Lactobacillus plantarum survival during the osmotic dehydration and storage of probiotic cut apple

Alginate coatings applied on apple cubes as a vehicle for Lacticaseibacillus casei: probiotic viability and overall quality of a new functional product

BACKGROUND

Worldwide, vegan and vegetarian lifestyles, as well as food allergies and intolerance (e.g. lactose intolerance and milk protein allergy) demand the development of alternatives to dairy-based probiotic foods. In the present study, probiotic Lacticaseibacillus casei CECT 9104 was added to alginate-based edible coatings enriched with inulin and oligofructose and applied to fresh-cut apple. Microbiological, physicochemical and sensory quality parameters of the apple cubes were monitored during 8 days of refrigerated storage. Lacticaseibacillus casei was tested for its antagonistic effect against inoculated Listeria innocua and Escherichia coli O157:H7. The viability of the probiotic strain during refrigerated storage and after simulated gastrointestinal digestion (GID) was evaluated.

RESULTS

After 8 days of storage, 9.52-9.64 log colony-forming units (CFU) g-1 of L. casei were detected in apple samples. The functional apple cubes retained 8.31-8.43 log CFU g-1 of the probiotic after GID, without a significant effect of prebiotic addition. The microbiological quality and nutritional properties were maintained by the use of active coatings, whereas the sensory quality decreased after 8 days of storage. A bactericidal effect was exerted by the probiotic strain loaded in the coating against L. innocua artificially inoculated on apple cubes. Escherichia coli O157:H7 counts were reduced by 2.5 log after 8 days.

CONCLUSION

This study has demonstrated the suitability of apple cubes as an alternative matrix to milk for carrying probiotic L. casei CECT 9104 and prebiotics, offering a promising alternative for the development of plant-based functional foods. © 2024 Society of Chemical Industry.

Development of an Apple Snack Enriched with Probiotic Lacticaseibacillus rhamnosus: Evaluation of the Refractance Window Drying Process on Cell Viability

The objective of this study was to develop a dried apple snack enriched with probiotics, evaluate its viability using Refractance Window (RWTM) drying, and compare it with conventional hot air drying (CD) and freeze-drying (FD). Apple slices were impregnated with Lacticaseibacillus rhamnosus and dried at 45 °C using RWTM and CD and FD. Total polyphenol content (TPC), color (∆E*), texture, and viable cell count were measured, and samples were stored for 28 days at 4 °C. Vacuum impregnation allowed for a probiotic inoculation of 8.53 log CFU/gdb. Retention values of 6.30, 6.67, and 7.20 log CFU/gdb were observed for CD, RWTM, and FD, respectively; the population in CD, RWTM remained while FD showed a decrease of one order of magnitude during storage. Comparing RWTM with FD, ∆E* was not significantly different (p < 0.05) and RWTM presented lower hardness values and higher crispness than FD, but the RWTM-dried apple slices had the highest TPC retention (41.3%). Microstructural analysis showed that RWTM produced a smoother surface, facilitating uniform moisture diffusion and lower mass transfer resistance. The effective moisture diffusion coefficient was higher in RWTM than in CD, resulting in shorter drying times. As a consequence, RWTM produced dried apple snacks enriched with probiotics, with color and TPC retention comparable to FD.

Investigating the Probiotic Potential of Vegan Puree Mixture: Viability during Simulated Digestion and Bioactive Compound Bioaccessibility

This study aimed to develop a fermented puree mixture containing plant-based ingredients and potential probiotic strains Lacticaseibacillus rhamnosusK3 and Lactobacillus johnsonii K4. The survival of potential probiotic strains, changes in sugar and organic acid concentrations, bioaccessibility of polyphenols, and antioxidant capacity after simulated digestion were examined with sensory quality. The mixture of apple puree, chia seeds, and oat bran or oat flakes was fermented. The sensory quality of the puree mixture was assessed by the quantitative descriptive profile (QDP) method. In vitro digestion was simulated using a static gastrointestinal model. Antioxidant capacity and total polyphenol content were analyzed before and after the digestion phases. All samples changed sensory profiles after fermentation. The overall quality was above six out of ten for every product. Fermentation also changed the organic acid composition, with significant increases in lactic, succinic, and acetic acids. After the digestion process, the survival rate remained above 5.8 log10 CFU/g. As a result of fermentation with potential probiotics, the bioaccessibility of the total phenolics and antioxidant activity increased. These results showed that the addition of potential probiotic strains increases nutritional value and could help with healthy nourishment habits. This knowledge can guide the development of consumer-satisfying products in the food industry, expanding the probiotic food market with innovative alternatives.

Co-encapsulation of Lactobacillus plantarum and bioactive compounds extracted from red beet stem (Beta vulgaris L.) by spray dryer

Probiotic bacteria and bioactive compounds obtained from plant origin stand out as ingredients with the potential to increase the healthiness of functional foods, as there is currently a recurrent search for them. Probiotics and bioactive compounds are sensitive to intrinsic and extrinsic factors in the processing and packaging of the finished product. In this sense, the present study aims to evaluate the co-encapsulation by spray dryer (inlet air temperature 120 °C, air flow 40 L / min, pressure of 0.6 MPa and 1.5 mm nozzle diameter) of probiotic bacteria (L.plantarum) and compounds extracted from red beet stems (betalains) in order to verify the interaction between both and achieve better viability and resistance of the encapsulated material. When studying the co-encapsulation of L.plantarum and betalains extracted from beet stems, an unexpected influence was observed with a decrease in probiotic viability in the highest concentration of extract (100 %), on the other hand, the concentration of 50 % was the best enabled and maintained the survival of L.plantarum in conditions of 25 °C (63.06 %), 8 °C (88.80 %) and -18 °C (89.28 %). The viability of the betalains and the probiotic was better preserved in storage at 8 and -18 °C, where the encapsulated stability for 120 days was successfully achieved. Thus, the polyfunctional formulation developed in this study proved to be promising, as it expands the possibilities of application and development of new foods.

Osmotic dehydration and convective drying of kiwifruit (Actinidia deliciosa) - The influence of ultrasound on process kinetics and product quality

The aim of this study was to assess the impact of ultrasound on two subsequent processes - initial osmotic dehydration and convective drying of kiwifruit (Actinidia deliciosa). The effect of ultrasound (at a frequency of 25 kHz) was assessed both in terms of process kinetics and product quality. During the study, three different osmotic agents were used - erythritol, sorbitol, and sucrose - in an aqueous solution at a concentration of 50% (w/w). The essential kinetic parameters were analyzed - water loss and increase of dry matter during osmotic dehydration, and evolution of moisture content and temperature of samples during convective drying (drying curves). Product quality was assessed on the basis of color, water activity, and content of relevant bioactive components - polyphenols and carotenoids. It was found that the application of ultrasound during osmotic dehydration resulted in higher water loss and solid gain. This surely results from the phenomena occurring during the propagation of the elastic waves in the liquid medium (mainly related to cavitation) and enhancement of the mass transfer. The use of ultrasound during convective drying also had a positive effect on the kinetics of this process. In most cases, during the ultrasonically assisted drying operations, a significant increase in drying rate was observed, leading to a reduction in drying time. This may be due to the intensification of both heat and mass transfer as a result of the mechanical and thermal effects of ultrasound. The assessment of product quality showed that the use of sugar alcohols was a good alternative to sucrose, and ultrasound-assisted convective drying increased the retention of valuable carotenoids and polyphenols. Moreover, in all dried kiwifruit slices, water activity was below 0.6, which can guarantee the microbiological stability of the tested samples.

Quantifying the impact of eight unit operations on the survival of eight Bacillus strains with claimed probiotic properties

This study assessed the impact of eight unit operations [slow pasteurization, high-temperature short time (HTST) pasteurization, cooking, baking, drying, fermentation, supercritical carbon dioxide (CO₂), irradiation and extrusion] in different food matrices (milk, orange juice, meatballs, bread, crystallized pineapple, yogurt, orange juice, ground black pepper, snacks, and spaghetti) on the resistance of eight (Bacillus flexus Hk1 Bacillus subtilis Bn1, Bacillus licheniformis Me1, Bacillus mojavensis KJS3, Bacillus subtilis PXN21, Bacillus subtilis PB6, Bacillus coagulans MTCC 5856 and Bacillus coagulans GBI-30, 6086) Bacillus strains with claimed probiotic properties (PB). The number of decimal reductions (γ) caused by the unit operations varied (p < 0.05) amongst the PB. Most of the unit operations caused ≤ 2 γ of PB in the food matrices evaluated. Irradiation caused up to 4.9 γ (p < 0.05) amongst the PB tested. B. subtilis Bn1, B. mojavensis KJS3, B. licheniformis Me1, and B. coagulans GBI-30 showed higher resistance to most of the tested unit operations. These results indicate that the choice of PB for application in foods should also be based on their resistance to unit operations employed during processing. Finally, the high resistance of PB to the unit operations tested comprise valuable data for the development and diversification of probiotic foods with sporeforming strains with claimed probiotic properties.

Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food

Optimization of food storage has become a central issue for food science and biotechnology, especially in the field of functional foods. The aim of this work was to investigate the influence of different storage strategies in a fermented food product (FFP) and further determine whether the regular storage (room temperature (RT) and standard packaging (SP)) could be refined. Eight experimental conditions (four different temperatures × two packaging) were simulated and changes in FFP's microbial ecology (total bacteria, lactic acid bacteria (LAB), and yeasts) and physicochemical characteristics (pH and moisture content (MC)) were determined following 1, 3, 6, and 12 months. All conditions tested showed a decline in microbial content due to the effect of the temperature, 37 °C being the most detrimental condition, while -20 and 4 °C seemed to be better than RT in some parameters. Vacuum packaging (VP) only had a major effect on MC and we found that VP preserved greater MC values than SP at 3, 6, and 12 months. The correlation analysis revealed that total bacteria, LAB, and yeasts were positively associated, and also both pH and MC showed a correlation. According to our results and with the purpose to maintain the load of viable microorganisms, we observed that the best storage conditions should contemplate SP and freezing or cooling temperature during a period no longer than 3 months.

Lactobacillus plantarum 299V improves the microbiological quality of legume sprouts and effectively survives in these carriers during cold storage and in vitro digestion

Probiotics improve consumers' health and additionally may positively influence the microbiological and organoleptic quality of food. In the study, legume sprouts were inoculated with Lactobacilllus plantarum 299V to produce a new functional product ensuring the growth and survival of the probiotic and high microbiological quality of the final product. Legume sprouts, which are an excellent source of nutrients, were proposed as alternative carriers for the probiotic. The key factors influencing the production of probiotic-rich sprouts include the temperature (25°C) of sprouting and methods of inoculation (soaking seeds in a suspension of probiotics). Compared to the control sprouts, the sprouts enriched with the probiotic were characterized by lower mesophilic bacterial counts. In the case of fresh and stored probiotic-rich sprouts, lactic acid bacteria (LAB) accounted for a majority of total microorganisms. The Lb. plantarum population was also stable during the cold storage. The high count of LAB observed in the digest confirmed the fact that the studied sprouts are effective carriers for probiotics and ensure their survival in the harmful conditions of the digestive tract in an in vitro model. Enrichment of legume sprouts with probiotics is a successful attempt and yields products for a new branch of functional foods.

Lactobacillus plantarum with Functional Properties: An Approach to Increase Safety and Shelf-Life of Fermented Foods

Lactobacillus plantarum (widespread member of the genus Lactobacillus) is one of the most studied species extensively used in food industry as probiotic microorganism and/or microbial starter. The exploitation of Lb. plantarum strains with their long history in food fermentation forms an emerging field and design of added-value foods. Lb. plantarum strains were also used to produce new functional (traditional/novel) foods and beverages with improved nutritional and technological features. Lb. plantarum strains were identified from many traditional foods and characterized for their systematics and molecular taxonomy, enzyme systems (α-amylase, esterase, lipase, α-glucosidase, β-glucosidase, enolase, phosphoketolase, lactase dehydrogenase, etc.), and bioactive compounds (bacteriocin, dipeptides, and other preservative compounds). This review emphasizes that the Lb. plantarum strains with their probiotic properties can have great effects against harmful microflora (foodborne pathogens) to increase safety and shelf-life of fermented foods.

Functional Dehydrated Foods for Health Preservation

The market of functional foods has experienced a huge growth in the last decades due to the increased consumers’ awareness in a healthy lifestyle. Dried fruits constitute good snacks, in alternative to salty or sweet ones, and food ingredients due to their taste and nutritional/health benefits. Bioactive molecules are interesting sources to develop functional foods, as they play a major role in improving the health status and minimizing disease risks. The bioactive compounds most widely discussed in literature are presented in this review, for example, polyphenols, phytosterols, and prebiotics. Different technologies to dry bioproducts for producing functional foods or ingredients are presented. New drying techniques for the preservation of bioactive compounds are proposed, focusing more specifically on dielectric drying. A discussion on the techniques that can be used to optimize drying processes is performed. An overview on dehydrated plant based foods with probiotics is provided. The microorganisms used, impregnation procedures, drying methods, and evaluated parameters are presented and discussed. The principal bioactive compounds responsible for nutritional and health benefits of plant derived dried food products—fruits and vegetables, fruits and vegetables by-products, grains, nuts, and algae—are presented. Phytochemical losses occurring during pretreatments and/or drying processes are also discussed.