A new approach to enhance quinoa protein nano-aggregates: Combined pH shifting - High pressure homogenization.

The physicochemical characteristics of soluble nano-sized quinoa protein isolates prepared by combined pH shifting and high-pressure homogenization were studied. Commercial quinoa protein isolates were exposed to pH shifting at acidic (pH 2-6) or alkaline (pH 8-12) conditions followed by high-pressure homogenization earlier than neutralizing of pH to 7.0. The pH method under pH 12 followed by high-pressure homogenization was found as the most efficient treatment in the reduction of protein aggregate sizes and transparency, improving soluble protein content and surface hydrophobicity. Quinoa protein isolates treated with pH 12 and high-pressure homogenization increased the solubility from 7.85% to 78.97%, creating quinoa protein isolate nanoaggregates with an average size around 54 nm. The quinoa isolate aggregates were used to produce oil-in-water nanoemulsions, which demonstrated the good stability for 14 d at 4 °C. This new approach might present an effective technique for the modification of functional features of quinoa protein isolates.

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.

Comparative analysis of antibrowning agents, hot water and high-intensity ultrasound treatments to maintain the quality of fresh-cut mangoes.

The effect of high-intensity ultrasound (HIU), antibrowning agents (C6H806 & CaCl2), and hot water bath (65 °C) treatments on the prevention of enzymatic browning and 2 weeks shelf-life study of fresh-cut mango fruit slices were evaluated. Results showed that HIU treated mangoes have the lowest PPO activity ranging from 76.17 U/mL to 134.12 U/mL, while improved sensorial properties including decay and off-odor, and enhanced bioactive compounds (ascorbic acid, antioxidant capacity and total phenolics) during storage (4 °C). It is stated that HIU treatment as a promising alternative to replace chemical and/or physical methods to prolong the shelf-life and pursue the quality properties in mango fruit during cold storage.

Comparison of high temperature-short time and sonication on selected parameters of strawberry juice during room temperature storage.

The purpose of current research was to explore the effect of high temperature-short time (HTST) and different ultrasound times intervals on the strawberry juice for a period of 14 days. Strawberry fruits were treated at 72 °C for 15 s by HTST and also sonicated at 20 kHz and 100% amplitude for 5, 10, and 15 min. The main objective is to evaluate the effect of treatments and storage time on color, total antioxidants, total phenolics, ascorbic acid and microbial content of strawberry juice. Results showed that the increase in the sonication treatment time (from 5 to 15 min) showed a higher total phenolics, antioxidant capacity and ascorbic acid content. In addition, 15 min sonicated-strawberry juices showed a higher lightness values as compared to HTST treated strawberry juice. Sonication treatment showed a potential as a method to preserve and improve the phytochemical quality of strawberry juice during room temperature storage.

Ultrasonic Cutting as a New Method to Produce Fresh-Cut Red Delicious and Golden Delicious Apples.

The fresh-cut or sliced apple market has grown rapidly in recent years due to consumers' demand for fresh, convenient, and nutritious foods. Fresh-cut apples also contributed to increased consumption of fruits among school children. However, not many studies have investigated means to improve the quality of fresh-cut apples. In this study, we explored the use of ultrasound as a new method to cut apples and examined the quality of two apple varieties (Red Delicious and Golden Delicious) cut with ultrasound. Both apple types were cut without (control) and with ultrasound at four amplitudes (0%, 30%, 40%, and 50%) with an ultrasonic knife. Quality attributes, for example, color, pH, polyphenol oxidase (PPO) activity, surface morphology, and sensory characteristics (color, odor, overall acceptability, and off-odor) of the apples right after cutting and during a 2-week storage at refrigeration temperature were compared. With the set up used in this study, both apples cut with ultrasound exhibited a relatively dense and smooth surface morphology with less cell damage compared with the relatively rough surface and more cells damage in the control. An improvement in quality attributes was observed when the ultrasound amplitude was increased from 30% to 50%. The apples cut with ultrasound had a lower PPO activity compared to the control, indicating less browning. In visual quality evaluation, panelists showed higher liking of the apples cut with ultrasound. The ultrasound-assisted cutting has showed promise for producing fresh-cut apples with improved quality, and may be used as an alternative to traditional cutting method. PRACTICAL APPLICATION: Fresh-cut produce has gained popularity in recent years due to its health benefits. Traditional methods to produce fresh produce use a static stainless steel blade to cut fruits or vegetables, causing chemical or visual quality issues. This study proposed a new method using a blade that vibrates at ultrasonic frequency to cut apples. The results have shown an improvement in the quality of fresh-cut apples. This method may provide a new solution for producing fresh-cut produce to better meet the requirement of consumers for quality products.

Microencapsulation of docosahexaenoic acid (DHA) with four wall materials including pea protein-modified starch complex.

Omega-3 fatty acids, specifically docosahexaenoic acid (DHA, 22 carbons and 6 double bonds) are fundamental compounds for a healthy diet. However, due to their unsaturated nature, omega fatty acid-rich oils are chemically unstable and susceptible to oxidative deterioration. The oxidation results in production of free radicals and unpleasant tastes, negatively impacting the shelf-life, sensory properties, and acceptability of food products. This study was conducted to examine the effect of wall materials on protection of DHA in canola oil against oxidation. A total of 4 wall materials including pea protein isolate (PPI), pea protein isolate - modified starch complex (PPI-MS), Tween 20, and SDS were used for microemulsion preparation with canola oil containing DHA. The freeze-dried powders were analyzed with respect to physicochemical characteristics, oxidative stability, and release properties. The results showed that the PPI-MS as a natural polymeric wall material exhibited similar or better encapsulation efficiency and acceptable level of peroxide value compared to the synthetic surfactants (Tween 20 and SDS). The utilization of protein-polysaccharide complexes enabled the incorporation of specific properties of each biopolymer to further improve emulsion stability for the production of capsules with improved oxidative stability.

Functionalizing soy protein nano-aggregates with pH-shifting and mano-thermo-sonication.

Plant protein-mediated nano-delivery systems have gained increasing attention in the food and pharmaceutical industries in recent years. Several physical and chemical methods for improving the functional properties of plant proteins with respect to the native forms have been proposed. This study presents a new approach, which combines pH-shifting and mano-thermo-sonication (MTS) to produce soy protein nano-aggregates with significantly improved functional properties. Soy-protein isolate (SPI) was treated with pH-shifting at pH 12 or in combination with MTS and high-pressure homogenization (HPH). Response Surface Methodology was used to find the optimal conditions (50°C, 200kPa, and 60s) for the MTS. The combination of pH-shifting and MTS resulted in spherical SPI aggregates of the smallest size, 27.1±1nm, as shown by transmission electron microscopy. The SPI nanoaggregates were used to prepare oil-in-water nanoemulsions with canola oil, which exhibited good stability over 21days at 4°C. In addition, the pH 12-MTS samples had resulted in the highest protein solubility, lowest turbidity, free sulfhydryl and disulfide bonds, surface hydrophobicity, antioxidant activity, and rheological and emulsifying properties than the other samples.