Short communication
Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids

https://doi.org/10.1016/j.ijfoodmicro.2008.11.001Get rights and content

Abstract

Gastric acidity is the main factor affecting viability of probiotics in the gastrointestinal tract (GIT). This study investigated the survival in simulated gastrointestinal fluids of Bifidobacterium longum Bb-46 encapsulated in interpolymer complexes formed in supercritical carbon dioxide (scCO2). Bacteria were exposed sequentially to simulated gastric fluid (SGF, pH 2) for 2 h and simulated intestinal fluid (SIF, pH 6.8) for 6 or 24 h. Total encapsulated bacteria were determined by suspending 1 g of product in SIF for 6 h at 37 °C prior to plating out. Plates were incubated anaerobically at 37 °C for 72 h. The interpolymer complex displayed pH-responsive release properties, with little to no release in SGF and substantial release in SIF. There was a limited reduction in viable counts at the end of exposure period due to encapsulation. Protection efficiency of the interpolymer complex was improved by addition of glyceryl monostearate (GMS). Gelatine capsules delayed release of bacteria from the interpolymer complex thus minimizing time of exposure to the detrimental conditions. Use of poly(caprolactone) (PCL), ethylene oxide-propylene oxide triblock copolymer (PEO-PPO-PEO) decreased the protection efficiency of the matrix. Interpolymer complex encapsulation showed potential for protection of probiotics and therefore for application in food and pharmaceuticals.

Introduction

Several probiotic lactic acid bacteria strains are available to consumers in both traditional fermented foods and in supplement form (Kourkoutas et al., 2005). Numbers of viable organisms in products are reduced due to exposure of products to different stresses during manufacturing, storage and consumption (Doleyres and Lacroix, 2005). However, probiotic cultures must remain viable in the environment where they act, to enable them to exert beneficial effect on the consumer (Schillinger, 1999).

These organisms must therefore survive the journey through the upper GIT so that they reach the colon in large numbers to colonize the host (Kailasapathy and Rybka, 1997, Alander et al., 1999, Lian et al., 2003, Hsiao et al., 2004, Mainville et al., 2005). On arrival in the colon, the ingested probiotics compete with other bacterial species already present for nutrients and adherence sites on the intestinal epithelium (Alander et al., 1999). Viability of these cultures in the GIT is affected mainly by gastric acid present in the stomach and bile in the duodenum (Rao et al., 1989, Lo et al., 2004, Mainville et al., 2005). This sensitivity of probiotics presents a challenge for their application in different industries (Hansen et al., 2002).

Several studies have shown poor survival of many strains of bifidobacteria in acidity and bile concentration present in the human GIT. Approaches for improving survival of these bacteria include selection of acid and bile resistant strains, use of O2 impermeable containers, two-step fermentations, stress adaptation, incorporation of micronutrients and microencapsulation (Picot and Lacroix, 2004).

Microencapsulation of bifidobacteria for improving gastrointestinal survival has been studied by various researchers (Rao et al., 1989, Sheu and Marshall, 1993, Cui et al., 2000, Lee and Heo, 2000, Sultana et al., 2000, Sun and Griffiths, 2000, Hansen et al., 2002, Guérin et al., 2003, Lian et al., 2003, Krasaekoopt et al., 2004, Capela et al., 2006). Most results indicated improved survival. However, most of the methods present problems for large scale production though promising on a laboratory scale (Picot and Lacroix, 2004). Also, these methods typically involve exposure of the probiotics to either water or organic solvent. This may compromise survival of encapsulated cells as they are sensitive to solvents and moisture. Thus, use of solvents should be avoided in order to improve survival. None of these previous studies reported survival of probiotics encapsulated in an interpolymer complex in supercritical CO2 (scCO2). This approach was reported for the first time by this group (Moolman et al., 2006). The aim of this study was to investigate the survival of interpolymer complex encapsulated Bifidobacterium longum Bb-46 in SGF and SIF, and to investigate effects of different modifications of the polymers on bacterial survival.

Section snippets

Bacterial cultures

B. longum Bb-46 was obtained in freeze-dried form from Chr-Hansen. The culture was stored at − 20 °C and then used as freeze-dried powder in encapsulation experiments.

Polymer formulations

Different polymer formulations used for encapsulation of bacteria are summarized in Table 1.

Preparation of ingredients for encapsulation

All equipment was wiped with 70% ethanol (NCP Alcohols) using a paper towel, and allowed to dry before contact with the materials. Poly (vinylpyrrolidone) (PVP) (Kollidon 12PF, mass-average molar mass 2000–3000 g/mol, BASF) was dried for 5 h

Survival in the basic system and with added copolymer

Probiotic cultures must withstand the acidic conditions of the stomach and reach the colon in large quantities (Kailasapathy and Rybka, 1997, Alander et al., 1999, Lian et al., 2003, Hsiao et al., 2004, Mainville et al., 2005). The encapsulated probiotic bacteria were therefore exposed to SGF and SIF to investigate the potential of the encapsulation for improving survival of the bacteria under the unfavourable conditions in upper sections of the GIT. Fig. 1 shows comparative counts for

Conclusions

Encapsulation in an interpolymer complex in scCO2 improved survival of B. longum Bb-46 through a simulated gastrointestinal envionment. The encapsulation method therefore has potential for application in food and pharmaceutical industries. Future in vitro studies will investigate the effect of the encapsulated bacteria on the microflora of the simulator of the human intestinal microbial ecosystem (SHIME) model. The effect of encapsulation on the shelf life of probiotics will also be

Acknowledgements

Thanks are due to Ellipsoid Technology (Pty) Ltd and the University of Pretoria for financial support.

References (25)

Cited by (31)

  • Bioencapsulation for probiotics

    2022, Smart Nanomaterials for Bioencapsulation
  • Survival of a norovirus surrogate on surfaces in synthetic gastric fluid

    2020, Journal of Hospital Infection
    Citation Excerpt :

    Currently, there is no standardized recipe for synthetic gastric fluid containing salts and proteinacious additives equivalent to those likely be present, in varying degrees, in an individual's stomach. However, previous research studies that have required the use of synthetic gastric fluid have used the same or similar recipes [4–6]. The following recipe used in this study is based on work by Tamplin [7] (all reagents used here are from Sigma-Aldrich Co. LLC.

  • Curcumin loaded nanostructured lipid carriers: In vitro digestion and release studies

    2019, Polyhedron
    Citation Excerpt :

    The nonionic surfactants has resistance to flocculation and coalescence in low pH due to their molecular structure [53]. It has been shown that acid stable GMS is a good candidate for construction of wall material for the fabrication of NLCs which might have also contributed to the stability of NLCs in SGM [54]. Both in vitro and in vivo stability is one of the major drawbacks that affects the therapeutic efficiencies of curcumin.

  • Current situation and perspectives in drug formulation by using supercritical fluid technology

    2018, Journal of Supercritical Fluids
    Citation Excerpt :

    Besides, higher active solute concentrations resulted in larger particles and higher encapsulation efficiency as well as active loads. In addition, it is worth noting that completely different natures of compounds, such as virus [46] and bacteria [47], have been coprecipitated by the PGSS process. Lastly, it should be pointed out that the plasticization of polymers using SC CO2 is also exploited in another type of process involving extruders [48].

  • Influence of the combination of probiotic cultures during fermentation and storage of fermented milk

    2014, Food Research International
    Citation Excerpt :

    There was no recovery of viable L. acidophilus cells after the pH levels were increased (in the enteric phase of the assay). However, other studies showed that recovery of this microorganism occurred after pH elevation (Buriti et al., 2010; Thantsha, Cloete, Moolman, & Labuschagne, 2009), and that it attributed to the temporary stress of probiotic cells due to the low pH levels. In these studies, the probiotic was in the presence of prebiotics (inulin, whey protein concentrate), or it was microencapsulated, which aided its survival at the low pH. In the present study, there were no compounds or ingredients to protect the probiotic cells and avoid cell death in the presence of low pH levels.

  • Viability of L. acidophilus microcapsules and their application to buffalo milk yoghurt

    2013, Food and Bioproducts Processing
    Citation Excerpt :

    This process forms small particles called microcapsules, which may release their content under specific conditions and speeds (Shahidi and Han, 1993). Microencapsulation of various bacterial cultures, including probiotics, has been a common practice for protecting probiotics extending their storage life (Favaro-Trindade and Grosso, 2000, 2002; Liserre et al., 2007; Shima et al., 2009; Thantsha et al., 2009; Sabikhi et al., 2010; Pedroso et al., 2012) and converting them into a powder form for convenient use (O’Riordan et al., 2001; Lian et al., 2003; Oliveira et al., 2007a,b). In addition, microencapsulation can promote controlled release and optimise the delivery of the bioactive to the site of action, thereby potentiating the efficacy of the respective probiotic strain (Favaro-Trindade et al., 2011).

View all citing articles on Scopus
View full text