The Power of Steam: How to Remove Residues of Collagen from Metal Bowls

| By | Fedegari, Pharmaceutical Equipment

The pharmaceutical industry faces the challenge of developing an effective washing strategy for removing collagen from metal bowls. Fedegari performed trials in its R&D laboratory located in Albuzzano (Italy) using a GMP Eco-steam washer: steam was considered to soften the dry collagen and water was suggested to provide the mechanical action necessary for the complete elimination of the soil.

The Challenge

The challenge of the study was to find the most efficient washing strategy to be demonstrated by visual inspection at the end of the procedure. The development of an optimal washing cycle – composed of steam injection and hot water rinsing phases – focused on the complete removal of all the collagen residues in a stainless-steel bowl employed for pharmaceutical processing. In order to obtain the highest performances, Fedegari tested the application of an advanced eco-steam system to soften the dry collagen. In addition, specific mechanical actions with water were studied for the complete collagen elimination.

Materials and Samples Provided by the Pharmaceutical industry

  • A metal bowl dirtied with residues of collagen (see Fig. 4). A visual inspection of the inner surface revealed the presence of dry and sticky collagen with uniform distribution and a fibrillary morphology.
  • A sample of collagen to repeat the washing cycle under different conditions (e.g. temperature, time, etc.).

First Session of Trials:

General Information and Load Configuration

In order to design the best washing cycle for the complete removal of collagen from the surface, a preliminary study using stainless-steel coupons was carried out. Different coupons (10X10 cm) were prepared applying a mix of collagen and water (1:1) (Fig.1). After 24 hours, when the collagen has completely dried, the first washing trial was performed. As negative control, were used two coupons without collagen (see Fig. 1): so, it was possible to control that the purified water (2-6 µS conductivity) didn’t leave any salt residuals on the material.

During the first session of trials, the metal coupons were placed into a rack with 15° inclination. Then, the rack was placed into the washing machine (see Fig.2).

Figure 2: Load configuration for the metal coupons.

Cycle 1: Phases, Results and Discussion

A washing cycle was performed. The process was divided in two phases:

  • steam injection at 90°C for 10 minutes, to soften the dried collagen from the coupons surface
  • rinse with hot water at 88°C for 10 minutes, to mechanically remove the collagen from the material.

As shown in Figure 3, all the coupons, including the negative control, were considered effectively clean after a visual inspection. The use of steam injection and rinsing phase with hot water has proven to be effective to remove dried collagen from the coupons.

Figure 3: Metal coupons at the end of the cycle 1.

Second Session of Trials: General Information and Load Configuration

Following the positive results obtained with the steam injection and hot water rinsing, the same washing cycle was performed with the dirty bowl provided by the customer (see Fig. 4).

Figure 4: Bowl dirty with collagen provided by the customer.

The bowl was placed inside the washer on a metal support (see Fig.5 a) and a spray ball was positioned in the middle of the bowl (Fig.5 b). The spray ball can supply a water flow rate of 18 l/min with 360 ° of rotation and it provides the mechanical action necessary to remove the dirt.

Figure 5: Load configuration

Cycle 2: Phases, Results and Discussion

In this step, a washing cycle composed of three different phases was performed (*):

  • steam injection at 85-90°C for 10 minutes
  • rinse with hot water (75-80°C) for 10 minutes
  • rinse with water (50°C) for 2 minutes

After performing the second phase of the cycle (washing with hot water), some collagen traces were found in the inner surface of the bowl (Fig. 6). For this reason, a third phase was manually added based on the results of the visual inspection.

Figure 6: Bowl after steam injection and rinse with hot water; remaining traces of gelatin are highlighted.

According to literature, the exposure at temperatures higher than 45° hydrolyzes collagen fibers in small peptides and denatures the molecule into gelatin. (Eastoe, 1955; Milles et Bailey, 1999; Bozeac et Odlyha, 2006).

When the sample of this study was subjected to high temperature, a change of dirt consistency from a dry and sticky substance to gelatin was noticed. The degradation of collagen fibers causes the transformation of the substance into a slimy matter, which is easier remove then in its initial condition.

A third phase was added to the washing cycle in order enhance mechanical action to remove every residual.

With an additional rinse (water at 50°C), the cycle proved to be more efficient, so at the end of this phase, the bowl resulted completely clean (see Fig. 7).

Figure 7: Bowl at the end of cycle 2

Third Session of Trials: General Information and Load Configuration

A repeated cycle was carried out to confirm the previous result. The collagen provided by the customer (1:1 mixture with water) was applied to the inner surface of the bowl and after 24h, when collagen dried, the third washing cycle was run (see Fig. 8).

Figure 8: Bowl dirtied with collagen

The bowl was located into the Washer with 15°C of inclination. In the middle of the bowl the spray ball was placed (see Fig. 9).

Figure 9: Load configuration

Cycle 3: Phases, Results and Discussion

A final washing cycle with the following phases was tested:

  • steam injection at 85-90°C for 10 minutes
  • washing with hot water (73-75°C) for 5 minutes (for two times)
  • rinse with water and compressed air for 2 minutes (*)

The washing phase was divided in two steps of 5 minutes each, with a few seconds interval,  allowing the gelatin to drop down.

At the end of this stage, a rinse with compressed air mixed with water provided an effective removing of the gelatin (Fig. 10).

Figure 10: Bowl after cycle 3

Final Considerations

In this study, an optimal washing cycle has been designed to effectively remove collagen from a stainless-steel bowl surface. The approach used was based in the application of two different “cleaning media”:

  • Steam, which has proven to soften dried collagen;
  • Water and air, which provided the mechanical action needed for effective collagen

After three different trials, the use of steam in softening the residues of collagen can be considered optimal to support the mechanical action of air and water. This combined approach has demonstrated to provide a complete cleaning of metal bowls after visual inspection.

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