flour particle size analysis

Saturday February-07 2026  15:16:02

flour particle size analysis is a method and instrument used to determine the distribution and size range of flour particles, and is an integral part of flour quality testing. Flour particle size is mostly concentrated in the 20-150 μm range, with significant differences in particle size between different grades. Particle size analysis helps to understand the characteristics of flour particles, ensuring their stability during processing and consumption, and also facilitates flour grading and quality evaluation. Taking No. 00 flour as an example, its particle size is mostly between 20-80 μm. D10 is approximately 25 μm, indicating that 10% of the particles are smaller than this; the median particle size of D50 is approximately 45 μm, representing the average size of the flour particles; and D90 is approximately 75 μm, indicating that 90% of the particles are smaller than this, with the remaining 10% being slightly larger particles, resulting in a relatively uniform overall distribution. This analysis helps to avoid the negative impact of uneven particle size on processing performance or taste.

The Sieving Process for Flour Particle Size Analysis

Flour particle size analysis commonly uses sieving. First, lumps and impurities in the flour are removed, and a sample of a certain amount is weighed. Next, the sieving apparatus is set up, with sieves of different aperture sizes stacked from largest to smallest. The sample is placed on the top layer, and the apparatus is then covered and fixed to a vibrating sieve machine. The vibration frequency, amplitude, and time are set, and the equipment is started, allowing the flour to vibrate and sieve. After sieving, the flour from each layer of sieves is collected and weighed, and the quantity of each particle size is recorded. The proportion is then calculated to obtain the particle size distribution of the flour. The sieves are generally made of stainless steel, which is not easily worn and does not react with the flour. Typically, 4-6 layers of sieves are stacked, with apertures decreasing from largest to smallest, covering a particle size range of 20-150 μm. During operation, it is important to ensure the sieves are flat and well-sealed, the vibrating parameters follow standard procedures, the sample is weighed accurately, and any lumps are thoroughly broken up to ensure reliable results.

Flour Particle Size Requirements for Different Food Categories

Food Category	Particle Size Range (Typical D50 Value)	Recommended Flour Type	Core Function
Cakes, Biscuits (Shortbread)	40 - 60 μm	Low-gluten flour, fine and uniform particle size	Forms a porous crumb structure, ensuring a soft and crisp texture
Bread, Toast	60 - 90 μm	High-gluten flour, uniform particle size	Quickly and uniformly forms a strong gluten network to support volume
Chinese Noodles, Dumpling Wrappers	70 - 100 μm	Medium-high gluten flour, medium particle size	Forms moderate gluten, providing elasticity and chewiness
Pizza Crust	80 - 120 μm	High-gluten flour, relatively coarse particle size	Absorbs water slowly, extends fermentation, creates a crispy outer layer and chewy inner texture
Whole Wheat / Whole Grain Foods	Above 100 μm	Whole wheat flour, wide particle size distribution, contains bran	Provides dietary fiber, rich flavor and unique coarse texture
Frying Breading	Above 150 μm	Specially coarse granular flour	Forms a three-dimensional crispy crust and reduces oil absorption
Pre-mixed Powder, Soup & Sauce Thickener	Below 40 μm	Ultra-fine powder	Quickly disperses and dissolves, avoids clumping, delivers a smooth texture

Advantages of Flour Particle Size Analysis

Flour particle size analysis is relatively simple to operate, generally using sieves. The process is standardized, and flour mills or small laboratories can quickly learn it without complex training. The measured data is also relatively reliable. Combined with a vibrating sieve, it minimizes human error, and multiple measurements show little difference, making it useful for judging flour quality. The entire analysis process is short, taking approximately thirty minutes per sample, making it convenient to test multiple batches of flour on the production line. It is also cost-effective; the equipment is easy to maintain, consumables are easy to replace, and the sieves can be repeatedly cleaned and reused, saving considerable effort in the long run. Moreover, particle size analysis not only provides specific particle size figures but also visually shows the distribution of flour particles, providing clear results and valuable reference for production and quality management.

Applications of Flour Particle Size Analysis

Flour particle size analysis is widely used in flour quality testing and processing. It helps us understand the size and distribution of flour particles, providing a reference for flour grading, production process adjustments, and applications in different food products. In flour processing, particle size analysis can determine the suitability of the grinding process, adjust grinding roller parameters, and ensure that different grades of flour particles meet requirements, avoiding inconsistent product texture caused by overly coarse or fine particles. In baking and food processing, particle size affects flour water absorption, gluten formation, and expansion. For example, low-gluten flour used in pastries requires finer particles for lower gluten content and a softer texture; high-gluten flour used in bread requires a suitable particle distribution for a more stable gluten network. Particle size analysis also helps check for impurities or uneven grinding in raw materials and provides data support for formula development and compound flour adjustments.

Flour particle size analysis measures the size and distribution of flour particles, representing the characteristics of flour numerically. This allows companies to better control quality during production and uses this data for flour grading and pricing. The sieving method is simple, inexpensive, and provides reliable data, making batch testing convenient in factories. In practical applications, particle size analysis is used throughout all stages of flour production, from grading to pricing, helping companies adjust grinding processes to ensure uniform flour particles and consistent texture.