Spray drying of probiotics and other food-grade bacteria: A review
TL;DR: This review highlights some key strategies to improve the viability and efficacy of probiotics spray-drying, such as the enhancement of bacterial resistance, improved protection of the drying medium and optimization ofThe drying process.
Abstract: Background Probiotic and starter bacteria are generally dried to produce easy-to-use ingredients that are stable and flexible for applications in the food, feed and pharmaceutical industry. The overall demand for dried probiotic bacteria has increased in the context of a rapidly growing market, evidencing the need for their larger scale production. Scope and approach The spray-drying of bacteria enables a larger production scale than the freeze-drying currently used; energy costs are lower and the process is sustainable. This is also a promising way to microencapsulate bacteria within various protective matrices to ensure their improved resistance during storage, technological processes and digestive stresses. Key findings and conclusions This review highlights some key strategies to improve the viability and efficacy of probiotics spray-drying, such as the enhancement of bacterial resistance, improved protection of the drying medium and optimization of the drying process. It also focuses on factors during the pre- and post-drying stages which may influence the quality and efficacy of spray-dried probiotic powders.
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TL;DR: These properties suggest that postbiotics may contribute, to the improvement of host health by improving specific physiological functions, even though the exact mechanisms have not been entirely elucidated.
Abstract: Background It has been recognized that a number of mechanisms mediating the health benefits of beneficial bacterial cells do require viability. However, new terms such as paraprobiotic or postbiotic have emerged to denote that non-viable microbial cells, microbial fractions, or cell lysates might also offer physiological benefits to the host by providing additional bioactivity. Scope and approach This review provides an overview of the postbiotic concept, evidence of their health benefits and possible signaling pathways involved in their protective effects, as well as perspectives for applications in foods and pharmaceuticals. Key findings and conclusions Postbiotics refers to soluble factors (products or metabolic byproducts), secreted by live bacteria, or released after bacterial lysis, such as enzymes, peptides, teichoic acids, peptidoglycan-derived muropeptides, polysaccharides, cell surface proteins, and organic acids. These postbiotics have drawn attention because of their clear chemical structure, safety dose parameters, long shelf life and the content of various signaling molecules which may have anti-inflammatory, immunomodulatory, anti-obesogenic, antihypertensive, hypocholesterolemic, anti-proliferative, and antioxidant activities. These properties suggest that postbiotics may contribute, to the improvement of host health by improving specific physiological functions, even though the exact mechanisms have not been entirely elucidated.
429 citations
Journal Article•
TL;DR: Probiotic milk‐based formulations were spray‐dried with various combinations of prebiotic substances in an effort to generate synbiotic powder products.
Abstract: AIMS Probiotic milk-based formulations were spray-dried with various combinations of prebiotic substances in an effort to generate synbiotic powder products. METHODS AND RESULTS To examine the effect of growth phase and inclusion of a prebiotic substance in the feed media on probiotic viability during spray-drying, Lactobacillus rhamnosus GG was spray-dried in lag, early log and stationary phases of growth in reconstituted skim milk (RSM) (20% w/v) or RSM (10% w/v), polydextrose (PD) (10% w/v) mixture at an outlet temperature of 85-90 degrees C. Stationary phase cultures survived best (31-50%) in both feed media and were the most stable during powder storage at 4-37 degrees C over 8 weeks, with 30-140-fold reductions in cell viability at 37 degrees C in RSM and PD/RSM powders, respectively. Stationary phase Lact. rhamnosus GG was subsequently spray-dried in the presence of the prebiotic inulin in the feed media, composed of RSM (10% w/v) and inulin (10% w/v), and survival following spray-drying was of the order 7.1-43%, while viability losses of 20,000-90,000-fold occurred in these powders after 8 weeks' storage at 37 degrees C. Survival of the Lactobacillus culture after spray-drying in powders produced using PD (20% w/v) or inulin (20% w/v) as the feed media was only 0.011-0.45%. To compare different probiotic lactobacilli during spray-drying, stationary phase Lact. rhamnosus E800 and Lact. salivarius UCC 500 were spray-dried using the same parameters as for Lact. rhamnosus GG in either RSM (20% w/v) or RSM (10% w/v) and PD (10% w/v). Lact. rhamnosus E800 experienced approx. 25-41% survival, yielding powders containing approximately 10(9) CFU g(-1), while Lact. salivarius UCC 500 performed poorly, experiencing over 99% loss in viability during spray-drying in both feed media. In addition to the superior survival of Lact. rhamnosus GG after spray-drying, both strains experienced higher viability losses (570-700-fold) during storage at 37 degrees C over 8 weeks compared with Lact. rhamnosus GG. CONCLUSIONS Stationary phase cultures were most suitable for the spray-drying process, while lag phase was most susceptible. The presence of the prebiotics PD and inulin did not enhance viability during spray-drying or powder storage. SIGNIFICANCE AND IMPACT OF THE STUDY High viability (approximately 10(9) CFU g(-1)) powders containing probiotic lactobacilli in combination with prebiotics were developed, which may be useful as functional food ingredients for the manufacture of probiotic foods.
348 citations
TL;DR: In this paper, a spray-dried mixture of inulin, hi-maize, and trehalose was used to encapsulate Lactobacillus acidophilus La-5.
Abstract: Microparticles containing inulin, hi-maize, and trehalose were produced through spray drying to encapsulate Lactobacillus acidophilus La-5. Afterwards, the encapsulation efficiency, thermal resistance, gastrointestinal simulation, storage stability, and the microparticles’ size and morphology were analyzed to evaluate the protective effect against the thermal conditions of the spray dryer of the different encapsulating matrices. Inulin and hi-maize encapsulating matrices showed the greatest encapsulation efficiency of 93.12% and 94.26%, respectively. Concerning thermal resistance, the trehalose encapsulating matrix provided the greatest protection for this microorganism. The microparticles produced with hi-maize showed the greatest viability in simulated gastrointestinal conditions thus providing higher protection for Lactobacillus acidophilus La-5. Regarding storage stability, microparticles containing trehalose showed the fewest viability losses during 120 days of storage. However, notably, at the end of 120 days of storage at room temperature (25 °C), microparticles containing inulin, hi-maize, and trehalose all kept their counts above the recommended level (>6 log CFU/g−1). Concerning the physical characteristics of the microparticles, particle sizes were as expected for products obtained by spray drying. Scanning electron microscopy showed no ruptures or cracks on the surfaces of the microparticles, a desirable characteristic for high protection.
95 citations
TL;DR: Albeit current results are promising for microparticles and nanomaterials, more research is needed to evaluate the application of various natural ingredients in meat processing.
Abstract: Background Meat has a complex physical structure and chemical composition that is very prone to oxidation. Plants are sources of biologically active compounds (antioxidants) of interest as potential raw materials for meat processing, primary as replacements for synthetic additives. Some examples are essential oils from aromatic plants that are usually unstable under common processing and storage conditions and exhibit strong smell and off flavour. Hence, stable delivery systems like encapsulation are required. Scope and approach Encapsulation, and particularly spray-drying, offers protection of active compounds, their controlled and targeted release in food products and ability to mask unacceptable odours in products. Key findings and conclusions Albeit current results are promising for microparticles and nanomaterials, more research is needed to evaluate the application of various natural ingredients in meat processing. Direction of future research should address functionality of systems, consumers’ health concerns and benefits, better sensory acceptance, reduced operating costs, scalability for industrial needs, and size of environmental footprints.
85 citations
Journal Article•
TL;DR: In this article, a self-priming peristaltic pump draws the liquid from the sample container and drives it through a small diameter jet into the main chamber, at the same time, an integral compressor pumps air into the outer tube of the jet which, due to the close proximity of the air outlet to the liquid jet, causes the liquid to emerge to a fine, atomized spray.
Abstract: This system features spray drying in an inert gas atmosphere where nitrogen circulates in a closed loop within the spray dryer. It must be used for the spray drying of spray samples containing organic solvents or where the product must not contact oxygen during drying.Closed loop systems are gas and powder tight and are designed to the strictest safety standards to prevent external discharge when using organic solvent based spray samA self-priming peristaltic pump draws the liquid from the sample container and drives it through a small diameter jet into the main chamber. At the same time, an integral compressor pumps air into the outer tube of the jet which, due to the close proximity of the air outlet to the liquid jet, causes the liquid to emerge to a fine, atomized spray. Hot air is blown through the main chamber evaporating the liquid content of the spray and leaving the solid particles of the material, which are normally in a free flowing state, to be separated from the exhaust air flow by a cyclone and collected in the sample collector container. Micro-encapsulation Encapsulation technique is also used with spray drying by the food, feed, pharma and other industries. A substance to be encapsulated (the load) and an amphipathic carrier e.g. starch, dextrin or other modified starch, etc. are homogenized as a suspension in water slurry. The slurry is then fed into a spray dryer where the carrier forms a hardened shell around the load. The sprayed particle with its active compound is thus embedded and protected with the carrier shell.
84 citations
References
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TL;DR: An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics and the appropriate use and scope of the term probiotic.
Abstract: An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics. It is now 13 years since the definition of probiotics and 12 years after guidelines were published for regulators, scientists and industry by the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO). The FAO/WHO definition of a probiotic--"live microorganisms which when administered in adequate amounts confer a health benefit on the host"--was reinforced as relevant and sufficiently accommodating for current and anticipated applications. However, inconsistencies between the FAO/WHO Expert Consultation Report and the FAO/WHO Guidelines were clarified to take into account advances in science and applications. A more precise use of the term 'probiotic' will be useful to guide clinicians and consumers in differentiating the diverse products on the market. This document represents the conclusions of the ISAPP consensus meeting on the appropriate use and scope of the term probiotic.
5,114 citations
TL;DR: The goal of this Consensus Statement is to engender appropriate use of the term 'prebiotic' by relevant stakeholders so that consistency and clarity can be achieved in research reports, product marketing and regulatory oversight of the category.
Abstract: With the continued interest in the role of the gut microbiota in health, attention has now turned to how to harness the microbiota for the benefit of the host. This Consensus Statement outlines the definition and scope of the term 'prebiotic' as determined by an expert panel convened by the International Scientific Association for Probiotics and Prebiotics in December 2016. In December 2016, a panel of experts in microbiology, nutrition and clinical research was convened by the International Scientific Association for Probiotics and Prebiotics to review the definition and scope of prebiotics. Consistent with the original embodiment of prebiotics, but aware of the latest scientific and clinical developments, the panel updated the definition of a prebiotic: a substrate that is selectively utilized by host microorganisms conferring a health benefit. This definition expands the concept of prebiotics to possibly include non-carbohydrate substances, applications to body sites other than the gastrointestinal tract, and diverse categories other than food. The requirement for selective microbiota-mediated mechanisms was retained. Beneficial health effects must be documented for a substance to be considered a prebiotic. The consensus definition applies also to prebiotics for use by animals, in which microbiota-focused strategies to maintain health and prevent disease is as relevant as for humans. Ultimately, the goal of this Consensus Statement is to engender appropriate use of the term 'prebiotic' by relevant stakeholders so that consistency and clarity can be achieved in research reports, product marketing and regulatory oversight of the category. To this end, we have reviewed several aspects of prebiotic science including its development, health benefits and legislation.
2,863 citations
"Spray drying of probiotics and othe..." refers background in this paper
...As concluded by Morgan, Herman, White and 180 Vesey (2006), this result suggests that either bact eri do not need to synthesize new 181 proteins during recovery from drying injury, or tha these injured bacteria are unable 182 to synthesize proteins....
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...Encapsulated bacterial ce lls have been widely reported as 656 being more stable than free cells (De Prisco & Maur iello, 2016). Song, Cho and Park 657 (2003) showed that the protective effect of encapsu lation during storage increased as 658...
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...Journal of Food 1145 Engineering, 193, 10–19. https://doi.org/10.1016/j.jfoodeng.2016.08.0 1146 Hill, C., Guarner, F., Reid, G., Gibson, G. R., Merenstein, D. J., Pot, B., … Sanders, 1147 M. E. (2014)....
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TL;DR: Results obtained with infrared spectroscopy indicate that trehalose and DPPC interact by hydrogen bonding between the OH groups in the carbohydrate and the polar head groups of DPPC, and this interaction is specific totrehalose.
Abstract: Trehalose is a nonreducing disaccharide of glucose commonly found at high concentrations in anhydrobiotic organisms. In the presence of trehalose, dry dipalmitoyl phosphatidylcholine (DPPC) had a transition temperature similar to that of the fully hydrated lipid, whereas DPPC dried without trehalose had a transition temperature about 30 degrees Kelvin higher. Results obtained with infrared spectroscopy indicate that trehalose and DPPC interact by hydrogen bonding between the OH groups in the carbohydrate and the polar head groups of DPPC. These and previous results show that this hydrogen bonding alters the spacing of the polar head groups and may thereby decrease van der Waals interactions in the hydrocarbon chains of the DPPC. This interaction between trehalose and DPPC is specific to trehalose. Hence this specificity may be an important factor in the ability of this molecule to stabilize dry membranes in anhydrobiotic organisms.
1,396 citations
Additional excerpts
...…stabilizing effect of trehalose on 339 membranes and proteins, by replacing the water around polar residues within these 340 macromolecular structures (i.e. water replacement hypot esis), and thus decreasing 341 the membrane phase transition temperature (Crowe et al., 1984; Morgan et al., 2006)....
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TL;DR: Evidence is presented here showing that trehalose has a remarkably high glass-transition temperature (Tg), which makes this sugar useful in stabilization of biomolecules of use in human welfare and may explain the stability and longevity of anhydrobiotes that contain it.
Abstract: Numerous organisms are capable of surviving more or less complete dehydration. A common feature in their biochemistry is that they accumulate large amounts of disaccharides, the most common of which are sucrose and trehalose. Over the past 20 years, we have provided evidence that these sugars stabilize membranes and proteins in the dry state, most likely by hydrogen bonding to polar residues in the dry macromolecular assemblages. This direct interaction results in maintenance of dry proteins and membranes in a physical state similar to that seen in the presence of excess water. An alternative viewpoint has been proposed, based on the fact that both sucrose and trehalose form glasses in the dry state. It has been suggested that glass formation (vitrification) is in itself sufficient to stabilize dry biomaterials. In this review we present evidence that, although vitrification is indeed required, it is not in itself sufficient. Instead, both direct interaction and vitrification are required. Special properties have often been claimed for trehalose in this regard. In fact, trehalose has been shown by many workers to be remarkably (and sometimes uniquely) effective in stabilizing dry or frozen biomolecules, cells, and tissues. Others have not observed any such special properties. We review evidence here showing that trehalose has a remarkably high glass-transition temperature (Tg). It is not anomalous in this regard because it lies at the end of a continuum of sugars with increasing Tg. However, it is unusual in that addition of small amounts of water does not depress Tg, as in other sugars. Instead, a dihydrate crystal of trehalose forms, thereby shielding the remaining glassy trehalose from effects of the added water. Thus under less than ideal conditions such as high humidity and temperature, trehalose does indeed have special properties, which may explain the stability and longevity of anhydrobiotes that contain it. Further, it makes this sugar useful in stabilization of biomolecules of use in human welfare.
1,276 citations
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...This results in the phospholipid chains gaining a rigid and fully 283 extended structure (Leslie et al., 1995; Crowe et al., 1998)....
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TL;DR: Increased survival is attributed to the sugars' ability to lower the membrane phase transition temperature and to protect protein structure in the dry state and the role of membrane phase transitions in the survival of the organisms during drying and rehydration.
Abstract: The microorganisms Escherichia coli DH5 alpha and Bacillus thuringiensis HD-1 show an increased tolerance to freeze-drying when dried in the presence of the disaccharides trehalose and sucrose. When the bacteria were dried with 100 mM trehalose, 70% of the E. coli and 57% of the B. thuringiensis organisms survived, compared with 56 and 44%, respectively, when they were dried with sucrose. Only 8% of the E. coli and 14% of the B. thuringiensis organisms survived drying without the sugars. Fourier transform infrared spectroscopy was used to investigate the role of membrane phase transitions in the survival of the organisms during drying and rehydration. Both E. coli and B. thuringiensis showed an increase of 30 to 40 degrees C in the temperature of their phospholipid phase transition when dried without the sugars, while phase transition temperatures of those dried with the sugars remained near those of the hydrated cells. A Fourier transform infrared spectroscopy microscope made it possible to investigate the effects of drying on the protein structure in the intact cells. The amide II peak shifts from 1,543 cm-1 in the hydrated cells to about 1,533 cm-1 in the cells dried without sugar. There is no shift in the amide II peak when the cells are dried with trehalose or sucrose. We attribute the increased survival to the sugars9 ability to lower the membrane phase transition temperature and to protect protein structure in the dry state.(ABSTRACT TRUNCATED AT 250 WORDS)
988 citations
Additional excerpts
...This results in the phospholipid chains gaining a rigid and fully 283 extended structure (Leslie et al., 1995; Crowe et al., 1998)....
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