Lecture: Dynamics of food quality
- Quality is something that’s perceived by the consumer. Different consumers make different
perceptions.
- ISO 9000: “the degree to which a set of inherent characteristics fulfills requirements”.
- The Institute of Food Science: “the consistency of attainment of the specified
properties of the food”.
- The quality depends on intrinsic quality attributes and extrinsic quality attributes.
- Quality attribute: properties of a product that contribute to the perceived quality. Intrinsic
quality attributes: properties inherent with the physical product (safety, health, flavor).
● Extrinsic quality attributes: characteristics of the food production system or are
characteristics that are assigned to the product by communication (animal welfare,
sustainability, etc.).
● Food products as such have no quality - products have properties that influence product
attributes, which are perceived by the consumer as quality.
- In order to understand how to describe the expected quality by consumers, properties are
linked to food quality.
- The perceived quality depends on noticeable product attributes (smell, appearance,
taste). These attributes are broken down in intrinsic and extrinsic quality attributes. The
intrinsic quality attributes depend a lot on physicochemical properties (variable
composition, dynamics of composition, effect of processing). Extrinsic quality attributes
depend a lot on technological properties (process parameters, equipment, building &
facilities, environment). Technological properties are affected by personnel involved in food
production. Legislation affects the quality attribute by putting restrictions and requirements
on the product properties, technological properties and managerial aspects. Legislation also
affects the quality attributes directly by putting requirements on labelling of, for instance,
health claims.
● Maslow’s pyramid of needs states that different attributes are important at different levels.
● Food properties: Food safety - intrinsic:
- Safety: absence of hazards. A hazard is a potential source of danger that is present in a food
product. Those hazards can be microbial, physical or chemical.
● Biological: mainly involves microorganisms.
- Food infection: the pathogens themselves can cause an illness upon ingestion.
- Food intoxication: the pathogen can produce toxins while present in the food
product.
● Chemical: chemical hazards can be classified into:
- Food intoxicants: to which everyone who consumes the food is vulnerable.
- Food sensitivities: allergies and intolerances.
● Physical: physical hazards can be categorized into radioactive and non-radioactive.
- Safety is also related to risk: the chance of presence of a hazard combined with the severity
of the harm. As a producer you have to define what’s an acceptable risk.
● Food properties: shelf life - intrinsic:
- Shelf life: the time between production and the point at which it is no longer suitable for
consumption.
● Major shelf life limiting food processes are microbiological, chemical, enzymatic, physical and
psychological.
○ Microbiological → growth of spoilage bacteria/pathogens, toxin formation pathogens.
- Spoilage bacteria: form metabolites during growth → off-flavour.
, - Pathogens: pose a health risk.
○ Chemical → non-enzymatic deterioration, oxidation reactions.
○ Enzymatic → enzymatic reactions after cell disruption/in the intact product.
○ Physical → water/other compounds migration, phase changes, retrogradation of
carbohydrates.
○ Physiological → respiration (plants), ripening, transpiration.
● Microbiological and physiological reactions are most important in short shelf life products.
● Chemical, enzymatic and physical reactions are most important in medium-long shelf life
products.
● Food properties: flavor - intrinsic:
- Safety and shelf life are often taken for granted, whereas flavor is an essential element in
satisfaction with a product. It’s a satisfier.
- Flavor is the total sensory impression of food; it’s observed with all 5 basic sensing systems:
- Sight, smell, touch, taste, hearing.
● It should not be mixed up with aroma/odour.
○ Texture: the perception that derives from the structure and how the product behaves
when handled and eaten.
○ Odour: related to both volatile and non-volatile components. Odour compounds will
stimulate the olfactory receptors in the nose.
○ Taste: sweet, salt, sour, bitter and umami. Perceived taste is often influenced by
odour.
○ Appearance: size, shape, gloss, etc. For raw materials, it strongly depends on
seasonal differences, breeding practices and cultivar differences. For processed
foods, it depends on the recipe and production process.
○ Sound: mainly depends on the physical structure and composition of the product.
● Food properties: convenience - intrinsic:
- Convenience: anything that is intended to save resources or frustration.
- It’s related to ease-of-use or preparation before consumption. It’s related to packaging, but
also to pre-processing, so that preparation at home can be convenient and saves time. It can
be anything that
● Food properties: health - intrinsic:
- Health-related properties: are necessary for the body functioning and those that positively
contribute to well-being of the consumer.
- It’s related to a longer time-frame, than the other properties: the consumer has to trust that
the product improves health, upon consumption. This takes time → difficult to judge.
● Nutritional value: composition → macronutrients, micronutrients
● Health improvement: presence and/or addition of (active) compounds with specific
health objectives. Omega-3 fatty acids.
● Satiation: satiety (stopping with eating), satiation (how long it takes before eating
again).
● When it comes to extrinsic attributes, a sharp distinction can be made between people as a
citizen and as a consumer.
● They are often not directly related to the physicochemical properties.
● The compounds of which foods are made can be divided into 3 classes:
1. Nutrients: the amount and availability determines the nutritional value. Variability should be
taken into account for, for example, processing or labelling of the products.Variability strongly
differs per product type.
, 2. Additives: substances added to foods, mainly aimed at improving the quality of the food
products. Variability depends on the precision with which it is dosed in the product.
3. Contaminants: undesirable compounds that have entered the food system, mainly via the
environment and processing. Variability depends on different circumstances along the food
production chain.
- Dynamic food processes: microbiological, chemical, biochemical, physical and physiological
processes.
- Dynamics of food quality also includes underlined variation. Variation is not something that’s
expected by consumers. They expect a constant quality. Variation is thus detrimental to the
perceived quality, and must therefore be prevented!
- When a product has reached the consumer, it has gone through a number of steps in the
food production chain. In all different steps, quality may
start to differentiate, which may cause a different perceived
quality.
● Primary production: includes both animal and vegetable
production.
○ The primary production chain consists of the following
major chain actors: farmers, transporters &
slaughterhouses. For animal production, the 3 most
quality-influencing factors are:
■ Farming practices. Conditions on the farm
that influence the final product quality are:
breed, keeping (hygiene), feed and animal
health.
■ Transport. During transport animals can
experience stress, which might impact the
quality of the meat.
■ Slaughtering. Animals can also experience
stress. Good hygiene is required, of both the
skin & intestinal tract of the animal and the
slaughterhouse environment.
○ For vegetable production, the 3 most important steps are:
■ Cultivation: growing plants on the farm. Greenhouses are favorable.
■ Harvesting practices: harvest time and mechanical injury are important.
■ Post-harvest practices: practices in both transportation and storage.
● Processing:
○ Fermentation:beneficial microorganisms grow in the food product, increasing its
quality.
○ Separation & combination: the food is split into ingredients, or ingredients are
added to foods. Good hygiene is important.
○ Heating: heating of food products is done for two main reasons:
1. Ensuring safety of the consumer.
2. Increasing the shelf life.
○ Evaporation & drying: used to stabilize foods by removal of water.
○ Extrusion: makes use of starch gelatinization. It’s a combo of heating and drying.
● Packaging: main aim is to protect. It also provides convenience and information (labelling).
● Retail: critical factors are the time-temperature of storage and hygienic conditions.
● Finally, food quality depends on the consumer too. They should properly handle the foods
and follow the recipes.
