Structural characterisation and cell viability of a spray dried probiotic yoghurt produced with goats' milk and Bifidobacterium animalis subsp. lactis (BI-07)

Stability and expression of K-ras mimotopes in freeze-dried recombinant Lactococcus lactis NZ3900-fermented milk powder during storage in vacuum packaging

AIMS

This study aims to evaluate the storage stability of the freeze-dried recombinant Lactococcus lactis NZ3900-fermented milk powder expressing K-ras (Kristen rat sarcoma viral oncogene homolog) mimotopes targeting colorectal cancer in vacuum packaging.

METHODS AND RESULTS

The freeze-dried L. lactis-fermented milk powder stored in 4-ply retortable polypropylene (RCPP)-polyamide (PA)-aluminium (AL)-polyethylene terephthalate (PET) and aluminium polyethylene (ALPE) was evaluated throughout 49 days of accelerated storage (38°C and 90% relative humidity). The fermented milk powder stored in 4-ply packaging remained above 6 log10 CFU g-1 viability, displayed lower moisture content (6.1%), higher flowability (43° angle of repose), water solubility (62%), and survivability of L. lactis after simulated gastric and intestinal digestion (>82%) than ALPE packaging after 42 days of accelerated storage. K-ras mimotope expression was detected intracellularly and extracellularly in the freeze-dried L. lactis-fermented milk powder upon storage.

CONCLUSIONS

This suggests that fermented milk powder is a suitable food carrier for this live oral vaccine.

Quality retention in pumpkin powder dried by combined microwave-convective drying

Three distinct drying methods, microwave drying (MWD), convective drying (CVD) and microwave-convective drying (MWCVD) with a grinding process were applied to obtain pumpkin powder. The effects of CVD (60, 70 & 80 °C), MWD (100 & 200 W) and MWCVD (100 W-60 °C, 100 W-70 °C, 100 W-80 °C, 200 W-60 °C, 200 W-70 °C, and 200 W-80 °C) applications on the physicochemical properties (water activity, bulk, tapped & particle densities, porosity, flowability, cohesiveness, swelling capacity, water holding capacity and water solubility index), color values (L ^* , a ^* , b ^* , C, α ^o and Δe), bioactive compounds (5-Hydroxymethyl-2-furfural (HMF), total phenolic content (TPC) and antioxidant capacity (DPPH and ABTS)) of the eleven pumpkin fruit powders were compared. The MWCVD, namely pumpkin powders dried at 200 W-80 °C resulted in shorter drying times with high-quality dried pumpkin powders. The bulk, tapped and particle densities of pumpkin powders at 200 W-80 °C by MWCVD were 0.56, 0.66 and 1.74 g/cm³, respectively. These values are indicators of the good porosity (61.82%) of pumpkin powders. In addition, the highest TPC (1277.08 mg GA/100 g dw) and ABTS (126.99 ± 3.31 µmol Trolox/g dw) was observed for microwave-convective dried pumpkin powders at 200 W-80 °C. On the other hand, the lowest HMF level (10.12 ± 1.78 mg/kg dw) was found for the pumpkin poowders dried by MWCVD at 200 W-80 °C. In overall, dried pumpkin powders by a MWCVD method can be employed to acquire a high-quality food material along with an enhanced physicochemical properties, color and bioactive components.

Studies on survivability, storage stability of encapsulated spray dried probiotic powder

Awareness about probiotic food and their health benefits is increasing tremendously. However, probiotics have to withstand the harsh conditions that come across during their processing, handling, storage, and gastrointestinal conditions. Encapsulating technologies can be used to protect the probiotics during their passage through the gastrointestinal system of the human gut. Probiotics as an ingredient in dry powder form can be easily handled, stored, and used in developing the probiotic functional products. In the present study, probiotic cells (Lactobacillus acidophilus) were encapsulated by spray drying technology to produce a probiotic powder using 20% of maltodextrin and varied concentrations of gum arabic. The effect of processing conditions such as inlet air temperature (130-150 °C) and gum arabic concentration (0-10%) on the encapsulation efficiency and physical properties were studied. Further, the free and encapsulated probiotic cells were exposed to the simulated-gastric intestinal (SGI) fluid conditions and different storage conditions for their viability. For all the tested formula, moisture content, water activity, encapsulation efficiency, hygroscopicity, and wettability obtained were in the range of 4.59-9.05% (w.b.), 0.33-0.52, 65-89.15%, 12-21.15 g H2O/100g dry weight, and 116 s-353 s, respectively. The Fourier transform infrared (FTIR) results have shown that gum arabic and maltodextrin have structural stability during spray drying. The encapsulated probiotic cells have shown a positive effect and exhibited better viability after exposure to a SGI solution at different pH levels and duration compared to free cells. The viability of encapsulated cells stored at refrigerated condition (4 °C) was found to be higher than the viability of cells stored at room temperature (25 °C).

Encapsulation of Lactobacillus acidophilus NCDC 016 cells by spray drying: characterization, survival after in vitro digestion, and storage stability

In the present study, probiotic cells (Lactobacillus acidophilus) were encapsulated by spray drying technology to produce a probiotic powder using 20% maltodextrin and varied concentrations of gum arabic. The effects of processing conditions such as inlet air temperature (130-150 °C) and gum arabic concentration (0-10%) on the encapsulation efficiency, physical properties, and morphology were studied. For all the tested formulae, the moisture content, water activity, encapsulation efficiency, hygroscopicity, and wettability obtained were in the range of 4.59-9.05% (w.b.), 0.33-0.52, 65-89.15%, 12 to 21.15 g H2O per 100 g dry weight, and 116 s to 353 s, respectively. The Fourier transform infrared (FTIR) results have shown that gum arabic and maltodextrin show structural stability during spray drying. The encapsulated probiotic cells exhibited better viability of 4.03, 4.68, and 5.34 log CFU g-1 after 3 h of exposure to a simulated gastric fluid (SGF) solution at pH levels of 1, 1.5, and 2, respectively, compared to free cells. The viability of encapsulated cells stored for 12 weeks under refrigerated conditions (4 °C) and at room temperature (25 °C) was found to be 6.05 log CFU g-1 and 1.24 log CFU g-1, respectively.

Evaluating the Effect of Electromagnetic Stir-Frying Barley Flour on Yoghurt Quality

There is a great interest in the use of natural ingredients as functional components in food products. Barley is considered as a natural thickener substitute due to its high dietary fiber content. In this work, electromagnetic stir-frying barley flour (ESBF) was developed and applied in yoghurt. The yoghurt samples were prepared by adding 10, 20, 30, and 40 g L−1 of ESBF, respectively; the control sample was made with 20 g L−1 of whey protein concentrate (WPC), and the yoghurt without any thickener was regarded as blank. The rheological, microstructural, and sensory properties were investigated to evaluate the effect of ESBF on yoghurt quality. Compared to the blank and control samples, the yoghurt with ESBF had higher contents of total solids ranging from 232.5 ± 1.2 g·kg−1 mix to 241.6 ± 1.4 g·kg−1 mix, and crude fiber ranged from 1.6 ± 0.4 g·kg−1 mix to 4.5 ± 0.6 g·kg−1 mix according to the added amount of ESBF. Representing the rheological characteristics of yoghurt, the storage modulus (G′), loss modulus (G″), and apparent viscosity increased with the amount of ESBF. Scanning electron microscope images exhibited that both WPC and barley starch were distributed uniformly in a yoghurt sample, with starch strands between and attached to the protein aggregates reducing the free end. In addition, increased stability of viscosity, water-holding capacity, and bacteria were obtained with the addition of ESBF whether after postripening or during storage of yoghurt. The highest viscosity was up to 3305 MPa s in the yoghurt with 4% ESBF. Current results indicate that ESBF could be used as a suitable natural ingredient and thickener in food.

Probiotics in Goat Milk Products: Delivery Capacity and Ability to Improve Sensory Attributes

Dairy foods, particularly those of bovine origin, are the predominant vehicles for delivery of probiotic bacteria. Caprine (goat) milk also possesses potential for successful delivery of probiotics, and despite its less appealing flavor in some products, the use of goat milk as a probiotic carrier has rapidly increased over the last decade. This review reports on the diversity, applicability, and potential of using probiotics to enhance the sensory properties of goat milk and goat milk-based products. A brief conceptual introduction to probiotic microorganisms is followed by an account of the unique physicochemical, nutritive, and beneficial aspects of goat milk, emphasizing its advantages as a probiotic carrier. The sensory properties of probiotic-enriched goat milk products are also discussed. The maintenance of probiotic viability and desirable physicochemical characteristics in goat milk products over shelf life is possible. However, the unpleasant sensory features of some goat milk products remain a major disadvantage that hinder its wider utilization. Nevertheless, certain measures such as fortification with selected probiotic strains, inclusion of fruit pulps and popular flavor compounds, and production of commonly consumed tailor-made goat milk-based products have potential to overcome this limitation. In particular, certain probiotic bacteria release volatile compounds as a result of their metabolism, which are known to play a major role in the aroma profile and sensory aspects of the final products.

Production of a Functional Frozen Yogurt Fortified with Bifidobacterium spp

Frozen dairy products have characteristics of both yogurt and ice cream and could be the persuasive carriers of probiotics. Functions of the frozen yogurt containing viable bifidobacterial cells are recognized and favored by the people of all ages. We developed a kind of yogurt supplemented by Bifidobacterium species. Firstly, five strains of Bifidobacterium spp. (Bifidobacterium bifidum ATCC 11547, Bifidobacterium longum ATCC 11549, Bifidobacterium infantis ATCC 11551, Bifidobacterium adolescentis ATCC 11550, and Bifidobacterium breve ATCC 11548) were evaluated based on the feasibility criteria of probiotics, comprising acid production, bile tolerance, and adhesion to epithelial cells. Formerly, we combined the optimum strains with yogurt culture (Lactobacillus delbrueckii subsp. bulgaricus EMCC 11102 and Streptococcus salivarius subsp. thermophilus EMCC 11044) for producing frozen yogurt. Finally, physiochemical properties and sensory evaluation of the frozen yogurt were investigated during storage of 60 days at -18°C. Results directed that Bifidobacterium adolescentis ATCC 11550 and Bifidobacterium infantis ATCC 11551 could be utilized with yogurt culture for producing frozen yogurt. Moreover, the frozen yogurt fermented by two bifidobacterial strains and yogurt culture gained the high evaluation in the physiochemical properties and sensory evaluation. In summary, our results revealed that there was no significant difference between frozen yogurt fermented by Bifidobacterium spp. and yogurt culture and that fermented by yogurt culture only.