, smoking, big breakfast at the morning,etc.)Circumstances of the inspection (noise, light, temperature, colour of the wall, etc.)part of the day (a.m. is the best – between hours)experience of the judge (Can be learned and improved by practicing)method of the inspection (drop-method, spoon-method, etc.)other factors
10Sense of Smell Aroma: odour (in mouth) + odour (in nose) + taste Scent: pleasant smellSmell materials: common characteristics are: the –OH, –CO, –COOH or –NH2 groupFactors influencing the sense of smell: temperature (optimal: 25-30°C), part of the day (a.m.), age (20-40 years), sex of the judge (female), smoking (no), experience (high)Anomalies of the sense of smell:hypozmia: decreased sense of smellhyperozmia: hyper sensitivity (women)anozmia: no sense of smell (above 80 years of age)merozmia: no perception of specific smellsautozmia: sensation of smell without smelling substance
12Choosing the judges: examination of tasting-, smelling- and colour recognizing abilities Recognizing the tastes:Sour: citric acidBitter: caffeineSalty: NaClSweet: sucroseUmami: Na-glutamateMetallic: FeSO4×7H2Odistilled watermethods:draught methodspoon-test (more exact definition of amount)drop-test (3 on the tongue – it’s the best; usually it turns to ridicule
13Recognizing the smells: stable smell :ammoniabitter almond smell: benzaldehidesweat smell: butyric acidVinegar: acetic acidnail polish smell: amyl-acetatehospital smell: phenolVanilla: vanillinbutter aroma: DiacetileAnise: anetolemethod: put cotton-wool in a bottle, drop 0,5 cm3 of substance on it
14Recognizing the colours Ishikawa-test (ophthalmologic sight-test)-10 bottle dilution series of 3 basic colours (red, yellow, greenish-blue); should be put in order
15Faults in judgments: perceptional: for example attractive packing expectional: positive prejudicehabituation: too high number of samples, with little differencescontrast: too big differences between samplessettle: the judge uses the middle values in judging by pointstolerant approach: in case of favourite product
16The perfect judge:has to have normal organs of senses, healthy, rested, with positive approach, curious, compliant, teachable, conscientious, capable, concentrated, calm, well-balanced, free from prejudice, critical, self-critical, reliable, disciplined, accurate, self-confident, unimpressionable, with good sense of phrasing, qualified
17Methods of organoleptic inspections One test: the sample is compared with a standard sample. First step: examination of the standard sample, then this standard is removed. Second step: examination of samples (there are standard samples and samples to be examined in the sample series). The judges have to differentiate the samples from the standard samples. Advantage: the sample series can be examined however long. Disadvantage: the samples have to be compared with a vision of memory.Duo-trio test:Tetrad test: 2 kinds of samples in 4 pots signed with codes. Aim: which two are the same.Two from five test: 5 pots: sample No1 is in 2 pots, No2 in 3 pots.Pair test: there are 2 kinds of this test:Differentiation of two samples: is there a difference between A and B? (The “no difference” answer should be allowed.)Indication of the direction of the difference (Which is more intensive? Which is better?, etc.)
18Descriptive organoleptic inspections The judgment should be made by an expert of the specific sample/product. The sample is compared with standards (Codex Alimentarius, International standards, etc.).There are two kinds of properties which should be examined during the comparison:positive characteristics, which should be presentdisqualifying characteristics, which should not be presentThe presence/lack of positive and disqualifying characteristics should be detailed in the result.Decision: passed, not passed.
19Methods for quantitative analysis Extended examination of differences:Description ScaleGrading: the samples are put in order on the basis of a specific property, then a grade point is given.3) Judging by points:a) 100 points, point subtraction scaleb) 5 points, weighting scale (or 20 points scale)Every property can obtain 5 points, the different importance of the properties is weighted with factors (the factors’ sum has to be 4, so the sum of points obtained will be 20).Usually 4 properties are examined: appearance, odour, taste and substance
20Other methodsMatching together a concentration with sensation: for example: comparing a sweetener (saccharin) with different sugar-solutions. Result: which concentration of sugar-solution generated the same sweet taste perception as saccharin?Pouring method: for example: we pour clear water to concentrated sugar-solution, and we try to find the concentration which generates the same sweet taste perception as saccharin. If it’s found → we measure the sugar-solution’s concentration with refractometry → Result: “The sweetener (saccharin) is as sweet as a … concentration sugar-solution.”Consumers’ judgements:Popularity surveysScales:scale of popularityObserving the consumersExamination of focus groups