Effects of storage conditions and heat treatment on the hesperidin concentration in Newhall navel orange (Citrus sinensis Osbeck cv. Newhall) juice

Evaluating the Nutritional Composition of Unripe Citrus and Its Effect on Inhibiting Adipogenesis and Adipocyte Differentiation

Citrus fruits offer a range of health benefits due to their rich nutritional profile, including vitamin C, flavonoids, carotenoids, and fiber. It is known that unripe citrus has higher levels of vitamin C, dietary fiber, polyphenols, and flavonoids compared to mature fruits. In this study, we assessed the nutritional components of unripe citrus peel and pressed juices, as well as their anti-obesity potential through the modulation of adipocyte differentiation and the expression of adipogenesis-related genes, specifically PPARγ and C/EBPα, in 3T3-L1 preadipocytes. Our analysis revealed that unripe citrus peel exhibited elevated levels of fiber and protein compared to pressed juice, with markedly low levels of free sugar, particularly sucrose. The content of hesperidin, a representative flavonoid in citrus fruits, was 3,157.6 mg/kg in unripe citrus peel and 455.5 mg/kg in pressed juice, indicating that it was approximately seven times higher in unripe citrus peel compared to pressed juice. Moreover, we observed that the peel had a dose-dependently inhibitory effect on adipocyte differentiation, which was linked to a significant downregulation of adipogenesis-related gene expression. Thus, our findings suggest that unripe citrus possesses anti-obesity effects by impeding adipogenesis and adipocyte differentiation, with the peel demonstrating a more pronounced effect compared to pressed juice.

Comparative Evaluation of Secondary Metabolite Chemodiversity of Citrus Genebank Collection in Greece: Can the Peel be More than Waste?

Citrus fruits are among the most economically important crops in the world. In the global market, the Citrus peel is often considered a byproduct but substitutes an important phenotypic characteristic of the fruit and a valuable source of essential oils, flavonoids, carotenoids, and phenolic acids with variable concentrations. The Mediterranean basin is a particularly dense area of autochthonous genotypes of Citrus that are known for being a source of healthy foods, which can be repertoires of valuable genes for molecular breeding with the focus on plant resistance and quality improvement. The scope of this study was to characterize and compare the main phenotypic parameters (i.e., peel thickness, fruit volume, and area) and levels of bioactive compounds in the peel of fruits from the local germplasm of Citrus in Greece, to assess their chemodiversity regarding their polyphenolic, volatile, and carotenoid profiles. A targeted liquid chromatographic approach revealed hesperidin, tangeretin, narirutin, eriocitrin, and quercetin glycosides as the major polyphenolic compounds identified in orange, lemon, and mandarin peels. The content of tangeretin and narirutin followed the tendency mandarin > orange > lemon. Eriocitrin was a predominant metabolite of lemon peel, following its identification in lower amounts in mandarin and at least in the orange peel. For these citrus-specific metabolites, high intra- but also interspecies chemodiversity was monitored. Significant diversity was found in the essential oil content, which varied between 1.2 and 3% in orange, 0.2 and 1.4% in mandarin, and 0.9 and 1.9% in lemon peel. Limonene was the predominant compound in all Citrus species peel essential oils, ranging between 88 and 93% among the orange, 64 and 93% in mandarin, and 55 and 63% in lemon cultivars. Carotenoid analysis revealed different compositions among the Citrus species and accessions studied, with β-cryptoxanthin being the most predominant metabolite. This large-scale metabolic investigation will enhance the knowledge of Citrus peel secondary metabolite chemodiversity supported by the ample availability of Citrus genetic resources to further expand their exploitation in future breeding programs and potential applications in the global functional food and pharmaceutical industries.

Influence of Hesperidin on the Physico-Chemical, Microbiological and Sensory Characteristics of Frozen Yogurt

Frozen yogurts contain yogurt culture bacteria, which might impart health benefits to their consumers. Global frozen yogurt market sales are expected to grow by 4.8% by 2028, which represents an important opportunity for the industry, consumers and researchers. Polyphenols are metabolites found in plants which have antioxidant and anti-inflammatory properties and might prevent chronic diseases such as cancer, diabetes and cardiovascular diseases. The objective of this study was to elucidate the effect of the polyphenol hesperidin on the physico-chemical, microbiological and sensory characteristics of frozen yogurts. Hesperidin was incorporated into frozen yogurt at three concentrations (125, 250 and 500 mg/90 g of product), while yogurt with no hesperidin was used as a control. The viscosity and overrun of the frozen yogurt were analyzed on day 0. The hardness, pH, color and Lactobacillus bulgaricus and Streptococcus thermophilus counts were determined after 0, 30 and 60 d. The melting rate was determined at 60 and 90 min after 0, 30 and 60 d. The bile and acid tolerances of both S. thermophilus and L. bulgaricus were measured after 7 and 60 d. A hedonic scale of nine points was used to measure sensory attributes. Data were analyzed at α = 0.05 with an ANOVA with Tukey's adjustment, and McNemar's test was used to analyze purchase intent. Hesperidin did not influence the pH, overrun or microbial characteristics. Polyphenol addition compared to the control decreased the melting rate but increased the hardness and bile tolerance of L. bulgaricus, as well as the L* and b* values. The sensory characteristics were not influenced by the lowest concentration of hesperidin, as it was not statistically different from the control. Moreover, consumers were interested in purchasing frozen yogurt with added hesperidin after learning about the health claim. This study can assist in the development of a healthier frozen yogurt in an increasingly competitive market.

Microwave Treatment vs. Conventional Pasteurization: The Effect on Phytochemical and Microbiological Quality for Citrus-Maqui Beverages

This study uncovered the impacts of microwave (MW) treatments compared to conventional pasteurization (TP) on the quality of functional citrus-maqui beverages, with added sucrose or stevia. The influence of these thermal treatments on the microbiological burden and phytochemical composition was determined by processing under two MW power levels (600 W and 800 W) and TP at 85 °C for 15 s for 60 days at room temperature (20 °C). The results indicated that, beyond the microbiological quality achieved in the juices treated by both MW and TP technology, there were no differences among the treatments regarding the stability of vitamin C, anthocyanin, and flavanone concentrations. However, anthocyanins were more stable in those beverages with sucrose added, rendering a better red color. Besides, all treatments ensured microbiological stability throughout the entire storage time. In conclusion, MW treatment could be considered as an alternative to TP, which ensures microbial safety, protecting functional compounds associated with health effects.

Insight into the Inhibitory Mechanisms of Hesperidin on α-Glucosidase through Kinetics, Fluorescence Quenching, and Molecular Docking Studies

The α-glucosidase inhibitor is of interest to researchers due to its association with type-II diabetes treatment by suppressing postprandial hyperglycemia. Hesperidin is a major flavonoid in orange fruit with diverse biological properties. This paper evaluates the effects of hesperidin on α-glucosidase through inhibitory kinetics, fluorescence quenching, and molecular docking methods for the first time. The inhibition kinetic analysis shows that hesperidin reversibly inhibited the α-glucosidase activity with an IC50 value of 18.52 μM and the inhibition was performed in an uncompetitive type. The fluorescence quenching studies indicate that the intrinsic fluorescence of α-glucosidase was quenched via a static quenching process and only one binding site was present between the hesperidin and α-glucosidase. The interaction between them was spontaneous and mainly driven by hydrogen bonds, as well as hydrophobic forces. Furthermore, the molecular docking results suggest that hesperidin might bond to the entrance or outlet part of the active site of α-glucosidase through a network of five hydrogen bonds formed between hesperidin and the four amino acid residues (Trp709, Arg422, Asn424, and Arg467) of α-glucosidase and the hydrophobic effects. These results provide new insight into the inhibitory mechanisms of hesperidin on α-glucosidase, supporting the potential application of a hesperidin-rich orange product as a hypoglycemic functional food.

Hyperspectral dimension reduction and navel orange surface disease defect classification using independent component analysis-genetic algorithm

Canker is a common disease of navel oranges that is visible before harvest, and penicilliosis is a common disease occurring after harvest and storage. In this research, the typical fruit surface, canker spots, penicillium spore, and hypha of navel oranges were, respectively, identified by hyperspectral imaging. First, the light intensity on the edge of samples in hyperspectral images was improved by spherical correction. Then, independent component images and weight coefficients were obtained using independent component analysis. This approach, combined with use of a genetic algorithm, was used to select six characteristic wavelengths. The method achieved dimension reduction of hyperspectral data, and the testing time was reduced from 46.21 to 1.26 s for a self-developed online detection system. Finally, a deep learning neural network model was established, and the four kinds of surface pixels were identified accurately.

Hesperidin: A Review on Extraction Methods, Stability and Biological Activities

Hesperidin is a bioflavonoid occurring in high concentrations in citrus fruits. Its use has been associated with a great number of health benefits, including antioxidant, antibacterial, antimicrobial, anti-inflammatory and anticarcinogenic properties. The food industry uses large quantities of citrus fruit, especially for the production of juice. It results in the accumulation of huge amounts of by-products such as peels, seeds, cell and membrane residues, which are also a good source of hesperidin. Thus, its extraction from these by-products has attracted considerable scientific interest with aim to use as natural antioxidants. In this review, the extraction and determination methods for quantification of hesperidin in fruits and by-products are presented and discussed as well as its stability and biological activities.

High Hydrostatic Pressure vs. Thermal Pasteurization: The Effect on the Bioactive Compound Profile of a Citrus Maqui Beverage

The effects of high hydrostatic pressure (HHP) compared to thermal pasteurization (TP) were studied in healthy citrus-maqui beverages. The impact of the processing technologies on the microbiological and phytochemical profile was assessed by applying two HHP treatments at 450 and 600 MPa for 180 s and TP at 85 °C for 15 s. The shelf life under refrigeration (4 °C) and room temperature (20 °C) was monitored for 90 days. All treatments ensured microbiological stability at both storage temperatures. Aside from that, the physicochemical parameters were not significantly different after processing or throughout the storage period. Regarding color parameters, an increase in the reddish coloration was observed during storage for those beverages treated by HHP. In general, phenolic compounds were little affected by the processing technique, even when treatment under HHP was more stable than by TP during storage. On the other hand, vitamin C showed great degradation after processing under any condition. It can be concluded that HHP is an effective alternative to thermal treatments, achieving effective microbial inactivation and extending the shelf life of the juices by contributing to a better preservation of color and bioactive compounds.

Oxidative Stability, Color, and Physicochemical and Sensorial Properties of Raw Stacked and Ground Meat Treated with Shahpouri Orange Juice

Shahpouri orange juice (SOJ) is a rich source of bioactive compounds including flavonoids and phenolic acids. However, limited studies have been done to determine its effect on stacked and ground meat quality. The study was performed to determine and compare the effects of 0, 200, 400, 600, and 800 ppm SOJ with 200 ppm BHA on stacked and ground beef quality. The flavonoid compounds of SOJ were quantified as well as its antioxidant activity. Surface color, pH, lipid oxidation (peroxide value (PV) and thiobarbituric acid (TBA)), and sensorial properties of stacked and ground beef were determined at a day of SOJ incorporation and then after 6 days of storage at 4°C. The addition of SOJ affected pH compared to the control sample. Incorporating SOJ in stacked and ground meat improved redness and decreased lipid oxidation (PV and TBA) during storage compared with control. SOJ at 800 ppm improved overall sensorial properties after 6 days of storage. These results suggested that SOJ could be used as a natural antioxidant in stacked and ground meat to limit lipid oxidation and discoloration.