Ohmic heating-assisted water extraction of steviol glycosides and phytochemicals from Stevia rebaudiana leaves

A review on rebaudioside M: The next generation steviol glycoside and noncaloric sweetener

So far, the use of artificial low-calorie sweeteners, like sucralose, saccharin, and so on, to replace the conventional-based sugars has not succeeded due to the long-term adverse health effects, for example, hypertension, and not well-known safety stand. In this review, we discussed the next generation SvGl (rebaudioside M [Reb M]), their biosynthetic pathway in plant, high-yield production via microbial fermentation and enzyme engineering, physicochemical properties, taste modification, kinetic metabolism, application in food and beverages, safety and toxicological evaluation, regulation and dosage recommendation, and health benefits. In stevia, the biosynthesis of stevia glycosides, especially Reb M, is derived from the bifurcation of the pathway leading to gibberellin, followed by subsequent enzymatic modification of rubusoside. Reb M is more economically produced via microbial fermentation of modified yeast Yarrowia lipolytica and enzymatic bioconversion of rebaudioside A (Reb A) or Reb E. Reb M can serve as a suitable alternative to the conventional-based sugars.

Textural, rheological, melting properties, particle size distribution, and NMR relaxometry of cocoa hazelnut spread with inulin-stevia addition as sugar replacer

This study investigated the influence of substituting 60, 80, and 100% of the sugar in traditional cocoa hazelnut paste (control) formulation with inulin-stevia (90:10, w/w) mixture on textural and rheological characteristics, melting behavior, water activity (aw), particle size distribution (PSD), and color. Textural, rheological, melting properties, and color of samples were analyzed after 1, 2, and 3 months of storage at 11°C. Nuclear magnetic resonance (NMR) relaxometry experiments were also performed to understand the interaction of new ingredients with oil. Replacement of sugar with inulin-stevia gave darker color, reduced Casson yield stress, and changed the textural parameters and melting profile of the samples depending on the level but did not create a remarkable effect on PSD and Casson plastic viscosity. Increasing inulin-stevia content yielded lower aw and higher T2a values indicating decreased mobility of water. Complete removal of sugar caused low spreadability. The results showed that an 80% replacement level yielded a product with similar textural parameters and fat-melting mouth feeling compared to control sample. Cocoa hazelnut spreads prepared with inulin and stevia showed good textural stability during storage.

Innovative date syrup processing with ohmic heating technology: Physiochemical characteristics, yield optimization, and sensory attributes

The present study aimed to investigate the application of the ohmic heating (OH) technique in the production of date syrup from the date fruit of the Sukkary variety at different electric field strengths (EFS) (9, 10, and 11 V/cm). The results were compared to the conventional heating method (CH). The response surface methodology was used to optimize yield. The results showed that the time to reach the boiling point of dates and water mixture using OH was less than the CH by 80% for extracting and 900% for evaporation. In addition, the productivity of date syrup using OH at EFS of 11 V/cm was higher than the CH by 86.11%. There is no significant effect between OH at EFS of 11 V/cm and CH in moisture content, refractive index, density, TSS, and viscosity. The optimum level of EFS was 11.5 V/cm, which gave a higher yield (64.93%). OH, save consumed power and cost. The OH gave the highest scores of sensory characteristics compared to CH. Total sugars, monosaccharides, and ketone monosaccharides were detected in the date syrup, and the result was positive, while the quintuple sugars and multiple sugars were negative for all treatments. The OH reduced the cost by 85.78% compared with CH.

Comparison of ohmic heating- and microwave-assisted extraction techniques for avocado leaves valorization: Optimization and impact on the phenolic compounds and bioactivities

Avocado tree pruning activities generate a substantial amount of residual biomass, which includes different parts of the plant, such as leaves, twigs, branches, and small fruits. This study aimed to investigate the impact of different green extraction methods of microwave-assisted extraction (MAE) and ohmic heating-assisted extraction (OHAE) for the phenolic extraction of avocado leaves based on a statistical approach, central composite design (CCD), and response surface methodology (RSM). Water was preferred using as an environmentally and health-friendly solvent for both methods. The phenolic composition, antioxidant activity, and antidiabetic potential of the extracts were identified and comparatively assessed. The developed models exhibited a high degree of reliability with optimal conditions for OHAE and MAE, which were determined as 9.38 V/cm voltage gradient, 6 min extraction time, at 60°C, 5 min, and 1 g dried leaf/100 mL water. Epicatechin was identified as the primary phenolic compound in OHAE extracts, while chlorogenic acid was the dominant compound in MAE extracts. The extracts obtained from OHAE and MAE were tested for their ability to inhibit α-glucosidase activity, with IC50 (mg/mL) values of 0.85 and 1.14, respectively. The DPPH radicals scavenging activity (IC50 mg/L) of OHAE and MAE were detected as 2.96 and 3.41, respectively. In conclusion, both methods yielded extracts rich in polyphenols that displayed high antioxidant activity, but OHAE was found to be superior to MAE in terms of TPC, DPPH, and antidiabetic activities. The results of this study have the potential to make significant contributions toward promoting the principles of a circular economy by facilitating the valorization of the avocado pruning waste.

Environmentally Friendly Techniques for the Recovery of Polyphenols from Food By-Products and Their Impact on Polyphenol Oxidase: A Critical Review

Even though food by-products have many negative financial and environmental impacts, they contain a considerable quantity of precious bioactive compounds such as polyphenols. The recovery of these compounds from food wastes could diminish their adverse effects in different aspects. For doing this, various nonthermal and conventional methods are used. Since conventional extraction methods may cause plenty of problems, due to their heat production and extreme need for energy and solvent, many novel technologies such as microwave, ultrasound, cold plasma, pulsed electric field, pressurized liquid, and ohmic heating technology have been regarded as alternatives assisting the extraction process. This paper highlights the competence of mild technologies in the recovery of polyphenols from food by-products, the effect of these technologies on polyphenol oxidase, and the application of the recovered polyphenols in the food industry.