Journal of Food Measurement and Characterization

Mulberry leaf polyphenols (MLP) has been proved to have great potential in antioxidant or antimicrobial activity. However, little is known about its anti-adhesion activity and mechanism against foodborne pathogens. This study investigated the efficacy of MLP of subminimal inhibitory concentrations (sub-MIC) in inhibiting adhesion of Escherichia coli O157:H7 and Listeria monocytogenes on fresh-cut lettuce. MLP of 1/16 MIC did not significantly affect growth of the two pathogens (p > 0.05), but it inhibited both pathogens in adhesion ratios, motility, and extracellular polymeric substances (EPS) production when added in the first 1 h (E. coli O157:H7) or 2 h (L. monocytogenes) (p < 0.05). Flagella- (both pathogens) and pili-related (E. coli O157:H7) genes were significantly downregulated when MLP was added in the first 2 h (p < 0.05). Thus, MLP prevented the biosynthesis of EPS, flagella, and pili, which in turn inhibited the initial adhesion of the two pathogens. The application of MLP is of great safety and efficiency. Therefore, MLP of low concentration can promisingly be applied to control the initial adhesion of pathogens, thoroughly eliminating foodborne pathogens in fresh produce processing.

Seaweed as a source of functionally bioactive components has been well recognized due to its beneficial effects for human health. However, beneficial health effects of seaweeds vary with the different aspects especially geographical location of the seaweed. In the present study, two seaweeds (Sargassum coriifolium, Hypnea pannosa) were collected from Bangladesh and crude extracts were prepared using methanol, ethanol and water as extraction solvent. Here, we determined preliminary phytochemical composition, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of crude extracts using different qualitative and quantitative in vitro assays. Overall, screening of phytochemicals revealed that both the seaweeds contain diverse type bioactive compounds including terpenoid, saponin, phlobatannin, cardiac glycosides, phenolic and flavonoid depending on the seaweed species and extraction solvents used. FT-IR spectroscopy also confirmed the presence of phenols, carboxylic acid, ketones, ethers, aromatics, amides and sulfonates at varying degree. Methanol extract of S. coriifolium and H. pannosa showed highest activity followed by ethanol and water extracts. Here, methanolic extract of S. coriifolium showed highest amount of TPC (128.56 mg of GA/g), TFC (58.29 mg of quercetin/g), DPPH (75.01%, IC50 = 1.03 mg/ml), ABTS (72.24%, IC50 = 1.55 mg/ml), hydrogen peroxide (71.64%, IC50 = 1.98 mg/ml), phosphomolybdenum (28.08 mg of ASE/g) and reducing power assays (938.5208 mg of ASE/g). A positive correlation was found among TPC and different antioxidant assays. These results confirmed the presence of diverse type of chemical composition with its antioxidant activity which will be useful for pharmacological as well as in functional food application.

Chemical modification of the native starch of Mexican Oxalis tuberosa was studied by cross-linking it with different concentrations of epichlorohydrin (0.5–2%). The results showed an extraction yield of 65.1 ± 0.20% (dry basis) for native starch, which can be considered as a potential unconventional source for starch extraction. The amylose contents of native and modified starch decreased from 24.66 to 13.57%, respectively. X-ray diffraction analysis showed an increase in the crystalline part in modified starch. The chemical modification changed the functional properties of starch. The clarity of the paste determined by spectrophotometer at 650 nm showed an inversely proportional relationship with the epichlorohydrin concentration. The lipid absorption index showed an increase up to 210% (using 2% epichlorohydrin) compared to that of native starch. The structure was analyzed by SEM and showed granules before and after the modification an ellipsoid morphology while the polarized light microscopy analysis showed birefringence patterns. The average diameter of the granules evaluated using a particle size analyzer (CILAS) ranged between 31.46 μm and 35.32 μm for modified starch and was 30.36 μm for the native starch, both higher than that of the corn-starch granules (16.10 μm). This makes the Mexican O. tuberosa an option for starch extraction and for application in the food industry.

Inocutis tamaricis, a medicinal fungus, is rich in flavonoids, triterpenes, polyphenols, and other active ingredients. In this study, wild basidiomata of I. tamaricis were used for optimized extraction of fungal flavonoids by ultrasound-assisted deep eutectic solvent (DES) extraction method. The efficiency of the extraction method was optimized based on the one-factor analysis and response surface methodology. Also, the activity analysis of I. tamaricis flavonoids was performed, including 1,1-diphenyl-2-pic-rylhydrazyl (DPPH−) and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) clearance ability, reducing ability, and α-glucosidase inhibitory activity. The optimization results indicated that DES with l-proline and 1,2-propanediol produced the best extraction outcome and the conditions were as follows: moisture content, 20%; ultrasonic power, 300 W; extraction time, 40 min; solid–liquid ratio, 60 mg/mL. Under these extraction conditions, the maximum yield of flavonoids was 26.54 mg/g, which was 77% higher than the traditional ethanol extraction method (15.02 mg/g). The in vitro results indicated that flavonoids extracted from I. tamaricis are potent antioxidants and possess hypoglycemic potential; the DPPH and ABTS free radicals clearance rates and the α-glucosidase inhibition rate were more than 80%. Additionally, the flavonoids reducing ability was 1.449, which was not significantly different from that of the standard product (P < 0.05). In conclusion, the DES extraction method is an effective technique for the extraction of flavonoids from I. tamaricis. These flavonoids with significant antioxidant and hypoglycemic potential can be developed into natural antioxidants and hypoglycemic drugs. This study serves as a basis for the future discovery and application of active ingredients from I. tamaricis.

The decoctions of Dictyota dichotoma, Padina gymnospora, Sargassum wightii, Turbinaria conoides, tea leaf (Camellia sinensis), and commercial tea were prepared separately. The antioxidant, anti-hyaluronidase (anti-wrinkling) and cytotoxic activities of decoctions were assessed. The decoctions were added with milk tea and assessed their physio-palatable property. The results showed that among the four seaweed decoctions (BSDs), Dictyota dichotoma exhibits a remarkable antioxidant, anti-hyaluronidase and cytotoxic properties. The decoctions of tea leaf, Dictyota dichotoma, Padina gymnospora, Turbinaria conoides and Sargassum wightii had the cytotoxic property with IC50 of 64.68, 73.24, 161.35, 203.52, 218.73 µg/ml, respectively against HeLa cell lines. The FTIR of the BSD confirmed the presence of fucoxanthin as the principal compound. After adding milk, the mixture of decoctions prepared by tea and brown seaweeds the pH was increased from 4.97 (commercial tea) to 6.93 (Dictyota dichotoma) that would protect teeth from correction caused by acidic tea decoction besides other health benefits. Hence, it can be used as a healthy and nutritious tea drink to protect the skin from solar radiation as values addition to tea.

The present study investigates the effects of guar gum (GGM) based edible coatings containing citric acid (CA) as antibrowning agents and 0, 3, 5, and 10% of mint leaves extract (ME). The fabricated active film was characterized by measuring its physical and mechanical properties, barrier, antioxidant and antimicrobial activities. Storage tests at 23 °C for 15 days were performed for uncoated ber fruit, neat guar gum-citric acid, and guar gum-citric acid with mint leaves extract. Physicochemical and sensory parameters of coated ber fruit were measured. FTIR confirmed physical interactions between GGM and CA. A film with 10% of ME showed 1.81 ± 0.87 antimicrobial activities and 91.22 ± 024% antioxidant capacity. It displayed reduced respiration rate, TSS, weight loss, and was firmer than the non-coated ber at the storage end. The results designated that the film with 10% ME coating indicated a high perspective to prolong the storability of ber, and sensory aspects of 5 and 10% ME containing film increased, respectively.

Accumulated temperature, representing the sum of average daily temperatures, is an objective index for assessment of the maturity of vegetable and fruit crops, including melon. We attempted to manage melon cultivation using time–temperature indicators (TTIs), that reflect temperature history during the cultivation period. The objective of this study was to develop a method for simple prediction and estimation of melon maturity using TTIs based on the Maillard reaction to assist in the decision of when to harvest melons. We examined the performance of TTIs during melon cultivation in greenhouses. Prototype TTIs were prepared using a combination of d-xylose (1.0–2.0 mol/kg) and glycine (2.0–3.5 mol/kg) and the correspondence between changes in color and time–temperature histories of melons during cultivation investigated. The color of TTIs changed from colorless to dark brown, as expected. In some areas of the greenhouse, accumulated temperatures differed by more than 50 °C day, depending on location within the greenhouse, resulting in variation in the color development of TTIs. TTIs could successfully indicate differences in accumulated temperatures, due to temperature irregularities in a greenhouse, as a difference in color. Furthermore, the relationship between accumulated temperature and melon quality at harvest time was investigated. Accumulated temperature was positively correlated with soluble solids content (SSC) and negatively correlated with melon firmness. The prototype TTIs corresponded well with the level of melon maturity, and can indicate SSC and firmness by color development; therefore, they have potential for use in prediction of individual melon maturity during cultivation.

This study was conducted to evaluate the feasibility of using near-infrared spectroscopy (NIRS) for simultaneous determination of total phenolic content (TPC) and antioxidant properties of Siraitia grosvenorii, specifically 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Partial least squares (PLS) coupled with wavelength selection was applied to develop NIRS calibration models based on a set of 80 samples. All models established were cross- and test set validated. The root mean square error of cross validation (RMSECV) and the coefficient of determination for cross validation $$\left( {{\text{R}}_{{{\text{cv}}}}^{2} } \right) $$ were calculated to evaluate the performance of models. The results showed good precision of models for TPC ($${\text{R}}_{{{\text{cv}}}}^{2}$$ = 0.9829, RMSECV = 0.0426), DPPH ($${\text{R}}_{{{\text{cv}}}}^{2}$$ = 0.9477, RMSECV = 0.0279), ABTS ($${\text{R}}_{{{\text{cv}}}}^{2}$$ = 0.8958, RMSECV = 0.0154), and FRAP ($${\text{R}}_{{{\text{cv}}}}^{2}$$ = 0.9137, RMSECV = 0.0176). In addition, 20 unknown samples were used to evaluate the predictive ability of the obtained models, and the ratio performance deviation (RPD) for TPC, ABTS, DPPH, and FRAP ranged from 2.70 to 4.57, which indicate that these models had acceptable predictive ability. These results demonstrated that NIRS has the potential to be a time saving and cost-effective method for the determination of both TPC and antioxidant capacities of Siraitia grosvenorii.