Cell permeabilization processes for improved encapsulation of oregano essential oil in yeast cells

Sonoprocessing enhances the stabilization of fisetin by encapsulation in Saccharomyces cerevisiae cells

The objective of this study was to investigate for the first time the role of S. cerevisiae natural barriers and endogenous cytoplasmatic bodies on the stabilization of fisetin encapsulated via sonoprocessing coupled to freeze-drying (FD) or spray drying (SD). Both protocols of encapsulation improved the resistance of fisetin against thermal treatments (between 60 and 150 °C) and photochemical-induced deterioration (light exposition for 60 days) compared to non-encapsulated fisetin (antioxidant activity retention of approximately 55% and 90%, respectively). When stored under constant relative humidity (from 32.8 to 90%) for 60 days, yeast carriers improved the half-life time of fisetin by up to 4-fold. Spray dried particles were smaller (4.9 μm) and showed higher fisetin release after simulated gastrointestinal digestion (55.7%) when compared to FD. Freeze-dried particles, in turn, tended to agglomerate more than SD (zeta potential -19.7 mV), resulting in reduced loading features (6.3 mg/g) and less efficient protection of fisetin to heat, photo, and moisture-induced deterioration. Overall, spray-dried sonoprocessed fisetin capsules are an efficient way to preserve fisetin against harsh conditions. Altogether, this report shows that sonoprocessing coupled to drying is an efficient, creative, and straightforward route to protect and deliver lipophilic fisetin using yeast capsules for food applications.

The Valorisation of Melissa officinalis Distillation By-Products for the Production of Polyphenol-Rich Formulations

Lemon balm (Melissa officinalis) is an aromatic and medicinal plant, rich in bioactive ingredients and with superior antioxidant activity. The essential oil of this plant is an expensive product, so the use of the by-products of the essential oil industry is particularly useful. The aim of this research was to process Melissa officinalis distillation by-products to develop a series of polyphenol-rich formulations. In the present research, lemon balm was distilled in a laboratory-scale distiller, and the recovered by-product was used for further successive extractions with acetone and water, using a fixed-bed semi-batch extractor. Acetone extract exhibited relatively poor results as far as yield, phenolic composition and antiradical activity are concerned. However, the aqueous extract presented high yield in both total phenolic content (i.e., 111 mg gallic acid equivalents (GAE)/g, on a dry herb basis (dw)), and anti-radical capacity (205 mg trolox equivalents (TE)/g dw). On a dried extract basis, the results were also impressive, with total phenols reaching 322 mg GAE/g dry extract and antiradical capacity at 593 mg TE/g dry extract. The phenolic components of the extract were identified and quantified by HPLC-DAD. Rosmarinic acid was the major component and amounted to 73.5 mg/g dry extract, while the total identified compounds were quantified at 165.9 mg/g dry extract. Finally, formulations with two different wall materials (gum arabic-maltodextrin and maltodextrin) and two different drying methods (spray-drying and freeze-drying) were applied and evaluated to assess their performance, yield, efficiency and shelf-life of total phenolic content and rosmarinic acid concentration. From the present investigation, it is concluded that after one year of storage, rosmarinic acid does not decrease significantly, while total phenolic content shows a similar decrease for all powders. According to the yield and efficiency of microencapsulation, maltodextrin alone was chosen as the wall material and freeze-drying as the preferred drying method.

Application of Encapsulation Strategies for Probiotics: From Individual Loading to Co-Encapsulation

Consumers are increasingly showing a preference for foods whose nutritional and therapeutic value has been enhanced. Probiotics are live microorganisms, and their existence is associated with a number of positive effects in humans, as there are many and well-documented studies related to gut microbiota balance, the regulation of the immune system, and the maintenance of the intestinal mucosal barrier. Hence, probiotics are widely preferred by consumers, causing an increase in the corresponding food sector. As a consequence of this preference, food industries and those involved in food production are strongly interested in the occurrence of probiotics in food, as they have proven beneficial effects on human health when they exist in appropriate quantities. Encapsulation technology is a promising technique that aims to preserve probiotics by integrating them with other materials in order to ensure and improve their effectiveness. Encapsulated probiotics also show increased stability and survival in various stages related to their processing, storage, and gastrointestinal transit. This review focuses on the applications of encapsulation technology in probiotics in sustainable food production, including controlled release mechanisms and encapsulation techniques.

Encapsulation of wild oregano, Plectranthus amboinicus (Lour.) Spreng, phenolic extract in baker's yeast for the postharvest control of anthracnose in papaya

BACKGROUND

Anthracnose caused by Colletotrichum gloeosporioides is considered as a major postharvest disease affecting many fruits. This plant disease is traditionally managed with synthetic fungicides, which are generally toxic and are linked to pathogen resistance. Recently, microencapsulated bioactives have been developed as potential alternative strategies to these methods, while utilizing natural fungicides and other phytochemicals. Wild oregano, Plectranthus amboinicus (Lour.) Spreng, contains potent antimicrobial phenolics, but these compounds are volatile and relatively unstable, which limits their efficacy during application. Herein, a baker's yeast microencapsulation system was applied to improve the stability of wild oregano phenolic extract (WOPE) and enhance its antifungal activity against anthracnose.

RESULTS

Encapsulation of WOPE in plasmolyzed yeast cells afforded a high encapsulation efficiency (93%) and yielded WOPE-loaded yeast microcapsules (WLYMs) with an average diameter of 2.65 μm. Storage stability studies showed WLYMs are stable for at least 4 months. A 24  -h in vitro release experiment showed that WLYMs had an initial burst release upon redispersion in water, followed by a controlled release to about 80% of the loaded WOPE. Upon application as a spray-type postharvest treatment for papaya, WLYMs exhibited a significantly improved mycelial inhibitory action against C. gloeosporioides and greatly reduced the anthracnose symptoms in papaya fruits.

CONCLUSION

This study presented a yeast microencapsulation system that can effectively stabilize WOPE and enhance its antifungal activity, making this microparticle formulation a promising environmentally safe postharvest treatment option to combat anthracnose symptoms in papaya fruits. © 2022 Society of Chemical Industry.

Ultrasound-assisted encapsulation of curcumin and fisetin into Saccharomyces cerevisiae cells: a multistage batch process protocol

Some of the challenges of yeast encapsulation protocols are low phytochemical internalization rates and limited intracellular compartment of yeasts. This study uses an ultrasound-assisted batch encapsulation (UABE) protocol to optimize the encapsulation of curcumin and fisetin by recovering non-encapsulated biomaterial and further incorporating it into non-loaded yeasts in three encapsulation stages (1ES, 2ES, and 3ES). The effect of selected acoustic energies (166.7 and 333.3 W L^-1 ) on the encapsulation efficiency (EE), yield (EY), and antioxidant activity retention were evaluated, and then, compared with a control process (without ultrasound treatment). Compared to the control, enhanced EEs were achieved for both curcumin (10.9% control to 58.5% UABE) and fisetin (18.6% control to 76.6% UABE) after 3ES and the use of 333.3 W L^-1 . Similarly, the yeast maximum loading capacity was improved from 6.6 to 13.4 mg g^-1 for curcumin; and from 11.1 to 26.4 mg g^-1 for fisetin after UABE protocol. The antioxidant activity of produced biocapsules was positively correlated with the bioactive loaded content of yeasts when ultrasound treatment was applied. Overall, results from this study provide valuable information regarding UABE processes, and moreover, bring new and creative perspectives for the ultrasound technology in the food industry.

Yeast Cells in Microencapsulation. General Features and Controlling Factors of the Encapsulation Process

Besides their best-known uses in the food and fermentation industry, yeasts have also found application as microcapsules. In the encapsulation process, exogenous and most typically hydrophobic compounds diffuse and end up being passively entrapped in the cell body, and can be released upon application of appropriate stimuli. Yeast cells can be employed either living or dead, intact, permeabilized, or even emptied of all their original cytoplasmic contents. The main selling points of this set of encapsulation technologies, which to date has predominantly targeted food and-to a lesser extent-pharmaceutical applications, are the low cost, biodegradability and biocompatibility of the capsules, coupled to their sustainable origin (e.g., spent yeast from brewing). This review aims to provide a broad overview of the different kinds of yeast-based microcapsules and of the main physico-chemical characteristics that control the encapsulation process and its efficiency.

Yeast cells for encapsulation of bioactive compounds in food products: A review

Nowadays bioactive compounds have gained great attention in food and drug industries owing to their health aspects as well as antimicrobial and antioxidant attributes. Nevertheless, their bioavailability, bioactivity, and stability can be affected in different conditions and during storage. In addition, some bioactive compounds have undesirable flavor that restrict their application especially at high dosage in food products. Therefore, food industry needs to find novel techniques to overcome these problems. Microencapsulation is a technique, which can fulfill the mentioned requirements. Also, there are many wall materials for use in encapsulation procedure such as proteins, carbohydrates, lipids, and various kinds of polymers. The utilization of food-grade and safe carriers have attracted great interest for encapsulation of food ingredients. Yeast cells are known as a novel carrier for microencapsulation of bioactive compounds with benefits such as controlled release, protection of core substances without a significant effect on sensory properties of food products. Saccharomyces cerevisiae was abundantly used as a suitable carrier for food ingredients. Whole cells as well as cell particles like cell wall and plasma membrane can act as a wall material in encapsulation process. Compared to other wall materials, yeast cells are biodegradable, have better protection for bioactive compounds and the process of microencapsulation by them is relatively simple. The encapsulation efficiency can be improved by applying some pretreatments of yeast cells. In this article, the potential application of yeast cells as an encapsulating material for encapsulation of bioactive compounds is reviewed.