Spray drying for the retention of food bioactive compounds and nutraceuticals – 150th anniversary of spray drying

Abstract

Since the early invention by Samuel Percy in 1872, spray drying has become one of the most convenient means to produce powders from liquid materials during a simple and continuous operation. Spray drying is widely used in food, pharmaceutical, biotechnology and chemical industries to produce instant powders, beverages, microencapsulated extracts, oils and drugs or biotechnological preparations. Although this drying method is usually perceived as very intensive/high-temperature drying, the temperature of material during drying remains at a medium level, due to so-called cooling effect of evaporation. This fact, in combination with a very short contact time, makes it possible to dry thermolabile products with limited degradation. However, drying parameters have to be carefully adjusted to each individual material to reduce degradation and enhance quality of a final product. Due to the aforementioned advantages, the popularity of spray drying as a method for preservation, pulverization and microencapsulation is increasing. During 2000–2010, the number of articles shown by Google Scholar database as search result for “spray drying food applications” was 17,100, while during the next decade (2010–2020), such number was more than twice larger, reaching 36,400. We are releasing this Special Issue a few months before the start of 2022, in which we will celebrate 150th anniversary of the invention of this unique drying operation, to show the current trends and achievements in this topic. This Special Issue includes high-quality review and original research articles, covering recent advancements on spray drying of food and related materials, including sugar-rich materials, fruit pulp, plant extracts, oils and active compounds. The authors who have contributed to these high-quality articles are internationally well-known experts in their fields. Among food materials which can be produced in the powdery form by spray drying, a group of materials that contain high sugars contents (e.g., fruit pulps, juices, concentrates) is the most challenging. There is still need to find a method that allows reduced used of carriers (drying aids) to reduce stickiness during drying, or to replace conventional carriers by novel green materials. The challenges in drying such products and approaches recently applied are presented in the first review article, opening the Special Issue. The second large group of materials, which are increasingly subject to spray drying is plant extracts and essential oils, which are microencapsulated via spray drying to simultaneously be stabilized and be converted in a powdery form. The second article of the issue is dedicated to reviewing spray drying applied as a microencapsulation method of food bioactive components. A novel approach to replace conventional atomizers by ultrasonic atomizer in spray drying is presented as the third review article. Articles 4-10 present the results connected with the impact of spray drying on retention and stability of different biocompounds: phenolics, 5-caffeoylquinic acid, essential oils from different plants, carotenoids in paprika oleoresin and anthocyanins in pomegranate juice. The important topic included in these papers is the substitution of conventional wall materials by novel green carriers, in line with the current trend. Such novel carriers include hydrolyzed collagen, chitosan, microcrystalline cellulose, inulin or cellulose nanofibrils extracted from fibrous ginger residues. Article 11, closing the Special Issue, is related to pharmaceutical application. Spray drying has revealed in this case to be an ideal method for the production of starch-paracetamol complexes with tailor-made functional properties. As the Guest Editors, we sincerely thank the authors for their valuable contributions, especially during the current uncertain times. We are happy to be able to bring this Special Issue to our valued readers. Let’s start the celebration of 150th anniversary of spray drying!