Mitigating any safety concerns and providing Hazard Analysis Critical Control Point (HACCP) knowledge for optimal UAE practice in the medicinal mushroom industry


Ultrasonic-Assisted Extraction (UAE) processing has attracted growing interest in the field of food science and technology. In general, significant positive results have been reported for the use of UAE in a variety of applications, especially for the improvement of ‘mass transfer’, which is the fundamental mechanism of any extraction method (Knorr et al. 2011). In this blog, we hope to ease any concerns regarding the use of UAE. 

We address two discussion points raised by Majid et al. (2015), who conducted a solid review paper on UAE titled ‘Ultrasonication and food technology: A review’. In this review, the authors noted two arguable disadvantages of technology’: 1) the potential chemical changes resulting from UAE i.e the potential formation of radicals and 2) the potential of resistance caused by UAE to reduce mass transfer during extraction.


The conditions in which chemical changes might occur in UAE and how this is mitigated in the production line of Nordic Mushrooms 

As stated in Majid et al. (2015): “Ultrasonication can lead to the formation of radicals as a result of critical temperature and pressure conditions that are responsible for changes in food compounds. The radicals (OH and H) produced in the medium deposit at the surface of cavitation bubbles that stimulate the radical chain reactions which involve formation of degradation products and thus lead to considerable quality defects in product”.

However, in addressing this concern, what Majid et al. (2015) overlooked and failed to note is that this only occurs when high ultrasound frequencies (hundreds of kHz and greater) are applied. According to Czechowska-Biskup et al. (2005), whose paper called ‘Degradation of chitosan and starch by 360-kHz ultrasound’ was cited in Majid et al. (2005)’s discussion on the matter, frequencies between 100–1000 kHz have been reported to degrade constituents. These frequencies are significantly higher than the frequencies generally used in medicinal mushroom extraction via UAE. In fact, most ultrasonication setups that are designed specifically for botanical extraction do not contain ultrasonic probes/sonotrodes operating at such high frequencies.

KÄÄPÄ employs optimally-tuned probe frequencies between 16-40kHz during UAE in the production of the Nordic Mushrooms product line. These frequencies are scientifically proven to optimise bioactive compound yield and extract quality, such as a wider array of compound-molecular weight diversity and branching degree of (1-3; 1-6)-beta-D-glucans (Alzorqi et al. 2016)1. These frequencies have also been shown to deactivate harmful microbes or active enzymes (see figure 1 below). By utilising frequencies below 40kHz and maintaining HACCPs (hazard analysis critical control points) during extraction and production, the Nordic Mushroom production line safely mitigates any risk of unwanted extract constituents, whilst optimising compound of interest (COI) quality and yield.

Figure 1

Figure 1 Use of ultrasonic frequencies in a variety of sonication processes in food science and technology. The red circle reveals the coinciding frequency range of UAE and microorganism inactivation, which is important for quality control (Modified from Knorr et al. 2011).

Although physical and chemical changes occur at every stage of any extraction method utilised (and in any process in life), chemical alteration is not a topic of concern of UAE because at lower frequencies of 20–100 kHz, physical effects dominate. Whereas at higher frequencies such as 200–500 kHz and beyond, chemical effects begin to dominate (Tiwari 2015). 

For more information on the basics of the UAE method in food technology, see the highly-cited research article by Awad et al. (2012) called ‘Applications of ultrasound in analysis, processing and quality control of food: A review’ or feel free to get in touch with our team.


The significance of mass transfer in extraction and how it applies in our production

According to (Esclapez et al. 2011) “frequency of ultrasound waves can impose resistance to mass transfer”, as stated as an issue of UAE in Majid et al. (2015)’s review paper.

Now, according to Esclapez et al. (2011), and as mentioned previously, an extract product’s structure after ultrasonic treatment remains largely unaffected at lower UAE frequencies. Again we reiterate that these lower frequencies are optimally and suitably determined for medicinal mushroom and other botanical extraction methods within the low 16-40kHz frequency range. 

Mass transfer is the fundamental principle of any extraction: 

the transfer of compounds held within the target component (i.e. mushroom fruiting bodies) into the liquid extract solvent (i.e. but not limited to: water, ethanol or glycerin).

In fact, optimising mass transfer is key to optimising extraction, period.

It is correct to say that UAE “imposes resistance” during the extraction process - in the form of acoustic cavitation caused by ultrasonic frequencies. Nevertheless, this resistance is not harming mass transfer. It is in fact optimising desirable extraction mass transfer when “tuned” properly (Vilkhu et al 2008; Awad et al 2012; Tiwari 2015; Medina-Torres et al 2017). 


Hazard Analysis Critical Control Points (HAACPs) for optimal UAE procedures 

To ensure better manufacturing practices regarding the use of UAE in food processing and particularly in medicinal mushroom extract production, it is essential for manufacturers to implement proper Hazard Analysis Critical Control Points (HAACPs) to uphold optimal UAE procedure. 

In Chemat et al. (2011)’s highly-cited review of ultrasonic technology, guidance on HAACPs for UAE operations was presented to enable identification and assessment of the hazards and risks associated with UAE used in production. These exist simply to ensure extraction conditions remain optimal. Table 1 below outlines these critical control points (CCPs) when UAE is operational, showing the associated corrective actions in the right column for each CCP to ensure that undesirable extraction conditions do not occur, mitigating any possible risk of any potential harms within the finer technicalities of UAE.

Table 1

Table 1 Hazard Analysis Critical Control Points (HACCPs) and corrective actions for UAE in practice (adapted from Chemat et al. 2011).

If you would like to get more information on UAE, please contact us.

1 UAE extracts a higher array of polysaccharides, from low to high molecular weight with increased degree of branching, which is of prime importance for the antioxidant bioactivity of (1-3; 1-6)-b-D-glucan polysaccharides (Alzorqi et a.l 2016). 
Polysaccharides are long chains of monosaccharides linked by glycosidic bonds. These chains are usually Branched chains with at least one branch point intermediate between the boundary units [Michel 1996]. The chains differ in structure (for example backbone, sidechains, length) and hence therapeutic function depending on the source material (eg: cereal, yeast, mushroom) and extraction method (eg: conventional or innovative) utilised. 
The enzymes in our gut act on the free ends of the polysaccharides. Having a great deal of branching ensures that our gut enzymes can quickly access the “polysaccharide energy supply” and break the chains down when energy is required.
As controversial data on immunomodulating capacities of high molecular weight β-glucans vs. low molecular weight β-glucans exists (Han et al. 2020), a balance of low-to-high molecular weight polysaccharides ensures optimal extract-consumer benefit.


Key References
Alzorqi, I., & Manickam, S. (2015). Effects of Axial Circulation and Dispersion Geometry on the Scale-Up of Ultrasonic Extraction of Polysaccharides. 00(00), 1–9.
Alzorqi, I., Sudheer, S., Lu, T., & Manickam, S. (2016). Ultrasonics Sonochemistry Ultrasonically extracted b - D -glucan from artificially cultivated mushroom , characteristic properties and antioxidant activity. Ultrasonics - Sonochemistry.
Awad, T. S., Moharram, H. A., Shaltout, O. E., Asker, D., & Youssef, M. M. (2012). Applications of ultrasound in analysis, processing and quality control of food: A review. Food Research International, 48(2), 410–427.
Chemat, F., Abert Vian, M., Fabiano-Tixier, A. S., Nutrizio, M., Režek Jambrak, A., Munekata, P. E. S., Lorenzo, J. M., Barba, F. J., Binello, A., & Cravotto, G. (2020). A review of sustainable and intensified techniques for extraction of food and natural products. Green Chemistry, 22(8), 2325–2353.
Chemat, F., Rombaut, N., Sicaire, A. G., Meullemiestre, A., Fabiano-Tixier, A. S., & Abert-Vian, M. (2017). Ultrasound assisted extraction of food and natural products. Mechanisms, techniques, combinations, protocols and applications. A review. Ultrasonics Sonochemistry, 34, 540–560.
Chemat, F., Zill-E-Huma, & Khan, M. K. (2011). Applications of ultrasound in food technology: Processing, preservation and extraction. Ultrasonics Sonochemistry, 18(4), 813–835.
Cheung, Y. C., & Wu, J. Y. (2013). Kinetic models and process parameters for ultrasound-assisted extraction of water-soluble components and polysaccharides from a medicinal fungus. Biochemical Engineering Journal, 79, 214–220.
Czechowska-Biskup, R., Rokita, B., Lotfy, S., Ulanski, P., & Rosiak, J. M. (2005). Degradation of chitosan and starch by 360-kHz ultrasound. Carbohydrate Polymers, 60(2), 175-184.
Gallo, M., Ferrara, L., & Naviglio, D. (2018). Application of ultrasound in food science and technology: A perspective. Foods, 7(10), 1–18.
Knorr, D., Froehling, A., Jaeger, H., Reineke, K., Schlueter, O., & Schoessler, K. (2011). Emerging technologies in food processing. Annual Review of Food Science and Technology, 2, 203–235.
Majid, I., Nayik, G. A., & Nanda, V. (2015). Ultrasonication and food technology: A review. Cogent Food & Agriculture, 1(1).
Medina-Torres, N., Ayora-Talavera, T., Espinosa-Andrews, H., Sánchez-Contreras, A., & Pacheco, N. (2017). Ultrasound assisted extraction for the recovery of phenolic compounds from vegetable sources. Agronomy, 7(3).
Tiwari, B. K. (2015). Ultrasound: A clean, green extraction technology. TrAC - Trends in Analytical Chemistry, 71, 100–109.
Vilkhu, K., Mawson, R., Simons, L., & Bates, D. (2008). Applications and opportunities for ultrasound assisted extraction in the food industry - A review. Innovative Food Science and Emerging Technologies, 9(2), 161–169.
Wang, Y. C., & Yao, M. C. (2013). Realization of cavitation fields based on the acoustic resonance modes in an immersion-type sonochemical reactor. Ultrasonics Sonochemistry, 20(1), 565–570.
Wu, J.-Y. (2017). Ultrasound-Assisted Extraction of Polysaccharides from Edible and Medicinal Fungi: Major Factors and Process Kinetics. MOJ Food Processing & Technology, 4(2), 48–52.