Effect of guar gum on stability and physical properties of orange juice

Effects of Ultrasonic Treatment on Physical Stability of Lily Juice: Rheological Behavior, Particle Size, and Microstructure

The aim of this study was to investigate the rheological properties, particle size distribution, color change, and stability of lily juice under different ultrasonic treatment conditions (152 W, 304 W, 456 W, 608 W, and 760 W). The results showed that the lily juice exhibited non-Newtonian shear thinning behavior, and the viscosity decreased with the increase in ultrasonic power. Under ultrasonic treatment conditions, there was no significant change in the pH value and zeta potential value of the samples. The content of cloudy value and total soluble solids (TSS) increased gradually. However, both the sedimentation components and centrifugal sedimentation rate showed a downward trend and an asymptotic behavior. In addition, high-power ultrasound changed the color index (L* value decreased, a* value increased), tissue structure, and particle distribution of the sample, and small particles increased significantly. To sum up, ultrasonic treatment has great potential in improving the physical properties and suspension stability of lily juice.

Factors affecting aroma compounds in orange juice and their sensory perception: A review

Orange juice is the most widely consumed fruit juice globally because of its pleasant aromas and high nutritional value. Aromas, contributed by free and bound aroma compounds, are an important attribute and determine the quality of orange juice and consumer choices. Aldehydes, alcohols, esters, and terpenoids have been shown to play important roles in the aroma quality of orange juice. Many factors affect the aroma compounds in orange juice, such as genetic makeup, maturity, processing, matrix compounds, packaging, and storage. This paper reviews identified aroma compounds in free and bound form, the biosynthetic pathways of aroma-active compounds, and factors affecting aroma from a molecular perspective. This review also outlines the effect of variations in aroma on the sensory profile of orange juice and discusses the sensory perception pathways in human systems. Sensory perception of aromas is affected by aroma variations but also converges with taste perception. This review could provide critical information for further research on the aromas of orange juice and their manipulation during the development of products.

A Novel Strategy to Improve Cloud Stability of Orange-Based Juice: Combination of Natural Pectin Methylesterase Inhibitor and High-Pressure Processing

This study investigated the prospect of producing cloud-stable orange-based juice by combining high-pressure processing (HPP) with a natural kiwifruit pectin methylesterase inhibitor (PMEI) during chilled storage. Kiwifruit is rich in a PMEI, which greatly improves the cloud loss caused by the pectin methylesterase (PME) demethylation of pectin. The results show that the cloud loss of orange juice occurred after 3 days, while the orange-kiwifruit mixed juice and kiwifruit puree were cloud stable during 28 days' storage. Although, the kiwifruit puree contained larger particles compared to the orange juice, its higher viscosity and solid-like behavior were dominant, improving the cloud stability of the juice systems. In addition, the particle size distribution and rheological properties were highly related to PME activity, PMEI activity, and pectin characterization. The kiwifruit PMEI showed higher resistance to HPP and storage time than PME. More water-solubilized pectin fractions with a high molecular mass were found in the kiwifruit puree, leading to its high viscosity and large particle size, but a more chelator-solubilized pectin fraction with a low esterification degree was observed in the orange juice, resulting in its cloud loss. In general, the outcome of this work provides a novel strategy to improve the cloud stability of orange-based juices using natural PMEIs and nonthermal processing technologies.

Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques

As the most widespread juice produced and consumed globally, citrus juice (mandarin juice, orange juice, and grapefruit juice) is appreciated for its attractive and distinct aroma. While the decrease of characteristic aroma-active compounds and the formation of off-flavor compounds are easy to occur in processing and storage conditions. This review provides a comprehensive literature of recent research and discovery on citrus juice off-flavor, primarily focusing on off-flavor compounds induced during processing and storage (i.e., thermal, storage, light, oxygen, package, fruit maturity, diseases, centrifugal pretreatment, and debittering process), formation pathways (i.e., terpene acid-catalyzed hydration, caramelization reaction, Maillard reaction, Strecker degradation, and other oxidative degradation) of the off-flavor compounds, effective inhibitor pathway to off-flavor (i.e., electrical treatments, high pressure processing, microwave processing, ultrasound processing, and chemical treatment), as well as odor assessment techniques based on molecular sensory science. The possible precursors (terpenes, sulfur-containing amino acids, carbohydrates, carotenoids, vitamins, and phenolic acids) of citrus juice off-flavor are listed and are also proposed. This review intends to unravel the regularities of aroma variations and even off-flavor formation of citrus juice during processing and storage. Future aroma analysis techniques will evolve toward a colorimetric sensor array for odor visualization to obtain a "marker" of off-flavor in citrus juice.

Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization

Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.

Structural changes in pH-responsive gelatin/hydroxypropyl methylcellulose phthalate blends aimed at drug-release systems

The present study aimed to investigate the thermal- and pH-dependent gelation behavior of gelatin/HPMCP blends using ultraviolet (UV) spectrophotometry, viscoelasticity, and dynamic light scattering (DLS). We found that the release of lisinopril from gelatin/HPMCP gels can be inhibited at low pH. UV spectrophotometric analysis showed that pH had a significant effect on the transparency of aqueous HPMCP systems and gelatin/HPMCP gels. The viscoelastic patterns of gelatin/HPMCP at pH 4.6 considerably differed from those of gelatin/HPMCP at pH 5.2 and 6.0. DLS measurements showed that HPMCP molecules in low concentrations underwent strong aggregation below pH 4.8. Such HPMCP aggregation induces a physical barrier in the matrix structures of the gelatin/HPMCP gels, which inhibits the drug release at pH 1.2. This hydrogel delivery system using polymer blends of gelatin/HPMCP can be used in oral gel formulations with pH-responsive properties.

Effect of Anchote (Coccinia abyssinica) and Potato Starch Addition on Colloidal Stability of Pineapple Juice

Starch is one of the most important value-added food ingredients used as a thickener in many foods and industrial applications. This research investigated the effect of different concentrations of starch (anchote and potato) addition on the colloidal stability of pineapple juice. The experiment was carried out on a two-factor factorial design arranged in CRD. The first factor (starch type with two levels (anchote and potato)) and the second factor (starch concentration with three levels (1%, 3%, and 5%)) were considered. The starch-added juice samples were preserved for 15 days at room temperature. The physicochemical properties, colloidal stability, microbial counts, and sensory analysis were conducted in a 7-day interval including the first day. The results revealed that different starch concentrations showed a significant effect (P ≤ 0.05) on the cloud stability, most of the physicochemical properties and microbial count of pineapple juice as compared to the control. The turbidity and viscosity of the juice samples were increased significantly (P ≤ 0.05) by the starch addition; in contrast, pulp sedimentation and microbial counts were decreased. As storage duration increased, turbidity, viscosity, TSS, pH, and vitamin C content of juice decreased, whereas sedimentation, TA, and microbial count increased. The results revealed that the total bacterial and fungal counts of pineapple juice samples were rising as storage durations increased. The maximum cloud retention was observed in juice added with 5% anchote starch. Finally, it is confirmed that starch (anchote and potato) addition positively affected the colloidal stability of pineapple juice and also possessed high potential to extend the shelf life.

Concentrated O/W emulsions formulated by binary and ternary mixtures of sodium caseinate, xanthan and guar gums: rheological properties, microstructure, and stability

The effects of xanthan gum (XG) (0, 0.3, 0.6 wt%), guar gum (GG) (0, 0.3, 0.6 wt%) and XG:GG mixtures (0.3-0.3, 0.3-0.6, 0.6-0.3 and 0.6-0.6 wt%) on the physical stability of sodium caseinate (CN) stabilized concentrated O/W emulsions (φoil = 0.6) were examined. The emulsion stability, microstructure, droplets size distribution, and rheological properties were evaluated. The findings showed that with increasing total gum concentration up to 0.6% droplets size and emulsion instability significantly decreased (p < 0.05). The emulsion containing a ternary mixture of CN:XG:GG at total gum concentration (0.6%) with a mixing ratio of 0.3:0.3 XG:GG exhibited the best stability with the highest ESI value (98.3%). Above the critical concentration, an excessive increase in storage modulus led to a significant increase in droplet size and emulsion instability. In brief, concentrated emulsions stabilized by binary and ternary mixtures (CN/XG/GG) may be applicable in special food like heavy cream and as a template for fabricating oleogels.

Physicochemical Properties and Bioactivity of a New Guar Gum-Based Film Incorporated with Citral to Brown Planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

The brown planthopper (BPH), Nilaparvata lugens (Stål), is the most notorious rice insect pest. In order to repel BPH effectively while being environmentally friendly, a new film based on guar gum incorporated with citral (GC film) was formulated. A toxicity bioassay of citral and guar gum at different proportions (ratios of 3:1, 2:1, 1:1, 1:2, and 1:3 in w/w) of GC film-forming emulsion to BPH was performed with the rice stem dipping method. Results showed that the most effective ratio of citral to guar gum was 1:1 with the median lethal concentration (LC₅₀) of 4.30 mg/mL, far below the LC₅₀ of guar gum (GG)/citral individual (141.51 and 44.38 mg/mL, respectively). The mortality of BPH adults and nymphs in the third instar treated with different dilution multiples of GC film-forming emulsion ranged from 46.67% to 82.22% and from 37.78% to 71.11%, respectively. These indicated that GC film-forming emulsion had a direct toxicity on BPH, and the mixture of citral and GG had synergistic interactions. Subsequently, Fourier-transform infrared spectroscopy showed that the incorporation of guar gum with citral was successful and did not result in the formation of new chemical bonds. The GC film exhibited a darker color and rougher surface topography with larger apertures and deeper gullies (Ra = 1.42 nm, Rq = 2.05 nm, and Rmax = 25.40 nm) compared to the guar gum film (GG film) (Ra = 1.00 nm, Rq = 1.33 nm, and Rmax = 16.40 nm), as determined by transmission electron microscopy and atomic force microscopy. The GC film exhibited a 50.4% lower solubility in water (30.30% vs. 15.00%) and 71.3% oxygen permeability (8.26 × 10⁻⁹ vs. 2.37 × 10⁻⁹ cm³/m²·d·Pa) (p < 0.05) but did not demonstrate any significant difference in mechanical properties, such as thickness (39.10 vs. 41.70 mm), tensile strength (41.89 vs. 38.30 N/mm²), and elongation at break (1.82% vs. 2.03%) (p < 0.05) compared to the GG film. Our findings established a link between physicochemical properties and bioactivity, which can provide useful information on developing and improving GC films and may offer an alternative approach for the control of BPH in the near future.

Chemical structure, chain conformation and rheological properties of pectic polysaccharides from soy hulls

We obtained a new acidic soy hull polysaccharide (SHP-1) with a molecular weight (Mw) of 4.81 × 105 g/mol through ammonium oxalate and microwave assisted extraction. SHP-1 was mainly composed of galacturonic acid, galactose, rhamnose and arabinose (molar ratio = 46.59%:17.95%:14.77%:13.97%) with small amounts of fucose, glucose, mannose and xylose. The chemical structure was presumed to be of pectin-I type, consisting of 2/3 HGA and 1/3 RG-I. Furthermore, the rheological information and the chain morphology of SHP-1 were different in five solvents. Surfactant, salt and alkali solutions enhanced the solubility and flexibility of the polysaccharide, but the polysaccharide showed decreased fluidity under acidic conditions. The addition of ions and alkali increased the consistency coefficient of the solution, but the effect was far less than that of the cross-linking morphology. The structural and morphological information of purified SHP should aid in further study of its structure-function relationships and applications.

Mannans: An overview of properties and application in food products

This review aims to emphasize the occurrence and abundant presence of mannans in nature, their classification, structural differences and significance in food and feed industry. With rising demand from the consumers' end for novel natural foods, usage of galactomannan and glucomannan has also increased alternatively. Non toxicity of mannans permits their usage in the pharmaceutical, biomedical, cosmetics, and textile industries. In the food industry, mannans have various applications such as edible films/coating, gel formation, stiffeners, viscosity modifiers, stabilizers, texture improvers, water absorbants, as prebiotics in dairy products and bakery, seasonings, diet foods, coffee whiteners etc. Applications and functions of these commonly used commercially available mannans have therefore, been highlighted. Mannans improve the texture and appeal of food products and provide numerous health benefits like controlling obesity and body weight control, prebiotic benefits, constipation alleviaton, prevent occurrence of diarrhea, check inflammation due to gut related diseases, management of diverticular disease management, balance intestinal microbiota, immune system modulator, reduced risk of colorectal cancer etc. Mannan degrading enzymes are the key enzymes involved in degradation and are useful in various industrial processes such as fruit juice clarification, viscosity reduction of coffee extracts etc. besides facilitating the process steps and improving process quality.