By: Dr. Nurul Izzah Khalid

Senior Lecturer

Faculty of Food Science and Technology, UPM

Figure 1: Bernoulli’s Principle Illustrated in Liquid Food Processing and Spray Drying.

 

Modern food manufacturing depends heavily on the controlled movement of liquids such as milk, juice, sauces, syrups and liquid concentrates. Behind every neatly filled bottle and every spoonful of instant beverage powder lies a carefully engineered system of pumps, pipes, valves and nozzles. To design and operate these systems efficiently, food engineers and food technologists rely on a core fluid mechanics concept: Bernoulli’s Equation.

 

Bernoulli’s equation describes how energy in a flowing fluid is distributed between pressure, velocity and height. In a simplified form for incompressible fluids, it states that along a streamline, the sum of pressure energy, kinetic energy (related to velocity) and potential energy (related to elevation) remains approximately constant, provided there are no major losses. Practically, this means that when the velocity of a fluid increases—for example, as it passes through a narrower section of a pipe—its static pressure tends to decrease. This fundamental relationship helps explain and predict how liquid foods behave as they travel through industrial equipment.

 

In food plants, this principle appears in many everyday operations. When milk or juice is pumped from storage tanks to heat exchangers and filling machines, changes in pipe diameter, height and flow conditions will influence both the speed and pressure of the liquid. If these factors are not properly balanced, problems such as cavitation in pumps, uneven heating, or unstable filling can occur. By applying Bernoulli’s equation during design and troubleshooting, engineers and technologists can ensure smoother flow, protect equipment and maintain product quality.

 

Figure 1 visualises several key applications in one simplified schematic. On the left, a section of pipe narrows, causing the liquid velocity to rise as it approaches a filling nozzle. This represents how Bernoulli’s principle is used to design bottle-filling operations so that beverages flow quickly enough to maintain production capacity, yet gently enough to minimise foaming and product loss. At the centre, bottles on a conveyor are filled with milk, illustrating the moment where controlled flow meets packaging. On the right, a spray dryer system shows liquid concentrate being atomised into fine droplets before being dried into powder. Here, high-pressure liquid is forced through a nozzle, converting pressure energy into kinetic energy and creating a high-velocity jet that breaks into droplets—another direct application of Bernoulli’s equation in food production.

 

In addition to efficiency, understanding fluid behaviour supports food safety. Stable, predictable flow is essential for processes such as pasteurisation, where each droplet or film of product must reach the target temperature for the required time. It is also important for Cleaning-In-Place (CIP) systems, where cleaning solutions must flow at appropriate velocities and pressures to remove residues and biofilms from internal surfaces. While Bernoulli’s equation is usually combined with friction-loss and rheological considerations—especially for non-Newtonian foods like sauces and slurries—it remains a useful starting point for designing hygienic, energy-efficient processing lines.

 

Ultimately, Bernoulli’s equation may look like a simple formula on paper, but in practice it helps bring together safety, quality and efficiency in liquid food processing. From the moment a liquid product leaves the storage tank until it becomes a filled bottle or a dry powder, this principle quietly underpins the decisions made by food engineers and food technologists on the factory floor.

 

References:

 

Zeki, B. (2018). Food Process Engineering and Technology (3rd ed.). Academic Press.

Date of Input: 19/12/2025 | Updated: 19/12/2025 | nur_jasni