Sensory Physiology

1. Introduction

Sensory analysis depends on the human senses of sight, hearing, smell, taste, and touch.

Each food has a certain appearance, smell, texture, taste, temperature, makes a certain noise when we bite into it, etc. These so called stimuli are perceived by our sensory organs, the eyes, nose, mouth, skin, and ears. Each organ has receptors for corresponding stimuli, meaning we can see the colour of a tomato, but not how it smells or hear how sour or sweet it is and so on. Each receptor receives a particular stimulus and moves it along the nerve system to the brain, where the received stimulus is processed into information about the food that is being eaten.

Each organ has its own sensory system, which in scientific terms are called the visual system (sight), olfactory system (sense of smell), gustatory system (sense of taste), somatosensory, tactile, and thermoreceptive system (sense of skin- or mouthfeel, touch and temperature), auditory system (hearing).

All senses work together to create a complete impression of the food. How each stimulus is perceived and judged often depends on the fit of the received stimuli with each other and our expectations.

We expect a certain texture, smell and flavour of a red tomato. If it does not meet our expectations we might just be pleasantly surprised or disgusted. The role of our sensory systems is to ensure we can detect foods, which could be potentially hazardous, because they are poisenous, unripe, rotten or contaminated.

Another function of our gustatory system (taste) is to identify carbohydrate (sugar-rich) or salty (NaCl-rich) foods, which are essential for energy balance and cell function. Perceived smell and taste also trigger the release of digestive enzymes and gastric acid to prepare for the digestion of the food that is being eaten.