6. Quality
7.1 Introduction
The best available definition of quality was one stabilised in the 1951 USDA Marketing Workshop Report. This definition alludes to quality being a concept, but describes it in terms that are definable in their own right. Quality was defined as being ‘a combination of attributes or characteristics of a product, which have significance in determining the degree of acceptability of the product to a user’. Because this definition mentions characteristics or attributes, which can be defined, and mentions a user, who will purchase the product or use the service, let this be considered a working definition of quality. Do not forget, however, quality is a concept. Building a quality program involves a long-term commitment of time and resources. Management should, however, look at their quality efforts not as expenditure, but as a cost-savings centre. The benefits of producing and distributing products of the same consistency or quality are enormous. Failure to maintain standards can result in severe economic loss, or, depending on the product and problems encountered, injury or worse to the user, and in the worst-case scenario, the economic death of a company or label. The essential elements of any quality program may be broken down into the following elements: ? Management support, ? Solid quality philosophy/policy, ? Communication/education, including Free exchange of information; employee self improvement; written procedures; specifications and standards; and professional societies and meetings, ? Committed staff/team approach, ? Independent quality management function, ? Process control/documentation, including product and raw materials specifications; packaging materials specifications; equipment maintenance; product coding, tracking, and recall procedures; and microbiological procedures and standards, ? Innovation Each of these elements is dependent on the others for successful program development and management. Quality control of fragrance and flavour substances, as well as the products derived from them, comprises the comparison of sensory, analytical, and if necessary, microbiological data with standards and specifications. To a large extent these have been established in official specification collections (Pharmacopoeias, ISO, Essential Oil Association, Merck Index). In the past few decades, a precise analytical methodology has been developed for sensory evaluation and has proved to give reliable results. Analytical determination of identity purity aids greatly in establishing the acceptability of fragrance and flavour materials. Single fragrance and flavour compounds are characterised by generally accepted physical constants, such as density, refractive index, optical rotation and melting point. The advantages of these parameters are their speed of measurement and the possibility of comparison with other laboratories; therefor, they will continue to be indispensable. Determinations of content by chemical parameters, such as ester and carbonyl numbers, are being increasingly supplemented by chromatographic procedures such as GC and HPLC and by spectroscopic techniques (UV, IR, and NMR). Standardisation of specifications for complex fragrance and flavour materials, such as essential oils and animal secretions, is far more difficult than for single compounds. In addition to organoleptic and physical properties, the content of certain typical components is determined. Problems concerning the natural, using modern chromatographic and spectroscopic analytical techniques (and combinations such as GC-MS) solves botanical and geographical origins of these products. The analysis of trace components (halogens, heavy metals, and pesticides) in flavours and fragrances that are used in foods and cosmetics is becoming increasingly important. Radioactivity values in materials of natural origin are also monitored. 7.2 sensory analysis After the past fifty years sensory analysis of foods has grown from a informal ‘taste test’ performed by bench top chemists and product developers to a science comprising basic tenets, accepted methods, and defined statistical analyses. The scientific literature of sensory analysis comprises investigations of sensory processes (the way we respond to physical stimuli), methodological studies of ‘taste testing’ (how to assess reactions to food products in a test situation), and statistical experimental design (how to set up systematically carried formulations of product). The actual physiology and psychophysics of the sensory systems involved in the sensory analysis (viz, taste, smell, touch, and appearance) are discussed in TRENDS IN FOOD SCIENCE AND TECHNOLOGY, VOL7, Nº12 DEC.1996. Data about the physical characteristics of food belong to the domain of food science. Sensory analysis is the nexus where these different disciplines join. There are essentially five different types of problems in which sensory evaluation is a necessary technique: -New product development -Cost reduction exercises -Quality improvement -Evaluation of product acceptance -Quality control and assurance. When presented with a sample for sensory evaluation, the test controller may have several well-defined aims in view. The controller may wish to: -Establish and characterise changes which may be either natural to or induced in the product -Distinguish between different samples -Ascertain whether some defined quality attributes can be expressed in terms of a simple numerical scale or index -Whether the total activity of the sample can be expressed in a simple or multidimensional manner so as to rank different samples -Establish standards and specifications -Grade samples with on without references to a standard sample -Establish a relationship between objective and subjective test data -Establish the hedonic values of the product Based on these two types of judgement, there are three main categories of sensory assessment: -Difference testing-usually carried out by a small panel of assessors (judges) not necessarily having great experience -Rating into categories- usually carried out by a panel of well-trained and experienced assessors -Acceptability appraisal-may be carried out by panels from small local groups to vary large consumer panels. These, preferably, should not include trained technique staff whose judgements may be unduly biased and unrepresentative of the majority. The easiest approach to sensory analysis for both practice and theory divides into four major subject areas: -Descriptive analysis. The language of food and drink, and how we describe our perceptions. -Intensity measurement. Perception of the sensory characteristics of foods on a scale, which shows how we process physical stimulus magnitudes to generate sensory responses. -Hedonic measurement. Our likes/dislikes. -GC sniffing analysis. Descriptive analysis At the heart of sensory analysis lies the complex field of language or descriptive analysis. While at first blush it may seem easy to describe a food, individuals familiar with a specific food use many terms to describe the fine nuances. Some of these terms are idiosyncratic, but many are standard terms easily understood. There is no single descriptive language of general and universal application, but rather attempts to capture on paper and numerically the elusive character of different foods. Since ancient times researchers have tried to create standardised lists of terms by which to summarise (and classify) sensory perceptions. Researchers using any of these lists soon find that the set of terms in any list is unbalanced and necessarily incomplete, comprising too many unusable terms for the specific product being studied, but too few relevant terms to capture the key ‘note’ or attributes. Human beings use as stretchable ‘rubber bag’ of terms to describe each product. The number of terms grows or shrinks to fit the specific product, but the list for any product may be sure to contain terms that would never be found in a general list. People process a constant amount of ‘information’ when they describe products. When forced to describe a wide range of qualitatively different products during a single test panellists overlook or jettison the nuances and focus on the more general terms that differentiate this broad array of qualitatively different stimuli. For products which vary only slightly from each other (e.g., different samples of strawberry aroma) panellists employ the more rarely used terms, focusing on the minor differences and highlighting them with these terms. Examples of attributes for a variety of Odorants are: Eucaliptus Bananalike Strawberrylike Sewer odour Buttery Burnt rubberlike Stale sooty Like burnt paper Geranium leaves Corklike Crushed weeds Cologne Urinelike Lavender Rubbery (new rubber) Caraway Beery (beer like) Cat-urinelike Bakery (fresh bread) Orange (fruit) CedarWoodlike Barklike, birchlike Oak wood, cognaclike Household gas Coconutlike Roselike Grapefruit peanut butter Ropelike Celery Grapejuicelike Violets Seminal, spermlike Burnt Candle Eggy (fresh eggs) Tea-leaflike Like cleaning fluid Mushroomlike Bitter Wet wool, wet dog Cardboardlike Pineapple (fruit) Cadaverous, like dead animal Chalky Lemon (fruit) Fresh cigarette smoke Maple (as in syrup) Leatherlike Dirty linenlike Nutty (walnut, etc.) Seasoning (for meat) Pear (fruit) Kippery (smoked fish) Fried fat Apple (fruit) Stale tobacco smoke Caramel Wet papperlike Soup Raw cucumber-like Sauerkrautlike Coffeelike Grainy (as grain) Raw potatolike Crushed grass Peach (fruit) Raisins Mouselike Chocolate Laurel leaves Hay Peperlike Molasses Scorched milk Kerosene Examples of lists of terms used in the description of Vanilla extract are: Flavour characteristics of pure Vanilla extact (these descriptions reflect the norm, flavour quality does vary between lots.) Flavour character Bourbon Beans Java Beans Tahitian Beans Vanillin Slight Very Slight Slight Resinous/leathery Slight-Moderate Moderate Very Slight Woody Slight Moderate Very Slight Pruney Slight Very Slight Very Slight Fruity Very Slight None Moderate Chocolate Very Slight Very Slight None Smokey-tobacco None Moderate None Bourbon-rummy Moderate Very Slight Slight Sweet-floral Very Slight None Moderate Measurement of perceived intensity Intensity measurement (quantification) comprises the second major application of sensory analysis. Quantification takes many forms, including determination of threshold, assessment of discrimination ability (the smallest physical change between two samples that is just noticeable), and scaling the suprathreshold intensity (how strong does the stimulus seem). Hedonics - measurement of liking Acceptance measurement, the third branch of sensory analysis, may well be the most vital aspect. We select and eat foods on the basis of their visual appeal and palatability. A large and growing body of scientific literature has been published on the measurement of acceptance. Appropriate measures of liking or purchase intent, and the assessment of possible consumer boredom with a product and critical issues when applying hedonic tests in the world or commercial research. GC sniffing analysis Aromatic extracts of foods are composed of more than one hundred volatile compounds, but the profiles obtained after GC analysis with electrochemical detectors do not necessarily reflect their aromatic specificities. Some of the compounds, present in large quantities, are not relevant to the overall aroma. Others, with low detection thresholds, are detected after GC sniffing, Whereas electrochemical detectors fail to give any response. For these is defined the Aroma value that is the ratio between the concentration of a compound and its threshold. These compounds are responsible for the aromatic characteristics of the food. As a result, sensory methods are needed to allow identification of the main aromatically active compounds and have investigated by different authors. There are two methodologies to do GC sniffing analysis: replace the electrochemical detector with a trained sensory panel that smells the aroma-active region directly from the GC effluent (aromagram); or sniffing the aroma fractions collected from the effluent. The second method more complicated but it allows the identification of fragrances constituted by two ore more compounds. Interpretation of results The results of many of the descriptive and affective sensory methods described can be studied by tabling the data, including the score of each judge for each sample, the means, the ranges, and the deviations from the mean. Some of the variability in results is attributable to the samples themselves, and may be a combination of differences in the raw materials and in the method of preparation. Sources of error in the judging include variability in the performance of one judge on duplicate samples as well as variability among several judges on the same sample. After the data have been tabulated and averaged, the answer to the question posed by the experimenter may be obvious and further analysis unnecessary. A study of the data such as described above is not adequate when the investigator wishes to state with confidence that the results obtained are statistically significant. In this case, a statistical analysis of the results is necessary. The original experiment should have been planned with statistical analysis in mind, because it is difficult, and sometimes impossible, to apply statistical to a completed experiment not appropriately planned. References have been given to tables based on statistical analysis for several discrimination and descriptive tests. Various methods of testing the significance of differences among means may be used depending on the experimental plan. Analysis of variance, with a multiple range test when appropriate, is very useful in many cases. Correlation, or an indication of the relationship between two variables, can be calculated between descriptive sensory data and objective data. Access to data handling and statistical analysis software for personal computers or to mainframe computers may facilitate data handling and analysis. The development of software for direct computer entry of data by panellists and the subsequent analysis by personal or mainframe computer will facilitate this process. Experimental Design Sensory analysis has achieved its major commercial impact by providing reliable test results from panellists. When coupled with experimental design and modelling (by regression analysis), sensory analysis becomes a powerful tool to guide product development. An alternative approach beyond directional scales to develop products using consumers, consists of systematically varying the formula ingredients in a way which allows one to assess the effects of each ingredient, and the interactions among ingredients on acceptance and attribute perceptions. Experimental designs are properly the province of statisticians. Sensory analysts and product developers have used experimental designs with great success to understand consumer reactions to test prototypes comprising known ingredients and processes. Product categories amenable to these designs range from simple food systems such as a fruit-flavoured beverage, to complex systems such as pizza, apple pie, and sausage. In all cases the assessment of systematically varied alternatives has educated the researcher and provided concrete direction for product modification. Using the Product Model to Assure Quality The product model relates independent attributes (under research or production control) to dependent variables, be these consumer ratings, expert panel ratings, etc. The product model plays a role in assuring quality, because it can be used in two distinct ways to control production: 1. Process Control. At the most basic level sensitivity analysis reveals how process or ingredient variations affect liking. Once the desired formulation has been located within the grid of alternative formulations, and the range of independent variables set (high to low for each independent variable), the investigator computes the sensitivity curves for each independent variable, holding the other independent variables fixed (at the prescribed level for production). The changes in the sensory ratings show how the independent variable affects the sensory character of the product (viz, sensory attributes). The change in liking indicates how changes in the independent variable affect acceptance. Quality control tables based upon sensitivity analyses highlight those independent variables, which produce noticeable sensory changes, and the degree to which those changes generate acceptance changes in their wake. The manufacturer should maintain tighter control over the key critical variables (perhaps at greater cost) and maintain looser control (at lower cost) over the less important variables (where departure from the optimal or production specifications do not reduce acceptance nor affect sensory integrity). The approach is consumer driven, because it is based upon the reactions of consumers to actual variations of the product, rather than hypothesis of what production variables might be important. It might well turn out that some variables play little or no role in determining acceptance, and can either be reduced to save money, or ignored by quality assurance over a wide range of levels. Conversely, more attention would then be paid to those important variables which influence acceptance. 2. Batch Analysis. The inter-relation among formula variables, consumer responses, instrumental variables, expert panel responses, and quality control panel responses assures quality at the production level on a batch-to-batch basis. Experts measure each batch, either, by the quality control panel, or by instruments. The measurements generate a goal profile. The goal profile determines a corresponding set of estimated ingredients or process variables, which would generate that profile. Once the levels of the independent variables are estimated the model estimates the corresponding consumer sensory profile and / or the likely acceptance rating. As each batch emerges from the production line quality assurance can calculate the expected difference from the reference or “gold standard” on a sensory or acceptance basis. At the time of the measurement, plant personnel decide whether the product is sufficiently similar to a target standard (or reasonably acceptable) to warrant shipment, or whether the batch must be reworked (or even discarded). Bibliografia HEATH, H. B. 1981. Source Book of Flavours, The AVI Publishing Comp., Inc., Westport, Connecticut. HUI, Y.H. (ed), Encyclopaedia of food science and technology, John Wiley and sons, 1992, 2410-2418: 2641-2657. PENFIELD, M. P., CAMPBELL, A. M. 1992. “Experimental Food Science.” Academic Press, New York Evaluation Sensorielle, Manuel Méthodologique, Association de Coordination Technique pour L’Industrie Agro-Alimentaire, Technique et Documentation - Lavoisier, 1990 Trends In Food Science and Technology, Vol.7, Nº12 Dec.1996