Sensory Properties Defect Flavor PDF

SENSORY PROPERTIES OF FOOD  DEFECTS A defect is a feature of a visual character that significantly affects quality in the eyes of the consumer. Imperfections, due to the absence of something necessary for perfection, or the presence of something that distrac...

SENSORY PROPERTIES OF FOOD  DEFECTS A defect is a feature of a visual character that significantly affects quality in the eyes of the consumer. Imperfections, due to the absence of something necessary for perfection, or the presence of something that distracts from perfection. In grading foods for defects, tolerances may be established in terms of maximum numbers of defective units allowable, such as number of discolored kernels in a can of corn.  DEFECTS Lack of any of the features that make up the food or the presence of negative factors such as lines or spots that will spoil the whole food. Texture disorders caused by disease in foods Changes that occur as a result of negative effects on products for various reasons (such as processing, transportation, storage) Differences due to foreign substances  Classification of Defects Genetic-physiological defects Entomological defects Pathological defects Mechanical defects Extraneous or foreign material  Classification of Defects Genetic-physiological defects They occur as a result of hereditary abnormalities of the raw material. Structural: Misshaped or misshapened pieces due to the abnormal growth of the crop. Malformation in strawberries, crooks in cucumbers, hollow stem in cauliflower. Off-color: Abnormal growth and coloration of tissue cells. It is seen in seed type crops. Character: Degree of development of certain tissues or plant parts, excessive development of some parts.  Classification of Defects Entomological defects: Insects cause these defects. The damage may be direct, as a result of the insect’s own activities such as feeding or stings, or it may be indirect caused by a disease organism introduced into the crop by the insect. Holes and scars, lessions, off- coloring and curled leaves  Classification of Defects Pathological defects: Produced by the action bacteria, fungi, mold or viruses. Structurally, the crop may be disfigured or deformed. The defects may appear externally only on surface in the form of lessions or off-coloring. Hidden defects may occur as internal defects as off-coloring, corky tissue, mold and rot.  Classification of Defects Mechanical defects Result from damage to the product of a physical nature. The degree of damage may be regulated by care in handling and by proper adjustment of equipment. Bruising of the tissue, pulled kernels, crushed pieces, cuts and slices can be given as examples to mechanical defects.  Classification of Defects Extraneous or Foreign Material: Harmless: Leaves, stems, buds, seeds Harmful: Stones, particles of glass or metal  Objective Methods Used in Defect Measurement Improving Visibility Dilution: It is used for liquid products and defects can be observed more easily in the product diluted with water. Using a white background: dark parts of the material spread on a white background can be easily identified Color change: red apple peels can be easily noticed when yellow-green apple juice is illuminated with red light.  Objective Methods Used in Defect Measurement Standardization of the control conditions: Control conditions are standardized in terms of factors such as sample sizes, sample container, light amount and intensity, and duration, and defects can be easily detected. For example, defects in a material that exhibits plastic type fluidity can be detected by using a device that can spread the material in homogeneous thickness.  Objective Methods Used in Defect Measurement Comparison with reference standards: In this method, the defects in the sample are compared with the identified defects. For this purpose, photographs, graphics or colored models are used to define the defect and the defects are determined by comparing them with the sample.  Objective Methods Used in Defect Measurement Determination by counting and measurements: In some cases, the defect or defect units are simply counted, and in some cases, the size and quantity of the defect is measured. The main tools used to detect defective units are plastic or metal disks or squares with various numbers of holes and sieves. Thus, defects detected with the help of holes or sieves can be easily and systematically determined. For this purpose, electronic scanning devices developed to automatically detect defects in products such as ketchup and applesauce are also used.  Removing the Defective Substance Flotation: Defects are floated using liquids such as water, oil or gasoline. For example, leather or similar lightweight items float on the water; Seeds, oil or insect parts are removed by floating on the surface of gas oil. Washing: Stone particles, core, etc. High density substances such as are removed from the environment by precipitating in water or different liquids. Electronic separation: In cases where the defect unit varies in color depending on the product, defective samples can be separated automatically using an electronic device. For example, such devices are used to distinguish yellow and green peas from each other.  Internal Defects In some cases, although the product looks completely perfect on the outside, it may contain significant defects on the inside. Internal rots seen in potatoes and apples can be given as an example of this. These types of defects can be detected by increasing the light frequencies in the visible or dense visible region, as they usually differ in optical density from the defect-free part. Radiospect is an example of a device developed for this purpose.  New Techniques Used in Defect Measurement Computer imaging, ultraviolet, near infrared, infrared and fluorescence imaging techniques, ultrasonic method, X-ray method and nuclear magnetic resonance method are used as new techniques to detect defects in foods. These methods are techniques that enable the internal and external properties of products to be examined objectively, quickly and without harming the analyzed food.  New Techniques Used in Defect Measurement Ultrasonic method is based on measuring the vibration provided in the system by using mechanical waves at a frequency of 20kHz and above. The vibration created in the system helps determine the different physical properties of the product. Since the generated ultrasonic waves will move at different speeds depending on the density difference in the product, the change in product properties can be easily determined.  New Techniques Used in Defect Measurement X-ray method, which is one of the techniques used to determine physiological defects in fruits and vegetables without damaging the product, is widely used to determine internal defects. The nuclear magnetic resonance method is based on obtaining information about the molecular structure of the product by analyzing it under a strong magnetic field. Characteristics such as ripeness and rot in fruits and vegetables can be determined by this method.  FLAVOR FLAVOR= TASTE + ODOR (AROMA) Flavor is generally defined as a phenomenon that consists of the combination of the concepts of taste and smell, but also includes pain and temperature stimuli.  FLAVOR The pain and temperature are mouthfeel characteristics and are characteristics that affect flavor. Since mouthfeel features affect the kinesthetic properties of foods as well as flavor, this feature is located between flavour and kinesthetic in the Kramer circle.  Characteristics of Taste and Odor Compounds Taste Compounds Odor compounds Perceived by tongue Perceived by nose Non volatile More or less volatile Polar and soluble in water More or less polar Found in relatively high concentrations Found in low concentration Salty, sour, bitter, sweet, umami A lot of odor compound  Taste Taste stimuli are perceived by taste receptors on the tongue. Taste receptors are located in taste buds, and each taste bud consists of 50-150 taste cells. Taste buds are located on the papillae (epithelial protrusions) on the tongue.  Taste When the receptor cell is stimulated by a taste substance, the normal electrical charges that exist between inside and the outside of the cell are changed and this change activates the attached nerve which then sends electrical nerve impulses as its message to the brain. Physiology of taste  Taste Sweet, salty, bitter and sour tastes are perceived in different areas on the tongue. In recent years, sweet, salty, bitter and sour tastes, as well as umami taste, have been considered basic tastes.  Objective Methods Used in Measurement of Taste Characteristics Sweetness: Sweetness can be measured instrumentally by total sugar analysis and by refractometers in pure solutions of syrup Sourness: Sourness can be measured instrumentally by total acidity analysis and by pH meter in pure solutions Saltiness: Cl determination by titration, Na determination by flame photometer Bitterness: There isn’t any general method for determination of bitterness. Different methods are used for specific components. For example: caffein in tea (spectrophotometric, HPLC) piperidine in black pepper (spectrophotometric, HPLC, GC) Umami: MSG is determined (spectrophotometric, column chromatography, HPLC)  ODOR Odor is sensed by the odor (olfactory) receptors in the nose. The area controlling the sense of smell is located in upper part of the nasal cavity, known as the olfactory area.  ODOR There are over 10 million olfactory receptors in a very small area of the posterior region of the nose. Each of these receptors has cilia that enter the mucos covering the olfactory epithelium. The odors stimulate cilia and initiate changes that lead to a change in the electrical potential of the olfactory receptor, which in turn initiates the electrical nerve impulses transmitted over the olfactory nerve to brain. Olfactory Nerves BRAIN receptors Odor source Physiology of odor perception  ODOR The smell prism by Henning is used for the classification of odors. Fragrant Putrid Ethereal SMELL PRISM Spicy Burned Resinous Henning’s smell prism  ODOR It is known that there is a relationship between odor quality and molecular weight, volatility and chemical structure. Certain chemical structures or groups create characteristic odors (e.g. esters, amines, fatty acids, etc.). The odor feature is limited by the molecular weight, and the odors of compounds with a molecular weight of more than 300 cannot be detected. Compounds of similar series have similar odors, and the odor intensity increases with a certain chain length.  ODOR The odor has great importance in the food industry and the problems it causes are more than the taste feature. Some of the problems encountered in the food industry due to odor can be listed as follows: Odors of fish, meat and milk residues produced in factories processing protein products Odors due to storage time, temperature, or improper packaging Odors that cause a decrease in the quality level of food, such as moldy bread, rancid oil, rotten meat, etc. Odors caused by the use of preservative additives such as sulfur dioxide, sorbic acid and benzoic acid The development of the desired odor in the controlled ripening of fruits, wine and cheese over time is a positive example of the importance of odor in food production. ODOR  OBJECTIVE METHODS USED IN FLAVOR ANALYSIS The most commonly used technique for objective evaluation of flavor is Gas Chromatography. In addition to gas chromatography, studies on the application of the electronic nose device in flavor analysis are continuing. Gas chromatography is used for three purposes in flavor analysis: Identifying compounds Determination of the product Flavor acceptability  Identifying Compounds Gas chromatography is widely used in the qualitative and quantitative analysis of flavor substances in foods. In flavor determination by gas chromatography method, volatile compounds in the food sample are passed through the chromatography column with the help of a carrier gas. Since the retention times of each compound in the column are different, these compounds exit the column for different periods of time and are detected with the help of a detector. Pure standards are used to determine flavor substances qualitatively and quantitatively. For qualitative determination, the retention times (Rf) of the components are compared with the retention times of the standards. Peak areas are compared for quantification.  Determination of the Product A particular peak in the gas chromatogram can be decisive for a product and that peak can be used to determine adulteration in the product. For example, the determination of the flavor substance called cis- hexanol in the black tea chromatogram shows that the tea is Ceylon tea.  In this application, gas chromatography, which is an objective method, is used together with subjective sensory evaluation techniques. For this purpose, first of all, flavor compounds are Flavor determined in gas chromatography of the food sample. Acceptabili ty Pure standards of the detected flavor components are presented to the panelists in different concentrations and they are asked to rank or score according to their preferences. The presence of a statistically significant positive correlation between the peak area of ​the flavor substance and the preference rankings or scores of the panelists reveals that the substances in question are effective in flavor acceptability.  Flavor Acceptability 21 specific compounds were isolated in the tea aroma. Peak of cis-hexanol was determined as Ceylon tea aroma. This data is used to determine whether the tea is Ceylon tea or not. However, the presence or absence of cis-hexanol in tea has no relationship with the taste acceptability of tea. Linalool peak was determined as the compound affecting the flavor acceptability of tea.  Electronic Nose The electronic nose is a device that can be used in determining flavor compounds in foods, as well as in quality control applications in the food and beverage industry, in the pharmaceutical industry and in diagnosing some diseases. The electronic nose, a device that uses electronic sensors as a chemical detection mechanism and neural networks as an identification mechanism, was developed by imitating the human nose. E TONGUE