Volume 17, Issue 8

This research focuses on the use of protein-polyphenol complex and protein-polyphenol: polysaccharide complexes to prepare oleogels through an emulsion-templated approach. Electrolysis soy protein isolate (ESPI) could be effectively adsorbed on the surface of a single-layer emulsion to increase the particle size. The order of the negative charges of the emulsion after adding polysaccharides was xanthan gum (XG)> pectin> carboxymethyl cellulose (CMC). Rheological behavior showed that the stability of the double-layer emulsions increased, and the viscoelasticity increased around one order of magnitude with the addition of polysaccharides. The oil binding capacity (OBC) of the oleogel prepared by adding polysaccharides increased to more than 97%. The peroxide value (PV) and anisidine value (AV) of XG oleogel were the minimum values in all samples. The AV and POV were within the regulatory limits of China after storage for 21 days. This provides a reference to design of ESPI-based oleogel for different applications.

There are no standard machines or systems used for grading the new tea leaves in the market, a micro-spiral pneumatic selection system was designed to separate fresh tea leaves, solving the difficulties in tea leaf selecting and separation. The system can flexibly separate the tea leaves continuously in high quality. And the simulation model was established based on the experiments results to optimize the design parameters. The maximum constant air flow rate separation tests showed that the symmetrical distribution effect of six tubular fans provided better balance than four tubular fans, and three grades of fresh tea can be differentially sorted. Additionally, solid particle simulation tests showed that separation begins at heights between 0.27 and 0.37 m. When the air flow rates range from 4.4 to 6.6 m/s, fresh tea leaves containing only one leaf per stem are well separated from multi-leaf containing stems. Furthermore, solid particle simulation tests indicated that different sizes of fresh tea leaves can be distributed in corresponding annular regions of specific widths; therefore, the flow field simulation tests showed that an optimized system could separate tea leaves according to the number of leaves on the stem. To sum, this study reported a novel micro-spiral pneumatic selection system with high efficiency for the separation of fresh tea leaves.

A protein isolate from passion fruit seeds (PFSPI) obtained by alkaline extraction and isoelectric precipitation was treated with sonication for 15 and 30 min at 40 kHz to evaluate its impact on the physicochemical and functional properties. The PFSPI had a purity of 96.21% protein, with albumins being the main fraction (75.66%). Ultrasound increased the bulk density ( ρ ) of PFSPI by 13.3% and the formation a more porous structure by a greater separation between particles. Protein solubility of PFSPI in the range of pH 2–12 sonicated for 15 and 30 min, increased on average 5.21 and 9.86%, respectively, in comparison with the control. PFSPI foaming properties were influenced by pH and sonication time, achieving up to 577%, while the minimum gelling concentration was reduced from 4 to 2% at pH 7. Therefore, sonication treatment improved some functional properties of PFSPI for its potential use as a food ingredient.

In this study, chiffon cakes were fortified with potato flakes and raw dehydrated potato flour (RDPF) prepared by freeze-drying and hot air drying. The dough’s rheological properties demonstrate that potato flakes are unsuitable for making chiffon cakes, especially at percentages of 30 and 50%. Adding RDPFs decreased the dough height and adhesiveness but increased the hardness slightly compared with the control. Supplementing with potato flakes has the most influence on cake textural properties, especially at percentages of 30 and 50%, which correspondingly reduces the sensory evaluation score. All the RDPF cake formulations exhibited higher comprehensive nutritional value in terms of protein, fat, dietary fiber, minerals, and amino acids. The cake formulations containing RDPF obtained by hot air drying contained the lowest carbohydrate contents.

In this research, sodium alginate (ALG) microgels were prepared with different ALG concentrations, and physicochemical and emulsifying profiles of these hydrophilic microgels were comparatively analyzed. Results showed that these microgels possessed different size, hardness, and surface charge. All these microgels could stabilize an oil-in-water emulsion through the Mickering mechanisms, and smaller microgels had better emulsifying capacity. The surface hydrophobicity and interfacial tension of the microgels had no exact effects on their emulsifying behaviors. Compared with the harder microgels (prepared with high ALG concentration, e. g. 4 mg/mL), the emulsifying capacities of the softer ones (prepared with low ALG concentration, e.g. 1 mg/mL) were more sensitive to the high salt concentration (200 mM NaCl) but stable under acidic environment (pH 2.0). Our research would afford a new strategy for the manufacture and application of the novel polysaccharide-based emulsifiers.

The objective of this work is to extract phenolic compounds from Punica granatum L. peel and to optimize the process variables. In this study, extraction was carried out using soxhlet, solvent and ultrasound-assisted extraction. Soxhlet extraction of phenolic compounds were reported as 87.31 mg GAE/g dW TPC, 70.30 mg RUE/g dW TFC and 98.68 mg CE/g dW TAC. Solvent extraction found 56.99 mg GAE/g dW, 42.93 mg RUE/g dW and 64.13 mg CE/g dW, while for ultrasonic-assisted extraction it was 77.23 mg GAE/g dW, 62.55 mg RUE/g dW and 91.40 mg CE/g dW of total phenolic content, total flavonoid content and total amount of anthocyanin content, respectively. The presence of phytochemicals was identified using GC-MS and it was found that the extracts contained high amount of trans -13-Octadecenoic acid which is a cancer preventive compound. Scanning electron microscope analysis was used to study the effect of ultrasound on the surface of the sample and understand the morphological changes.

Radio frequency (RF) sterilization of low-moisture, high-oil, high-protein, and viscous sauces for instant food (LHHVS) demonstrates many advantages, but uneven heating is a main problem that must be addressed. Main factors that affect heating uniformity are generally considered dielectric properties, shape and size of the sample and its position relative to the electrode plate, in addition the structure and voltage of RF electrode. A method based on texture characteristics of the solid–gel–liquid mixing system of LHHVS for adjustment and control of energy distribution in the RF field is proposed in this study to improve the heating uniformity. First, energy conversion principles and control equations of RF heating were analyzed on the basis of dielectric theory. Second, the influence of RF electromagnetic field-medium polyetherimide (PEI) on the RF heating of peanut butter (RHPB) was investigated on the basis of the numerical model of RHPB that was verified through experiments. Finally, the influence mechanism and its regulation and control effect were analyzed and discussed. The following conclusions can be drawn from this study: the increase of electrode gaps exerts minimal effect although it reduces the unevenness of the energy distribution. However, RF heating protocols must use the smallest possible electrode gap to heat agrifoods and increase the heating rate significantly. The energy distribution on the part of the sample close to PEI varies with the change of geometry and size of PEI when its placement is bias or symmetric. The area of energy enhancement continues to expand where the sample is in contact with PEI as PEI gradually increases. The area where the temperature increases under the influence of PEI will expand along the direction of the sample radius when the thickness of PEI remains unchanged and the radius gradually enlarges; otherwise, it will expand along the direction of the sample thickness. The influence of PEI on the energy distribution of RHPB demonstrates local characteristics. PEI significantly influences the energy distribution and heating mode of RHPB, which is easy to adjust and control, but does not reduce the processing speed and does not increases energy consumption. Hence, PEI is an effective means to interfere with energy distribution of RHPB. Uniform energy distribution can be obtained by selecting the appropriate PEI shape and size. Results of this study can help determine the experimental protocol for RHPB with the optimal uniform distribution and promote the fast commercial application of this technology.