Investigation on the phenolic composition, related oxidation and antioxidant activity of thinned peach dried by different methods

Yacon powder mix: Effects of the composition and the process of microencapsulation by spray drying

Yacon is a tuber known as a healthy food due to its effects as an antidiabetic, anti-inflammatory, anticancer, and prebiotic agent; it is rich in fructooligosaccharides (FOS) and antioxidants, and due to its sweet taste and low-calorie content, it is used as a substitute for ordinary sugar. This research aimed to evaluate the influence of the composition of the feed and the microencapsulation process by spray drying (SD) on the properties of a yacon powder mixture (YP). Response surface methodology with a central composite design with a face-centered composition (α = 1) was used, considering the independent variables: inulin (IN) (3-5% w/w), maltodextrin (MD) (3-5% w/w), air inlet temperature (AIT) (140-160 °C), air outlet temperature (AOT) (75-85 °C) and atomizer disc speed (ADS) (18000-22000 rpm), and the dependent variables: moisture (Xw), water activity (aw), hygroscopicity (Hy), solubility (S), particle size (percentile D10, D50, and D90), total phenols (TP), antioxidant capacity (ABTS and DPPH), color (CIE-Lab*) and yield (Yi). The suspension formulation contained xanthan gum (0.167 %) and a mixture of ascorbic and citric acids (0.3 %). The aw and Xw values of the YP guarantee its microbiological stability; however, the process formulation produces a complex matrix (FOS- sugars- MD - IN) with high affinity for water, which favors adsorption phenomena (hygroscopic material) and high reconstitution (high solubility). The independent variables that best fit the experimental optimization criteria were: IN = 3.0 %, MD = 5.0 %, AIT = 143.7 °C, AOT = 80.1 °C, ADS = 22000 rpm, where Yi = 84.2 %, and the quality of the YP: Xw = 2.4 %, a w  = 0.220, Hy = 23.0 %, S = 96.9 %, D10 = 10.6 μm, D50 = 23.4 μm and D90 = 169.3 μm, TP = 1228.2 mg gallic acid equivalent/100 g, ABTS = 2295.9 mg Trolox equivalent (TE)/100 g, DPPH = 5192.3 mg TE/100 g, L* = 80.5, a* = 5.1 and b* = 17.4. SD is an effective technology that positively impacts the development of new food products. In addition, the YP could have multipurpose applications for the industry, generating value in this agri-chain.

From polyphenol to o-quinone: Occurrence, significance, and intervention strategies in foods and health implications

Polyphenol oxidation is a chemical process impairing food freshness and other desirable qualities, which has become a serious problem in fruit and vegetable processing industry. It is crucial to understand the mechanisms involved in these detrimental alterations. o-Quinones are primarily generated by polyphenols with di/tri-phenolic groups through enzymatic oxidation and/or auto-oxidation. They are highly reactive species, which not only readily suffer the attack by nucleophiles but also powerfully oxidize other molecules presenting lower redox potentials via electron transfer reactions. These reactions and subsequent complicated reactions are capable of initiating quality losses in foods, such as browning, aroma loss, and nutritional decline. To attenuate these adverse influences, a variety of technologies have emerged to restrain polyphenol oxidation via governing different factors, especially polyphenol oxidases and oxygen. Despite tremendous efforts devoted, to date, the loss of food quality caused by quinones has remained a great challenge in the food processing industry. Furthermore, o-quinones are responsible for the chemopreventive effects and/or toxicity of the parent catechols on human health, the mechanisms by which are quite complex. Herein, this review focuses on the generation and reactivity of o-quinones, attempting to clarify mechanisms involved in the quality deterioration of foods and health implications for humans. Potential innovative inhibitors and technologies are also presented to intervene in o-quinone formation and subsequent reactions. In future, the feasibility of these inhibitory strategies should be evaluated, and further exploration on biological targets of o-quinones is of great necessity.

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

The effect of gallic acid alkyl esters and their combination with monoacylglycerol (MAG) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on the formation of hydroperoxides and hexanal were determined during the oxidation of stripped soybean oil. Interfacial tension, water content, and droplet size were evaluated to monitor the physical properties of the oil system. Adding MAG and DOPC, especially MAG/DOPC, to the oil promoted the partitioning of antioxidants into the water-oil interfaces by further reducing the interfacial tension. The stripped oil containing methyl gallate (MG) accompanied by MAG/DOPC had lower values of the critical micelle concentration of hydroperoxides and larger micellar size at the induction period. This confirms that MG was able to more effectively reduce the free hydroperoxides concentration and inhibit them in an interfacial way. The conjunction of surfactants has been shown as a promising strategy to improve the interfacial and antioxidant activity of gallates in the oxidative stability of soybean oil.

Flavor Characterization of Native Xinjiang Flat Peaches Based on Constructing Aroma Fingerprinting and Stoichiometry Analysis

The flat peach is a high economic value table fruit possessing excellent quality and a unique aroma. This article investigated the quality characteristics and aroma fingerprinting of flat peaches (Qingpan, QP; Ruipan 2, R2; Ruipan 4, R4; Wanpan, WP) from Xinjiang in terms of taste, antioxidant capacity, and volatile aroma compounds using high-performance liquid chromatography (HPLC) and HS-SPME-GC-MS. The results showed that the flat peaches had a good taste and high antioxidant capacity, mainly due to the high sugar-low acid property and high levels of phenolic compounds. This study found that sucrose (63.86~73.86%) was the main sugar, and malic acid (5.93~14.96%) and quinic acid (5.25~15.01%) were the main organic acids. Furthermore, chlorogenic acid (main phenolic compound), epicatechin, rutin, catechin, proanthocyanidin B1, and neochlorogenic acid were positively related to the antioxidant activity of flat peaches. All flat peaches had similar aroma characteristics and were rich in aromatic content. Aldehydes (especially benzaldehyde and 2-hexenal) and esters were the main volatile compounds. The aroma fingerprinting of flat peaches consisted of hexanal, 2-hexenal, nonanal, decanal, benzaldehyde, 2,4-decadienal, dihydro-β-ionone, 6-pentylpyran-2-one, 2-hexenyl acetate, ethyl caprylate, γ-decalactone, and theaspirane, with a "peach-like", "fruit", and "coconut-like" aroma. Among them, 2,4-decadienal, 2-hexenyl acetate, and theaspirane were the characteristic aroma compounds of flat peaches. The results provide a theoretical basis for the industrial application of the special aroma of flat peaches.

Controlled Atmosphere Improves the Quality, Antioxidant Activity and Phenolic Content of Yellow Peach during the Shelf Life

Controlled atmosphere (CA) has been demonstrated to maintain the shelf-life quality of fruits, but its effect on the antioxidant activities and phenolic content of yellow peach is not comprehensive. This study analyzed the role of CA on the quality of shelf period, phenolic content and antioxidant activity of "Jinxiu" yellow peach. Yellow peach was left under specific aeration conditions (3.5-4% CO2, 2-3% O2, 92-95.5% N2, 1 ± 0.5 °C) and the control (1 ± 0.5 °C) for 21 d, to observe changes in physiological parameters of the fruit during 10 d of the shelf life (25 ± 1 °C). The result showed that CA reduced the weight loss rate (WLR), decay rate (DR), and browning index (BI) of yellow peaches. Furthermore, the CA held a high level of total flavonoid content (TFC), total phenol content (TPC) and phenolic content in the fruit. Antioxidant analysis showed that polyphenol oxidase (PPO) enzyme activity was lower and free radical scavenging capacity (DPPH, ABTS, and FRAP) and antioxidant enzyme activities (POD and PAL) were higher in the CA group. Combining the results of significance analysis, correlation analysis, principal component analysis (PCA) and hierarchical cluster analysis (HCA) clearly identified the differences between the CA group and the control group. The results showed that the CA could maintain higher phenolic content and reduce the oxidation of yellow peach fruit and enhance fruit quality by affecting the antioxidant activities of yellow peach.

Neuroprotective Potential of Thinned Peaches Extracts Obtained by Pressurized Liquid Extraction after Different Drying Processes

Genetic, environmental and nutritional factors are suggested as primary factors of Alzheimer’s disease (AD), and secondary metabolites such as polyphenols present in thinned peaches are considered as good candidates for AD prevention. Thinned peaches are usually dried to avoid putrefaction, but the effects of the drying method and the extraction process on the polyphenol composition and the neuroprotective potential have never been addressed. In this work, a pressurized liquid extraction (PLE) method was optimized and applied to thinned peaches dried under different conditions, and their neuroprotective potential was evaluated in vitro. In addition, the PLE extracts were characterized via HPLC-Q-TOF-MS/MS, and a permeability assay was performed to evaluate the ability of the identified metabolites to cross the blood–brain barrier (BBB). The PLE extracts obtained from freeze-dried (FD) samples with 50% ethanol in water at 180 °C showed the best neuroprotective potential. Finally, among the 81 metabolites identified, isoferulic acid, 4-methyldaphnetin, coniferyl aldehyde and 3,4-dihydroxyacetophenone were found at higher concentrations in FD extracts. These metabolites are able to cross the BBB and are positively correlated with the neuroprotective potential, suggesting FD together with PLE extraction as the best combination to exploit the neuroprotective capacity of thinned peaches.

Effects of Hot Air Drying on Drying Kinetics and Anthocyanin Degradation of Blood-Flesh Peach

The purpose of this study was to explore the drying kinetics, effective moisture diffusivity, activation energy, color variation, and the thermal degradation properties of anthocyanins of blood-flesh peach under hot air drying for the first time. The results showed that the hot air-drying process of blood-flesh peach belongs to reduced-speed drying. The Page model could accurately predict the change of moisture ratio of blood-flesh peach. The effective moisture diffusivity during hot air drying of blood-flesh peach was in the range between 1.62 × 10⁻¹⁰ and 2.84 × 10⁻¹⁰ m²/s, and the activation energy was 25.90 kJ/mol. Fresh samples had the highest content (44.61 ± 4.76 mg/100 g) of total monomeric anthocyanins, and it decreased with the increase of drying temperature. Cyanidin-3-O-glucoside and delphinidin-3-O-galactoside were the main anthocyanins of blood-flesh peach as identified and quantified by UPLC-QqQ-MS. Interestingly, during the drying process, the content of cyanidin-3-O-glucoside increased at the beginning, and then decreased. However, the content of delphinidin-3-O-galactoside kept decreasing during the whole drying process. Considering the drying efficiency, fruit color and quality, 70 °C would be a suitable temperature for drying blood-flesh peach. This research will provide beneficial information for understanding the anthocyanin degradation of blood-flesh peach during drying, and guide the production of high-quality dried products.

Influence of sequential exogenous pretreatment and contact ultrasound-assisted air drying on the metabolic pathway of glucoraphanin in broccoli florets

In this investigation, the combinations of exogenous pretreatment (melatonin or vitamin C) and contact ultrasound-assisted air drying were utilized to dry broccoli florets. To understand the influences of the studied dehydration methods on the conversion of glucoraphanin to bioactive sulforaphane in broccoli, various components (like glucoraphanin, sulforaphane, myrosinase, etc.) and factors (temperature and moisture) involved in the metabolism pathway were analyzed. The results showed that compared with direct air drying, the sequential exogenous pretreatment and contact ultrasound drying shortened the drying time by 19.0-22.7%. Meanwhile, contact sonication could promote the degradation of glucoraphanin. Both melatonin pretreatment and vitamin C pretreatment showed protective effects on the sulforaphane content and myrosinase activity during the subsequent drying process. At the end of drying, the sulforaphane content in samples dehydrated by the sequential melatonin (or vitamin C) pretreatment and ultrasound-intensified drying was 14.4% (or 26.5%) higher than only air-dried samples. The correlation analysis revealed that the exogenous pretreatment or ultrasound could affect the enzymatic degradation of glucoraphanin and the generation of sulforaphane through weakening the connections of sulforaphane-myrosinase, sulforaphane-VC, and VC-myrosinase. Overall, the reported results can enrich the biochemistry knowledge about the transformation of glucoraphanin to sulforaphane in cruciferous vegetables during drying, and the combined VC/melatonin pretreatment and ultrasound drying is conducive to protect bioactive sulforaphane in dehydrated broccoli.

Lab Scale Extracted Conditions of Polyphenols from Thinned Peach Fruit Have Antioxidant, Hypoglycemic, and Hypolipidemic Properties

Thinned peach polyphenols (TPPs) were extracted by ultrasonic disruption and purified using macroporous resin. Optimized extraction conditions resulted in a TPPs yield of 1.59 ± 0.02 mg GAE/g FW, and optimized purification conditions resulted in a purity of 43.86% with NKA-9 resin. TPPs composition was analyzed by UPLC-ESI-QTOF-MS/MS; chlorogenic acid, catechin, and neochlorogenic acid were the most abundant compounds in thinned peaches. Purified TPPs exhibited scavenging activity on DPPH, ABTS, hydroxyl radical, and FRAP. TPPs inhibited α-amylase and α-glucosidase by competitive and noncompetitive reversible inhibition, respectively. TPPs also exhibited a higher binding capacity for bile acids than cholestyramine. In summary, TPPs from thinned peaches are potentially valuable because of their high antioxidant, hypoglycemic, and hypolipidemic capacities, and present a new incentive for the comprehensive utilization of thinned peach fruit.