Pressed Candy OEM Quality Control: Friability, Disintegration and Weight Variation Limits
Quality control for pressed candy cannot rest on "looks fine and tastes fine". In real pressed candy OEM production, whether a batch is released depends on a set of measurable checks: weight variation, hardness, friability, disintegration, moisture and microbiology. They serve as the plant's internal controls and as the brand's objective acceptance basis. This guide walks through each one from a QC bench perspective - how it is measured, where the limit sits, and what to check first when a result fails.
1. Weight variation: the most basic and most easily lost
Weight variation reflects how stably the press fills the die. Routine practice is to sample 20 tablets every 15 to 30 minutes, weigh them and calculate the mean and relative standard deviation. Three factors drive it: powder flow, measured by angle of repose and Carr index; particle size distribution, since too many fines fill the die unevenly; and the match between feed-frame speed and fill depth. When variation runs high, check fines ratio and hopper level before touching the machine - a hopper below one third gives unstable fill pressure, the mistake beginners make most. Worn punches and powder build-up in the die bore widen the spread slowly, so both belong on the daily check list.
2. Hardness and friability: two parameters pulling against each other
Hardness is measured on a hardness tester, typically 40 to 80 N for pressed candy. Friability runs four minutes at 25 rpm in a friabilator, with weight loss not exceeding 1 percent. The two trade off: raise compression force and hardness rises while friability improves, but disintegration slows and capping may appear. The right setting sequence is to fix the target hardness band first, back-calculate compression force and fill depth, then confirm that friability and disintegration still pass - rather than chasing maximum hardness. Over-hard tablets also feel gritty in the mouth, which hurts the experience.
3. Disintegration time: tied to product positioning
Disintegration measures how long a tablet takes to break apart in water at 37 degrees. Ordinary pressed candy is usually required to disintegrate within 30 minutes; lozenges and chewables are exempt. The levers are disintegrant type and level - sodium starch glycolate, croscarmellose sodium, low-substituted HPC - plus compression force. When disintegration runs long, three causes cover most cases: over-compaction from excessive force, too much magnesium stearate, and over-mixing that coats particles with a hydrophobic film. Working through those three locates the problem in nearly every instance.
4. Appearance: judging defects on the floor
Appearance checks cover sticking, pitting, capping, soft tablets, chipped edges and colour spots. Floor practice is first-article full inspection, in-process sampling, and full inspection of the tail-end material. Slight colour drift between batches is normal because botanical extracts vary naturally, and the permitted range should be agreed in the acceptance standard up front. Black specks or foreign colour patches, however, require stopping the machine - usually incomplete cleaning between batches or scorched material in the drying step. Writing down where acceptable ends and stop-the-press begins keeps the line from arguing.
5. Moisture and microbiology: the hard release gate
Beyond sensory and physical checks, release needs chemistry and microbiology: total plate count, coliforms, mould and yeast, plus moisture, net content and marker compounds. Moisture matters most, since too much invites mould and too little causes capping. Pressed candy usually sits between 3 and 5 percent, depending on how hygroscopic the formula is. The common trap is testing only finished goods and skipping in-process material - once a finished batch fails, it cannot be saved. Well-run plants set an intermediate control point after blending and before compression to catch the risk earlier.
6. Put the numbers into the acceptance standard
When working with a plant, the brand should write these quantified limits into the sampling acceptance sheet and the contract appendix: RSD ceiling for weight variation, hardness band, friability ceiling, disintegration time, moisture range, microbial limits and the test methods behind each. With numbers agreed, "is this batch acceptable" stops being an argument. For the plant, aligning limits early avoids repeated machine changes during production that consume capacity and delay delivery, which saves money on both sides.
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About Guangzhou Mesen Health Biotechnology Co., Ltd
Guangzhou Mesen Health Biotechnology Co., Ltd is located in the Huashan Science and Technology Park, Huadu District, Guangzhou. The company has focused on OEM and ODM services for the big health industry for nearly 20 years, operating dedicated research, production, sales and management centres, and maintaining long-term strategic partnerships with well-known Chinese medicine colleges and research institutions. Capabilities span pressed candy, gummies, capsules, solid beverages, herbal teas, plant beverages, protein powders, dietary supplements and enzyme jelly - from formulation development through contract manufacturing. For details on minimum order quantities, sampling lead times and quotations, see our manufacturing advantages and product range, or contact us for a tailored proposal.
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