Physicochemical properties and anthocyanin bioaccessibility of downy rose-myrtle powder prepared by superfine grinding

Myrtle: a versatile medicinal plant

Myrtus, commonly called myrtle, is a genus of flowering plants in the Myrtaceae family. This study aimed to review myrtle's pharmaceutical, food, and other uses. The pharmacological effects of myrtle for antioxidant, antibacterial, and anti-inflammatory activities, reduction of COVID-19 symptoms, anti-diabetic in the animal model, hepatoprotective in the rat model, antihypertensive, control of intestinal helminthiasis in mice model, inhibition of glucosyltransferase activity, protective effect on oxidative metabolism in the hypothyroidism model, and reducing the damage caused by skin burns are reviewed. In addition, the food uses of this plant such as improving the oxidative and microbial stability of products containing salmon, antimicrobial activity in meat and dairy products, flavoring in sea salt, microbial improvement of fresh fruits during post-harvest storage, animal nutrition, and bio-oil production are summarized.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41110-023-00194-y.

The Effect of Vibratory Grinding Time on Moisture Sorption, Particle Size Distribution, and Phenolic Bioaccessibility of Carob Powder

Carob pod powder, an excellent source of health-promoting substances, has found its use in a wide range of food products. Grinding conditions affect the physical and chemical properties of the powder, but their influence on the bioaccessibility of phenolic compounds in carob pod powder has not yet been determined. The carob pods were ground for 30-180 s in a vibratory grinder. The median values (D₅₀) of particle size decreased after 60 s of grinding (87.9 μm), then increased to 135.1 μm. Lightness showed a negative correlation with D₅₀ and a_w, while the values of redness and yellowness decreased with the reduction in particle size and water activity. The smaller the value of D₅₀, the higher the equilibrium moisture content of carob powder. Phenolic acids (vanillic, ferulic, cinnamic) and flavonoids (luteolin, naringenin, apigenin) were found in all samples of carob powder. The grinding time influenced their content in carob powder, with maximum values at 180 s. Similar observations were made when assessing antioxidant capacity. The in vitro digestion process only improved the bioaccessibility of catechin content in all samples. However, the bioaccessibility of the phenolic compounds and the total phenolic and flavonoid contents decreased with the increase in grinding time. Our findings revealed that the grinding of carob pods for 180 s improved the extractability of phenolics; however, their bioaccessibility was reduced. It is sufficient to ground the carob pod for 30 s, ensuring good availability of nutraceuticals and lower energy cost for grinding.

Effects of superfine grinding on the physicochemical properties, antioxidant capacity, and hygroscopicity of Rosa rugosa cv. Plena powders

BACKGROUND

Rosa rugosa cv. Plena (RP) is a commercially significant crop with edible flowers. Due to its high medicinal and nutritional value, it has recently attracted increasing attention in the food industry. In this study, the physicochemical properties, antioxidant capacity, and hygroscopicity of four RP powders produced by ball milling were compared.

RESULTS

The brightness, redness, and blueness of RP powders improved after superfine grinding. The water and oil holding capacity decreased with a reduction in the particle size but the water solubility index increased from 7.10% to 29.93%. The elements present in the powders were not significantly (P > 0.05) affected by particle size while phytochemicals were released and extracted more easily after superfine grinding, resulting in higher anthocyanin, polyphenol, and flavonoid content (3.06, 34.01, and 3.97 mg g^-1 , respectively), and stronger antioxidant capacity than was found with other powders (ABTS (2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activities were 24.51 and 39.81 mM trolox equivalents (TE) g^-1 , respectively). Superfine grinding also improved the water-absorption capacity of RP powders under a high-RH environment.

CONCLUSION

Superfine grinding is a promising technique for the production of RP powders with stronger bioactive substances and bioactivity. © 2022 Society of Chemical Industry.

Roles of Drying, Size Reduction, and Blanching in Sustainable Extraction of Phenolics from Olive Leaves

It is now known that olive leaves contain a sizable portion of polyphenols and there is much research highlighting that these natural ingredients favorably exhibit bio-functional activities. In this regard, many studies have focused on the exploration of optimum conditions involved directly in the extraction process. These investigations, while being highly valuable, may somewhat cast a shadow over other contributing factors such as those involved in the preprocessing of leaves, including size reduction, drying, and blanching. The use of these unit operations under appropriate conditions, together with other benefits, potentially exert improved surface area, homogeneity, and diffusion/mass transfer which may help develop the liberation of target bio-compounds. The research work in this area, particularly size reduction, is relatively limited. Although in various experiments they are incorporated, not many studies have focused on them as the main predictor variables. The performance of further research may help ascertain the magnitude of their effects. Consideration of the operational parameters in preprocessing step is equally important as those in the processing/extraction step that may comparably influence on the extraction efficiency. This review provides an overview of the potential roles of drying, size reduction, and blanching in the extraction efficiency of phenolics from olive leaves.

Micronization increases the bioaccessibility of polyphenols from granulometrically separated olive pomace fractions

The effect of micronization of granulometrically fractionated olive pomace (OP) on the bioaccessibility of polyphenols and the antioxidant capacity was investigated during sequential in vitro static digestion. Crude OP was fractionated in a 2-mm sieve (F1: > 2 mm; F2: < 2 mm) and then micronized (300 r min^-1, 5 h) generating F1AG (17.8 μm) and F2AG (15.6 μm). Micronization increased the release of hydroxytyrosol, oleuropein, caffeic acid, and decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA) in the salivary and gastric phase, beyond luteolin in the gastric phase. Micronization also increased the intestinal bioaccessibility of hydroxytyrosol, 3,4-DHPEA-EDA, oleuropein, luteolin, and apigenin; it was more effective for F2AG than F1AG. Micronized samples increased antioxidant capacity in the gastric phase. F2AG exhibited the highest antioxidant capacity in the insoluble intestinal fraction. Thus, micronization can be further exploited to improve the nutraceutical properties of OP by increasing the bioaccessibility and antioxidant capacity of phenolic compounds.