Protein isolates from Cajanus cajan L. as surfactant for o:w emulsions: pH and ionic strength influence on protein structure and emulsion stability

Grape seed polyphenol water-in-oil emulsion: preparation and application in functional cookies

BACKGROUND

The study aimed to address the characteristics of grape seed polyphenols (GSPs), such as high hydrophilicity and poor stability in fats and oils, as well as the poor digestive properties of traditional cookies due to their high fat content. A GSP delivery system based on water-in-oil (W/O) emulsion technology was innovatively developed, aiming at solving the difficult problem of the limited application of GSPs in high-fat cookie systems. In this study, we explored the potential application of GSPs in functional cookie products by constructing a GSP-tea seed oil stabilized emulsion system.

RESULTS

Emulsion systems prepared by high-speed shear emulsification demonstrate superior performance (water-oil ratio of 2:8, polyglyceryl ricinoleate concentration of 50 g kg-1, sucrose concentration of 30 g kg-1, with 0.1% GSP added). The emulsion had an emulsification index of <1%, a zeta potential of 44.2 ± 0.5 mV and remained stable for many days after storage at 4 °C. Confocal laser scanning microscopy confirmed that the emulsion possessed a typical W/O structure, and GSP improved the thermal stability of the emulsion by 0.8 °C through the formation of a three-dimensional hydrogen bonding network, achieving a DPPH radical scavenging rate of 99.63%. After application in biscuit products, the shelf-life was extended by 37.32%, and the rapidly digestible starch (RDS) decreased to 41.17%.

CONCLUSION

We successfully constructed a GSP-enhanced functional emulsion system and elucidated its mechanism of action in improving product quality through a dual mechanism of amylase inhibition and antioxidant activity. This technology provides a new solution for developing healthy bakery products, although its industrial application still requires further work to address stability issues under extreme conditions. The findings of this study offer important guidance for applying plant polyphenols in food colloidal systems. © 2025 Society of Chemical Industry.

Evaluation of the performance of low-fat (oil-fat) dressings based on chemically modified Guayabo plantain starch (Musa paradisiaca L.)

Guayabo plantain (GP) starch was chemically modified by acetylation to evaluate its role as a stabilizer and emulsifier in low-fat dressings. Native starch (NS) from GP was chemically modified starch (MS), and its functional properties, such as water absorption index, water solubility index, swelling power, gelatinization temperature (Tg), were evaluated. Additionally, functional groups and morphology were identified using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy. Low-fat dressings were prepared using NS and MS at two concentrations, 2% and 3% (NS2, NS3, MS2, MS3), and the stability of the dressings was evaluated over a storage period of 28 days at 4 °C ± 2.0 °C. The percentage of acetylation and the degree of substitution obtained were 2.48% and 0.01, respectively, complying with current regulations. MS showed a higher amylose content (23.62 ± 1.89%) than NS (16.01 ± 0.43%). The Tg of MS decreased, and the appearance of bands at 1012 and 1723 cm-1 in the FT-IR spectra suggested a modification in the functional characteristics of starch due to acetylation. Emulsions of MS at 2% and 3% (MS2 and MS3) showed a smaller droplet size and higher interfacial dispersion. However, MS3 had higher viscosity, which contributed to an increase in hydrophobicity and delays in flocculation and subsequent coalescence. This research study provides useful information on the use of 3% MS dressings in new food formulations, reducing fat content while preserving functional characteristics, thus ensuring greater stability.

Encapsulation of lactic acid bacteria in W1/O/W2 emulsions stabilized by mucilage:pectin complexes

Opuntia silvestri mucilage obtained from dried stems was explored as an emulsifier to prepare double emulsions aiming to encapsulate Lactiplantibacillus plantarum CIDCA 83114. W1/O/W2 emulsions were prepared using a two-step emulsification method. The aqueous phase (W1) consisted of L. plantarum CIDCA 83114, and the oil phase (O) of sunflower oil. The second emulsion was prepared by mixing the internal W1/O emulsion with the W2 phase, consisting of 4 % polysaccharides, formulated with different mucilage:(citric)pectin ratios. Their stability was assessed after preparation (day 0) and during storage at 4 °C (28 days). Determinations included creaming index, color, particle size, viscosity, turbidity, and bacterial viability, along with exposure to simulated gastrointestinal conditions. Significant differences were evaluated by analysis of variance (ANOVA) and Duncan's test (P < 0.05). After 28 days storage, bacterial viability in the W1/O/W2 emulsions was above 6 log CFU/mL for all the pectin:mucilage ratios. Emulsions containing mucilage and pectins showed lower creaming indices after 15 days, remaining stable until the end of the storage period. Formulations including 1:1 pectin:mucilage ratio exhibited the highest bacterial viability under simulated gastrointestinal conditions and were more homogeneous in terms of droplet size distributions at day 0, hinting at a synergistic effect between mucilage components (e.g., proteins, Ca2+) and pectin in stabilizing the emulsions. These results showed that Opuntia silvestri mucilage enhanced the stability of emulsions during refrigerated storage, highlighting its potential for encapsulating lactic acid bacteria. This presents an economical and natural alternative to traditional encapsulating materials.

Thermal Gelation of Proteins from Cajanus cajan Influenced by pH and Ionic Strength

Cajanus cajan [pigeon pea (PP)] is an important legume crop for subsistence agriculture and its seeds are an alternative plant-based protein source. PP protein isolates (PPI) are able to form heat-induced gels that could be used for food applications. The aim of this work was to study the influence of pH (2.1, 3.9, 6.3, and 8.3) and ionic strength (μ) (0.10 and 0.54) on thermal stability and thermal gelation of PPI obtained by alkaline extraction (pH 8.0) and isoelectric precipitation. Thermal stability of PPI changed with pH variation at low ionic strength (μ = 0.10), decreasing this dependence with the increase of ionic strength (μ = 0.54). At μ = 0.10, gelation capacity of PPI was lower at pH 2.1 and pH 3.9. These gels presented a coarse network, which entails low WHC. At pH 6.3 and pH 8.3, gels showed a solid-like character with a compact and homogeneous matrix, with better WHC. At μ = 0.54, gel formation was favoured at pH 2.1 and pH 3.9. G'20/G'95 ratio values and differential solubility results suggest that hydrogen bonds and electrostatic interactions could play an important role in gel formation at pH 6.3 and pH 8.3.

Structural Modification of Jackfruit Leaf Protein Concentrate by Enzymatic Hydrolysis and Their Effect on the Emulsifier Properties

Jackfruit leaf protein concentrate (LPC) was hydrolyzed by pepsin (H–Pep) and pancreatin (H–Pan) at different hydrolysis times (30–240 min). The effect of the enzyme type and hydrolysis time of the LPC on the amino acid composition, structure, and thermal properties and its relationship with the formation of O/W emulsions were investigated. The highest release of amino acids (AA) occurred at 240 min for both enzymes. H–Pan showed the greatest content of essential and hydrophobic amino acids. Low β-sheet fractions and high β-turn contents had a greater influence on the emulsifier properties. In H–Pep, the β-sheet fraction increased, while in H–Pan it decreased as a function of hydrolysis time. The temperatures of glass transition and decomposition were highest in H–Pep due to the high content of β-sheets. The stabilized emulsions with H–Pan (180 min of hydrolysis) showed homogeneous distributions and smaller particle sizes. The changes in the secondary structure and AA composition of the protein hydrolysates by the effect of enzyme type and hydrolysis time influenced the emulsifying properties. However, further research is needed to explore the use of H–Pan as an alternative to conventional emulsifiers or ingredients in functional foods.

Effects of Tea Polyphenol Palmitate Existing in the Oil Phase on the Stability of Myofibrillar Protein O/W Emulsion

This study aimed to explore the effect of adding different concentrations (0, 0.01%, 0.03%, and 0.05% (w/w)) of tea polyphenol palmitate (TPP) in the oil phase on the emulsifying properties of 5 and 10 mg/mL myofibrillar protein (MP). Particle size results revealed that the flocculation of droplets increased as TPP concentration increased and that droplets in 5 mg/mL MP emulsions (25−34 μm) were larger than in 10 mg/mL MP emulsions (14−22 μm). The emulsifying activity index of 5 mg/mL MP emulsions decreased with increasing TPP concentration. The micrographs showed that the droplets of MP emulsions exhibited extensive flocculation at TPP concentrations >0.03%. Compared with 5 mg/mL MP emulsions, 10 mg/mL MP emulsions showed better physical stability and reduced flocculation degree, which coincided with lower delta backscattering intensity (ΔBS) and Turbiscan stability index values. The flow properties of emulsions can be successfully depicted by Ostwald−de Waele models (R2 > 0.99). The concentrations of TPP and protein affect the K values of emulsions (p < 0.05). Altogether, increased protein concentration in the continuous phase could improve emulsion stability by increasing viscosity, offsetting the adverse effects of TPP to a certain extent. This study is expected to promote the rational application of TPP in protein emulsion products of high quality and acceptability.

Impact of different ionic strengths on protein-lipid co-oxidation in whey protein isolate-stabilized oil-in-water emulsions

Protein-lipid co-oxidation of whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions with different ionic strengths (0, 100, 200, 300 and 400 mM) during storage were investigated. The results proved that changes in levels of adsorbed proteins induced by different ionic strengths could obviously affect the occurrence of protein-lipid co-oxidation. The level of oxidative stress was higher in adsorbed proteins extracted from control sample than in those extracted from emulsions with 300 or 400 mM ionic strengths. This was indicated by higher levels of N'-formyl-l-kynurenine (NFK) and carbonyl, lower fluorescence intensity and more serious unfolding of protein structure. Moreover, control sample showed the highest oxidative stability, which was indicated by lower levels of primary and secondary lipid oxidation products. These findings clearly illustrated that altered levels of adsorbed proteins induced by different ionic strengths play a crucial role in affecting protein-lipid co-oxidation in O/W emulsions.

Use of jackfruit leaf (Artocarpus heterophyllus L.) protein hydrolysates as a stabilizer of the nanoemulsions loaded with extract-rich in pentacyclic triterpenes obtained from Coccoloba uvifera L. leaf

This study aimed to evaluate the encapsulating potential of a jackfruit leaf protein hydrolysate, through obtaining pentacyclic triterpenes-rich extract loaded nanoemulsion. Response surface methodology (RSM) was used to optimize the conditions to obtain an optimal nanoemulsion (NE-Opt). The effect of protein hydrolysate concentration (0.5-2%), oil loaded with extract (2.5-7.5%), and ultrasound time (5-15 min) on the polydispersity index (PDI) and droplet size of the emulsion (D[3,2] and D[4,3]) was evaluated. RSM revealed that 1.25% protein hydrolysate, 2.5% oil, and ultrasound time of 15 min produced the NE-Opt with the lowest PDI (0.85), D[3,2] (330 nm), and D[4,3] (360 nm). Encapsulation efficiency and extract loading of the NE-Opt was of 40.15 ± 1.46 and 18.03 ± 2.78% respectively. The NE-Opt was relatively stable during storage (at 4 and 25 °C), pH, temperature, and ionic strength. Then, the protein hydrolysate could be used as an alternative to conventional emulsifiers.