Effect of Process Parameters, Protectants and Carrier Materials on the Survival of Yeast Cells during Fluidized Bed Granulation for Tableting

Does tablet shape and height influence survival of fluidized bed-granulated living microorganisms during compaction?

The provision of effective probiotic formulations requires gentle processing to maintain the viability of the probiotic microorganisms, which is essential for their health-promoting effects. The drying of microorganisms by fluidized bed spray granulation and subsequent processing of the granules into tablets has proven to be a promising process route in previous studies of the same authors. In these, the influence of various factors was considered using cylindrical tablets with a diameter of 11.28 mm and a mass of 450 mg. These flat tablets are unpleasant to ingest and other tablet geometries should be considered for administration of probiotics but to date, no studies exist on the influence of geometric factors of the tableting tool and of the tablets on the survival of microorganisms. To address this aspect, the survival of Saccharomyces cerevisiae during the production of flat, round tablets with different tablet masses and thus heights as well as differently shaped convex tablets is determined and related to the physical-mechanical tablet properties to derive process-structure-property relationships. It turned out that higher tablet heights were advantageous regarding microbial survival and mechanical strength which is attributed to a lower elastic recovery. However, the use of differently shaped tools had a smaller influence on microbiological and mechanical tablet properties since the global tablet porosity was hardly affected.

Fermentation of American elderberry juice yields functional phytochemicals for spray dried protein-polyphenol ingredients

American elderberry juice (EBJ) and fermented elderberry juice (EBF) were spray dried using two different carriers: S. cerevisiae yeast (SC), used for juice fermentation and as encapsulating agent, and pea protein, to produce protein-polyphenol ingredients. The spray drying (SD) performance (solids recovery, SR; phenolic retention, PR) and quality attributes (physicochemical and functional properties, phytochemical content and bioaccessibility after in vitro digestion) of eight treatments of spray dried elderberry particles were determined. The total phenolic content (TPC) of EBJ (4476 ± 169 mg GAE/L) increased by 27 % after fermentation (EBF: 5706 ± 199 mg GAE/L). The SD performance of EBF (SR > 50 %; PR 55.7-63.9 %) was significantly higher (p < 0.05) compared to EBJ (SR < 50 %; PR 28.6-42.8 %). Stable (aw < 0.3) protein-polyphenol particles, with pH-dependent solubility that increased as pH went from 4 to 10, were produced. The TPC of EBF-derived particles (26.2-28.7 mg GAE/g) was 22-31 % higher than EBJ-derived particles (20.4-21.9 mg GAE/g) and anthocyanins were the major phenolic group detected. An increase in nearly all phenolic metabolite concentrations was observed after fermentation, and an additional increment was observed after spray drying. Phenolic bioaccessibility improved (17-25 % higher) after S. cerevisiae fermentation and when using SC as the drying carrier compared to phenolics source (EBJ or EBF). Overall, here we show a sensible strategy to produce protein-polyphenol particles with better SD performance and enhanced phytochemical content and profile. Our fermentation and spray drying strategy provides practical and efficient means to produce functional fruit ingredients for the emerging clean-label, health-oriented market.

Recent Advances in the Understanding of Stress Resistance Mechanisms in Probiotics: Relevance for the Design of Functional Food Systems

In recent years, more and more scientific community, food producers, and food industry show increased interest in functional foods containing probiotics, which is a big challenge. The consumption of probiotics in the context of a balanced diet through the consumption of functional foods or through the intake of pharmaceutical preparations has proven to contribute to the improvement of human health, even contributing to the prevention of diseases. In order for probiotics to be considered suitable for consumption, they must contain a minimum concentration of viable cells, namely, at least 107 colony forming units of beneficial microbes per gram. Ensuring the viability of bacterial cells until the moment of consumption is the overriding priority of functional probiotic food manufacturers. Probiotic bacteria are subject to stress conditions not only during food manufacturing but also during gastrointestinal passage, which limit or even compromise their functionality. This paper first examines all the stressful conditions faced by probiotic cells in their production stages and related to the conditions present in the bioreactor fermentation and drying processes as well as factors related to the food matrix and storage. The stress situations faced by probiotic microorganisms during the gastrointestinal transit especially during stomach and intestinal residence are also analyzed. In order to understand the adaptation mechanisms of probiotic bacteria to gastrointestinal stress, intrinsic and adaptive mechanisms identified in probiotic strains in response to acid stress and to bile and bile acid stress are analyzed. In addition, improvement strategies for multiple stress tolerance of lactic acid bacteria through directions dealing with stress, accumulation of metabolites, use of protectants, and regulation of technological parameters are examined. Finally, the definition of postbiotics, inanimate microorganisms and/or their components conferring health benefits, is also introduced. Postbiotics include cell lysates, enzymes, and cell wall fragments derived from probiotic bacteria and may represent an alternative to the use of probiotics, when they do not tolerate stressful conditions.

Optimization of Medium Composition and Fluidized Bed Drying Conditions for Efficient Production of Dry Yeast

Yeast formulations such as dry yeast are essential for supplying microbial starters to the alcoholic beverage industry. In Korea, the expensive freeze-drying method is used to manufacture brewer's dry yeast, and therefore an economical process such as fluidized bed drying is needed. In the dry yeast manufacturing process, the medium and drying conditions are key factors that determine its quality and manufacturing cost. In this study, we aimed to optimize the medium composition and fluidized bed drying conditions for the efficient production of dry yeast. Muscovado and corn steep liquor were used as the carbon and nitrogen sources, respectively, and their optimal concentrations were identified using response surface methodology for efficient cultivation of Saccharomyces cerevisiae ReY4-7 isolated from nuruk. Central composite design analysis revealed that the optimal medium composition was 146.12 g/L muscovado and 58.68 g/L corn steep liquor. A dry cell weight of 36 g/L was achieved during 24 h of batch fermentation in a 30-L bioreactor containing this medium. Analysis of protective agents against fluidized bed drying revealed Span 80 as the strongest protective agent for S. cerevisiae ReY4-7. Response surface methodology revealed 50 °C and 41.45 min as the optimal fluidized bed drying conditions, under which the viable cell count reached 10.28 log CFU/g, comparable to that of the commercial dry yeast products. Overall, optimization of the medium and drying conditions significantly improved the final cell concentration in the cultivation process and the viable cell count in the drying process of dry yeast.

Influence of multiple compression phases during tableting of spray dried Saccharomyces cerevisiae on microbial survival and physical-mechanical tablet properties

The viability of probiotic microorganisms is essential for their health-promoting effects and must be preserved in the best possible way during the production of the final dosage form, such as tablets. This applies to both drying and tableting. Saccharomyces cerevisiae is spray-dried with suitable protective additives, which were identified in a previous study in which also the influence of the formulation during tableting was investigated. One aspect that has not yet been addressed is the effect of multiple compression, as it is typical with pre- and main compression when using rotary tablet presses. To investigate this, tablets are compressed up to five times. It is shown that when tablet strength and survival are considered together, the application of a pre- and main pressure does not have a significant effect. This facilitates the transferability of findings of compaction studies with a single compression phase. In addition, the data allow to consolidate the mechanism of inactivation of microorganisms during tableting found in previous studies by the same authors. This is based on the porosity reduction, whereby it is shown in the present study that it is irrelevant how this reduction is achieved (change in compression stress or the number of compression cycles).

Beer wheat residue as a probiotic carrier: physicochemical properties via fluid bed granulation (Beer wheat residue for lactic acid bacteria encapsulation)

BACKGROUND

In recent years, consumer preference for symbiotics containing live bacteria has surged, driven by the acknowledged health benefits. Wheat residue from beer brewing, rich in dietary fiber, remains an unexplored prebiotic raw material for developing vegan probiotic powdered products. Concerns about ambient conditions, dehydration and drying affecting bacterial cell viability prompt the investigation of protective agents (maltodextrin, l-arabinose, casein, whey protein, skimmed milk) and fluidized bed granulation microencapsulation for enhancing the survival rate of Lactiplantibacillus plantarum NKUST 817.

RESULTS

The results of the study show that wheat residue, when utilized as the carrier with 10% indigestible dextrin FB06, served as the optimal protective agent. Optimal air inlet temperature (45, 55 and 65 °C) for fluidized bed granulation was investigated along with cell survival rate and probiotic powder characteristics such as moisture, water activity, hygroscopicity, solubility, bulk density and flowability. Bacteria without protective agents showed a survival rate of only 82.63-86.96%. However, the addition of 10% indigestible dextrin FB06 significantly increased in the survival rate of bacteria (granulated at 45-65 °C) to 93.52-95.18%. The microencapsulated bacteria powder exhibited low moisture (2.38-4.36%) and water activity (0.06-0.22). Powder fluidity, indicated by Carr's index (10.87-13.62) and the Hausner ratio (1.13-1.16%), demonstrated good flowability. Furthermore, the powder remained stable for 45 days, with a viable bacteria count of 7.29 log colony-forming units g-1 and a survival rate of 88.69%.

CONCLUSION

This study pioneers vegan probiotic product development at the same time as addressing processing challenges to optimize strain resilience. This research stablishes wheat residue as a suitable candidate for a probiotics carrier. © 2024 Society of Chemical Industry.

The Increase in the Plasticity of Microcrystalline Cellulose Spheres' When Loaded with a Plasticizer

Compaction pressure can induce an undesirable solid-state polymorphic transition in drugs, fragmentation, loss of coated pellet integrity, and the decreased viability and vitality of microorganisms. Thus, the excipients with increased plasticity can be considered as an option to decrease the undesirable effects of compaction pressure. This study aims to increase the plasticity (to reduce the mean yield pressure; Py) of dried microcrystalline cellulose (MCC) by loading it with a specially selected plasticizer. Diethyl citrate (DEC), water, and glycerol were the considered plasticizers. Computation of solubility parameters was used to predict the miscibility of MCC with plasticizers (possible plasticization effect). Plasticizer-loaded MCC spheres with 5.0 wt.% of water, 5.2 wt.% of DEC, and 4.2 wt.% glycerol were obtained via the solvent method, followed by solvent evaporation. Plasticizer-loaded formulations were characterised by TGA, DSC, pXRD, FTIR, pressure-displacement profiles, and in-die Heckel plots. Py was derived from the in-die Heckel analysis and was used as a plasticity parameter. In comparison with non-plasticized MCC (Py = 136.5 MPa), the plasticity of plasticizer-loaded formulations increased (and Py decreased) from DEC (124.7 MPa) to water (106.6 MPa) and glycerol (99.9 MPa), and that was in full accordance with the predicted miscibility likeliness order based on solubility parameters. Therefore, water and glycerol were able to decrease the Py of non-plasticized MCC spheres by 16.3 and 30.0%, respectively. This feasibility study showed the possibility of modifying the plasticity of MCC by loading it with a specially selected plasticizer.

Mining association rules between the granulation feasibility and physicochemical properties of aqueous extracts from Chinese herbal medicine in fluidized bed granulation

Fluidized bed granulation (FBG) is a widely used granulation technology in the pharmaceutical industry. However, defluidization caused by the formation of large aggregates poses a challenge to FBG, particularly in traditional Chinese medicine (TCM) due to its complex physicochemical properties of aqueous extracts. Therefore, this study aims to identify the complex relationships between physicochemical characteristics and defluidization using data mining methods. Initially, 50 types of TCM were decocted and assessed for their potential influence on defluidization using a set of 11 physical properties and 10 chemical components, utilizing the loss rate as an evaluation index. Subsequently, the random forest (RF) and Apriori algorithms were utilized to uncover intricate association rules among physicochemical characteristics and defluidization. The RF algorithm analysis revealed the top 8 critical factors associated with defluidization. These factors include physical properties like glass transition temperature (Tg) and dynamic surface tension (DST) of DST100ms, DST1000ms, DST10ms and conductivity, in addition to chemical components such as fructose, glucose and protein contents. The results from Apriori algorithm demonstrated that lower Tg and conductivity were associated with an increased risk of defluidization, resulting in a higher loss rate. Moreover, DST100ms, DST1000ms and DST10ms exhibited a contrasting trend in the physical properties Specifically, defluidization probability increases when Tg and conductivity dip below 29.04℃ and 6.21 ms/m respectively, coupled with DST10ms, DST100ms and DST1000ms values exceeding 70.40 mN/m, 66.66 mN/m and 61.58 mN/m, respectively. Moreover, an elevated content of low molecular weight saccharides was associated with a higher occurrence of defluidization, accompanied by an increased loss rate. In contrast, protein content displayed an opposite trend regarding chemical properties. Precisely, the defluidization likelihood amplifies when fructose and glucose contents surpass 20.35 mg/g and 34.05 mg/g respectively, and protein concentration is less than 1.63 mg/g. Finally, evaluation criteria for defluidization were proposed based on these results, which could be used to avoid this situation during the granulation process. This study demonstrated that the RF and Apriori algorithms are effective data mining methods capable of uncovering key factors affecting defluidization.

Process and formulation parameters influencing the survival of Saccharomyces cerevisiae during spray drying and tableting

Probiotic microorganisms provide health benefits to the patient when administered in a viable form and in sufficient doses. To ensure this, dry dosage forms are preferred, with tablets in particular being favored due to several advantages. However, the microorganisms must first be dried as gently as possible. Here, the model organism Saccharomyces cerevisiae was dried by spray drying. Various additives were tested for their ability to improve yeast cell survival during drying. In addition, the influence of various process parameters such as inlet temperature, outlet temperature, spray rate, spray pressure and nozzle diameter was investigated. It was possible to dry the yeast cells in such a way that a substantial proportion of living microorganisms was recovered after reconstitution. Systematic variation of formulation and process parameters showed that the use of protective additives is essential and that the outlet temperature determines the survival rate. The subsequent compression of the spray-dried yeast reduced viability and survival could hardly be improved by the addition of excipients, but the tabletability of spray-dried yeast protectant particles was quite good. For the first time, loss of viability during compaction of spray-dried microorganisms was correlated with the specific densification, allowing a deeper understanding of the mechanism of cell inactivation during tableting.