Utilization of some plant polysaccharides for improving yoghurt consistency

Evaluation of lupine seeds (Lupinus albus L.) neutral extract as a texture improver in low-fat yogurt production

Aqueous lupine seeds (Lupinus albus L.) extracts were evaluated as a natural fat substitute in low-fat yogurt production. Thus, the chemical composition, particle size, molecular weight, total phenolic (TPC), and total flavonoids (TFC) of the selected extract were estimated. Also, the antimicrobial activity and antioxidant capacity of selected extract were investigated. Yogurt with neutral lupine extract (NeLP) had the highest all sensorial attributes compared to other extracts. Also, the incorporation of NeLP during low-fat yogurt processing increased the solid content, and viscosity, as well as improved the textural profile and sensorial attributes without any negative effect on the yogurt's color. SEM micrographs of NeLP-yogurt microstructure showed a matrix characterized by large fused casein micelles clusters with comparatively lower porosity compared to control yogurt (without NeLP). The chemical composition of NeLP indicated that the major sugar constituents are glucose and galactose with different molar fractions. The molecular weight of NeLP is 460.5 kDa with a particle size of 1519.9 nm. Also, IC50 of NeLP is 0.589 mg/ml, while TPC and TFC are 7.17, and 0.0137 g/100 g sample, respectively. Hence, lupine neutral extract (0.25%) could be used as a fat replacer or texture improver ingredient in such low-fat yogurt which led to improved its characteristics without any negative defect during 7 days at 5 °C.

Biochemical characterization and insights into the potency of the acidic Aspergillus niger NRC114 purified α-galactosidase in removing raffinose family oligosaccharides from soymilk yogurt

BACKGROUND

Because humans lack α-galactosidase, foods containing certain oligosaccharides from the raffinose family, such as soybeans and other legumes, may disrupt digestion and cause flatulence.

RESULTS

Aspergillus niger NRC114 α-galactosidase was purified using protein precipitation, gel filtration, and ion exchange chromatography steps, which resulted in a 123-fold purification. The purified enzyme was found to be 64 kDa using the SDS-PAGE approach. The optimum pH and temperature of the purified α-galactosidase were detected at pH 3.5 and 60 ºC, respectively. The pure enzyme exhibited potent acidic pH stability at pH 3.0 and pH 4.0 for 2 h, and it retained its full activity at 50 ºC and 60 ºC for 120 min and 90 min, respectively. The enzyme was activated using 2.5 mM of K⁺, Mg²⁺, Co²⁺, or Zn²⁺ by 14%, 23%, 28%, and 11%, respectively. The K_m and V_max values of the purified enzyme were calculated to be 0.401 µM and 14.65 μmol min^-1, respectively. The soymilk yogurt showed an increase in its total phenolic content and total flavonoids after enzyme treatment, as well as several volatile compounds that were detected and identified using GC-MS analysis. HPLC analysis clarified the enzymatic action in the hydrolysis of raffinose family oligosaccharides.

CONCLUSION

The findings of this study indicate the importance of A. niger NRC114 α-galactosidase enzyme for future studies, especially its applications in a variety of biological fields.

Preliminary Studies of Bio-Fortification of Yoghurt with Chromium

Yoghurt is a delectable fermented milk product suitable for all ages. Chromium (Cr), a trace mineral is found in two forms: trivalent and hexavalent. Recent studies have shown that the Cr (III), or chromium picolinate (Cri), is beneficial for carbohydrate metabolism. Thus, Cr supplements are used to treat diabetes and manage blood sugar. However, the effect of the incorporation of Cri on starter growth and the quality of yoghurt still needs to be determined. In this study, we aim to produce Cr (CrPi)-fortified yoghurt to fulfil the proposed recommended daily allowance (RDA) of Cr (35–50 µg/day for adults). Additionally, it might act as a nutraceutical for persons with special medical conditions, such as patients with obesity or type 2 diabetes mellitus disease. In this respect, the effect of different concentrations of CrPi, (1, 2, 5, 10, 20 ppm) chromium chloride [Cr (III)] (1, 2, 3, 4, 5 ppm), and potassium chromate [Cr (VI)] (1, 2 ppm) on the activity of yoghurt starter culture were investigated in vitro on de Man, Rogosa, and Sharpe (MRS) media. Compared to the control (without Cr), the obtained data revealed significant inhibition of the yoghurt starter culture by Cr (VI) at 2 ppm compared to Cr (III), which did not affect the bacterial growth up to 5 ppm and was comparable with CrPi [Cr (III)]. We also produced yoghurt supplemented with two doses of Cr (0.25 and 0.5 ppm). We did not observe any significant differences in the physicochemical, rheological, microbiological, and sensory properties of the Cr-fortified yoghurt and the control up to 2 weeks in cold storage. These results clearly indicate that CrPi (0.25 and 0.5 ppm) can be used to manufacture yoghurt with the RDA for intact Cr without affecting its quality.

Probiotic Yoghurt Made from Milk of Ewes Fed a Diet Supplemented with Spirulina platensis or Fish Oil

Purpose

Yoghurt is a widely consumed dairy product around the world. It has healing properties and characteristics that are important for human health. Our goal was to see how using ewes' milk fed Spirulina platensis (SP) or fish oil (FO)-supplemented diets affected the chemical, physical, and nutritional properties of yoghurt, as well as the activity and survival of starter and probiotic bacteria during storage.

Methods

The collected milk from each ewe group was preheated to 65 °C and homogenized in a laboratory homogenizer, then heated to 90 °C for 5 min, cooled to 42 °C, and divided into two equal portions. The first portion was inoculated with 2.0% mixed starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus, 1:1), whereas the second was inoculated with 2% mixed starter culture and 1% Bifidobacterium longum as a probiotic bacteria.

Results

SP yoghurt had the highest levels of short chain-FA, medium chain-FA, mostly C10:0, and long chain-FA, namely C16:0, C18:2 and the lowest levels of C18:0 and C18:1, followed by FO yoghurt. The addition of SP or FO to ewes' diets resulted in yoghurt with higher viable counts of L. bulgaricus and S. thermophilus, which were still >107 cfu/g at the end of storage, as well as a higher level of acetaldehyde content (P<0.05) as a flavor compound, than the control (C) yoghurt. The viscosity of SP yoghurt was higher than that of FO and C yoghurt; the difference was not significant. The addition of B. longum, a probiotic bacteria, to all yoghurt samples, improved antioxidant activities, particularly against ABTS• radicals, but reduced SP yoghurt viscosity. When B. longum was added, acetaldehyde content increased from 39.91, 90.47, and 129.31 μmol/100g in C, FA, and SP yoghurts to 46.67, 135.55, and 144.1 μmol/100g in probiotic C, FA, and SP yoghurts, respectively. There was no significant difference in sensory qualities among all the yoghurt samples during all storage periods.

Conclusions

Supplementing the ewes' diets with Spirulina platensis or fish oil can change the fatty acid composition of the resulting yoghurt. The starter culture's activity, flavor compounds, and some chemical, physical, and antioxidant properties of milk produced from these diets can all be improved, particularly in yoghurt treated with probiotic bacteria (B. longum).

Preparation, structural characteristics, and application of taro polysaccharides in food

Taro, a staple food for residents in Africa and parts of Asia, is an important source of carbohydrate. China has abundant taro resources. Taro contains polysaccharide, vitamins, minerals and other substances. Taro polysaccharides, as a significant active ingredient in taro, are mainly composed of monosaccharide units such as glucose, galactose, arabinose, mannose, and so on. Taro polysaccharides have antioxidant, lipid-lowering, and immunomodulatory effects. In today's world, people are interested in food containing natural ingredients, which stimulates the potential of taro polysaccharides in the food, pharmaceutical, medical, and other fields. Herein, the extraction and purification, structural characterization, functional activity, and application of taro polysaccharides are reviewed to strengthen the cognition of taro polysaccharides. It provides references for further research and development of taro polysaccharides. © 2022 Society of Chemical Industry.

Effects of gellan gum and inulin on mixed-gel properties and molecular structure of gelatin

Gellan gum (GG) is often added to gelatin (GL) to improve the gel property. GG-based or inulin (IL)-based hydrogels were developed. Rigid and brittle gels or smooth and delicate gels were prepared with GG and IL, respectively. This study aimed to explore the properties and interaction mechanisms of the mixed-gel system containing GL, GG, and IL, in which different ratios of GG-IL (0.4%) (10:0, 8:2, 6:4, 5:5, 4:6, 2:8, and 0:10) were added to GL (6%). Texture profiles, rheological properties, water mobility, intermolecular forces, circular dichroism (CD) spectra, and microstructures were analyzed. The results showed that addition of GG-IL could improve the hardness, chewiness, and cohesiveness of mixed-gel, besides maintaining appropriate springiness. Water mobility of the mixed-gel decreased while viscoelasticity increased upon the addition GG. At GG:IL = 2:8, the melting temperature of mixed-gel was far higher than that of GL gel itself. The GL-GG-IL gel showed decrease in nonspecific bonding and increase in hydrogen bonding compared with the GL gel. CD spectra indicated the promotion of GL unfolding by GG, hence suggesting the binding of GG to GL; binding ability was better at GG:IL >5:5. Cryo-SEM provided evidence for the formation of cross-linked network within GL-GG-IL. Overall, we concluded that addition of GG-IL to GL system would be most suitable for improving the properties of mixed-gel. This finding may be potentially applicable in the further development of gel food products, such as meat jellies and gummy jellies.

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.

Optimal Ultrasound-Assisted Process Extraction, Characterization, and Functional Product Development from Flaxseed Meal Derived Polysaccharide Gum

Flaxseed (Linum usitatissimum L.) has several health-promoting applications as dietary food ingredient supplementation, owing to presence of high quality of oil, polyunsaturated fatty acids, high dietary fiber and protein contents. The presence of different anti-nutritional components, for example cyanogens (HCN) and tannins in meal, limits its application for food purposes. The study was conducted to observe the effect of ultrasound-assisted extraction on polysaccharide gums (PSG) yield using response surface methodology. The selected variables were sonication temperature (°C), water to meal ratio, sonication amplitude level (%), sonication pH, and sonication time (min). Ultrasound-assisted extraction significantly reduced the anti-nutritional components like HCN and tannins. The extracted PSG yield from partially defatted flaxseed meal (PDFM) samples varied to a minimum of 7.24% to a maximum of 11.04% when extraction temperature (°C) and amplitude level (%) varied from −1 to +1 and keeping all other variables constant at mean value. Physiochemical and functional properties of extracted PSG were studied. Yoghurt with different treatment combinations were prepared by supplementing flaxseed-derived PSG as stabilizer ranging from 0.25% to 1.5%, keeping baseline samples without PSG as control. Functional properties of PSG-supplemented yoghurt such as pH, syneresis, and viscosity were determined to assess the influence of PSG supplementation on yoghurt quality. In the organoleptic behavior of PSG-supplemented yoghurt, no adverse effect on the flavor have been observed, but the textural properties vary significantly among different treatments. Overall, the acceptability of 1% PSG-supplemented yoghurt was significantly higher than other treatments.

Mucilaginous polysaccharides from vegetative parts of Bixa orellana L.: Their characterization and antioxidant potential

The aim of this study was to extricate adhesive mucilaginous polysaccharides (MPS) from vegetative parts of Bixa orellana and furthermore to explore proximate analysis and antioxidant potentials. The ethanol precipitated mucilage concentrates of leaf holds 57.7% ± 3.2% moisture, 31.7 ± 1.61 g/100 g aggregate starch content, 23.6 ± 0.07 g/100 g reducing sugar content, 14.5 ± 2.0 g/100 g pentose content, 9.37 ± 0.56 g/100 g uronic acid substance, 10.6 ± 0.98 g/100 g total phenolic content, and 36.9 ± 0.52 mg/100 g total protein content. In contrasted with twigs, the leaves MPS demonstrated two folds increment in phenolic content. The sugar composition characteristics of MPS by gas liquid chromatography demonstrated a noteworthy content of xylose (163.5 ± 6.6 mg/100 g), mannose (17.2 ± 0.6 mg/100 g), and galactose (13.7 ± 0.4 mg/100 g) in leaf. The MPS extract of leaves exhibited a dose-dependent antioxidant activity and free radical scavenging ability. The data obtained in this study open a new avenue to further investigate the broad applications of these annatto dye yielding plant polysaccharides. PRACTICAL APPLICATIONS: The mucilaginous polysaccharides (MPS) from plant sources are being used for different applications in food, pharma, and cosmetic enterprises. Nowadays there is a developing enthusiasm for MPS for their dietary and medicinal advantages. Particularly dietary polysaccharides are known to evoke immunomodulatory and anti-inflammatory properties. Here, we present the leaf and twig parts of Bixa orellana as rich sources of MPS, the MPS characterization and also antioxidant potential, which could substantiate B. orellana MPS as functional ingredients and furthermore in nourishment industry for expanding dairy foods consistency.