Effect of Nano Silicon Dioxide Coating Films on the Quality Characteristics of Fresh-Cut Cantaloupe

Multiple potential strategies for the application of nisin and derivatives

Nisin is a naturally occurring bioactive small peptide produced by Lactococcus lactis subsp. lactis and belongs to the Type A (I) lantibiotics. Due to its potent antimicrobial activity, it has been broadly employed to preserve various food materials as well as to combat a variety of microbial pathogens. The present review discusses the antimicrobial properties of nisin and different types of their derivatives employed to treat microbial pathogens with a detailed underlying mechanism of action. Several alternative strategies such as combination, conjugation, and nanoformulations have been discussed in order to address several issues such as rapid degradation, instability, and reduced activity due to the various environmental factors that arise in the applications of nisin. Furthermore, the evolutionary relationship of many nisin genes from different nisin-producing bacterial species has been investigated. A detailed description of the natural and bioengineered nisin variants, as well as the underlying action mechanisms, has also been provided. The chemistry used to apply nisin in conjugation with natural or synthetic compounds as a synergetic mode of antimicrobial action has also been thoroughly discussed. The current review will be useful in learning about recent and past research that has been performed on nisin and its derivatives as antimicrobial agents.

Preparation of chitosan/Enoki mushroom foot polysaccharide composite cling film and its application in blueberry preservation

In this study, the composite cling film was prepared by solution casting method using chitosan and golden mushroom foot polysaccharide as substrates, and the structure and physicochemical indexes of the composite cling film were characterized by Fourier infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results showed that compared with single chitosan film, the composite cling film has better mechanical properties and antioxidant properties, and the barrier of UV light and water vapor is also stronger. Due to its high nutritional value, blueberry has a short shelf life due to its thin skin and poor storage resistance. Therefore, in this study, blueberry was used as the object of freshness preservation, and the single chitosan film group and the uncovered group were used as controls, and the weight loss, total bacterial colony, decay rate, respiration intensity, malondialdehyde content, hardness, soluble solids, titratable acid, anthocyanin content, and VC content of blueberry were used as freshness preservation indexes for experiments. The comprehensive results showed that the freshness preservation effect of the composite film group was significantly higher than that of the control group, with better antibacterial properties, antioxidant properties, etc., which could effectively delay fruit decay and deterioration, thus prolonging the shelf life, and thus the chitosan/Enoki mushroom foot polysaccharide composite preservation film has a high potential as a new freshness preservation material for blueberry.

Effects of chitosan and nano-SiO2 concentrations on the quality of postharvest guavas (Psidium guajava L.)

Guava (Psidium guajava L.) is a perishable fruit susceptible to postharvest losses at tropical ambient temperature. Therefore, the development of green storage solution such as biodegradable film could be an alternative to increase guavas’ shelf life. The primary objective of the present work was to explore the effects of combining chitosan and nano-SiO2 coating at different concentrations on the external and internal quality parameters of guavas during 12-d storage at 15°C, and 8-d storage at 30°C. Weight loss, skin colour, firmness, ascorbic acid content, total soluble solids (TSS), decay incidence, and sensory taste score during storage were also analysed. Guavas coated with 2% chitosan and 0.02% nano-SiO2 film were economically optimum to maintain the tested postharvest quality parameters, including better skin colour, higher TSS, fruit firmness, ascorbic acid content, and good taste scores, while keeping lower weight loss and decay incidence when compared with those of other treatments at both tested temperatures. Therefore, chitosan and nano-SiO2 as a coating is a promising strategy for improving the postharvest quality of guavas.

Active Bionanocomposite Coating Quality Assessments of Some Cucumber Properties with Some Diverse Applications during Storage Condition by Chitosan, Nano Titanium Oxide Crystals, and Sodium Tripolyphosphate

Cucumbers have a short shelf-life of about 14 days, they are perishable due to the high moisture content. This study aimed to study the effects of nano-coating material such as titanium nanoparticles and chitosan with the addition of sodium tripolyphosphate as a crosslinker to enhance cucumber quality during storage. Some essential physical, chemical, and biological parameters were determined. CH-Nano-ST (chitosan/nano titanium oxide crystals/sodium tripolyphosphate) retained the maximum greenness, −7.99, compared to CH-Nano samples, which recorded −7.31. CH-Nano (chitosan/nano titanium oxide crystals) remained the lightest, 44.38, and CH-Nano-ST was a little darker (43.73) compared to the others treatments. The discoloration was extra severe with control (22.30), which started to spoil after the end of the first week. After 21 days of the storage period at 10 °C, the reducing sugars content reduced to reach −0.64 g/100 g and −0.21 g/100 g for CH-Nano and CH-Nano-ST treatments, respectively. The CH-Nano-ST treatment presented a lower value of toughness, followed by CH-Nano at the end of the storage period. Moreover, the highest crispness index was detected for CH-Nano (5.12%), while CH-Nano-ST treatment had a slight decline to reach 4.92%. The biological results indicated that CH-Nano-ST treatment can be applied to delay the microbial contamination of Salmonella spp. in cucumbers as it reached 0.94 log CFU/g, while the CH-Nano treatment reached 1.09 log CFU/g, at the end of the storage period. In summary, nano-coating treatments with the addition of sodium tripolyphosphate can be applied to regulator postharvest quality measurements of the biological activities in cucumbers during storage at 10 °C until 21 days.

Evaluating the coating process of titanium dioxide nanoparticles and sodium tripolyphosphate on cucumbers under chilling condition to extend the shelf-life

Cucumber is a highly perishable fruit, that can easily suffer from water loss, condensation, shriveling, yellowing and decay. The present investigation aim was to extending the shelf-life of cucumber using eco-friendly sodium tripolyphosphate and nano-material. Decay; hardness; succinate dehydrogenase activity (SDH); condensation and shriveling rates; and visual quality assessments of cucumbers fruits were evaluated during 21 days of storage period at 10 °C. There was a slight incidence of decay among (Chitosan/Titanium Dioxide Nanoparticles) CS-TiO₂ and (Chitosan/Titanium Dioxide Nanoparticles/Sodium Tripolyphosphate) CS-TiO₂-STP samples, which reported the lowest decay incidence 2.21% in CS-TiO₂, while CS-TiO₂-STP did not show any decay at end of storage period. CS-TiO₂-STP recorded the lowest value in SDH activity 0.08 ∆OD min⁻¹ mg protein⁻¹. Very slight hardness, water condensation, and shriveling were detected in CS-TiO₂ samples, while CS-TiO₂-STP was the lowest compared with other SC samples and control. In general, CS-TiO₂-STP treatment was found most potential to enhance the postharvest shelf life of cucumber throughout the storage period up to 21 day.

Chitosan Edible Films Enhanced with Pomegranate Peel Extract: Study on Physical, Biological, Thermal, and Barrier Properties

In the present study, pomegranate peel extract was used as a reinforcing agent in developing chitosan-based edible film. Different concentrations (0.2 g/mL, 0.4 g/mL, 0.6 g/mL, 0.8 g/mL, and 1.0 g/mL) of pomegranate peel extract were incorporated in chitosan-based edible film. A neat chitosan film was used as a control. This work covers the effect of pomegranate peel extract on the physical, biological, mechanical, thermal, and barrier properties of enriched chitosan-based edible film. The results showed that the thickness (0.142-0.159 mm), tensile strength (32.45-35.23 MPa), moisture (11.23-15.28%), opacity (0.039-0.061%), water (1.32-1.60 g·mm/m2), gas barrier properties (93.81-103.45 meq/kg), phenolic content (5.75-32.41 mg/g), and antioxidant activity (23.13-76.54%) of the films increased with increasing volume fraction of pomegranate peel extract. A higher concentration of incorporated pomegranate peel extracts significantly (p < 0.05) reduced the thermal stability of the film, along with its transparency, solubility, swelling, and color. This work revealed that the incorporation of a higher portion of pomegranate peel extract in chitosan film holds significant (p < 0.05) potential for the increase in biological activities of such films in terms of antioxidant and antimicrobial behavior. The properties of pomegranate peel extract-enriched chitosan films could be an excellent cure for free radicals, whereas they could also inhibit the growth of the foodborne pathogens during the processing and preservation of the food. Further studies are needed for the application of pomegranate peel extract-enriched edible films on food products such as fruits and vegetables in order to extend their storage life and improve the quality and safety of preserved food products.

In-Vitro Evaluation of the Antioxidant and Anti-Inflammatory Activity of Volatile Compounds and Minerals in Five Different Onion Varieties

Onions contain high antioxidants compounds that fight inflammation against many diseases. The purpose was to investigate some selected bioactive activities of onion varieties (Yellow, Red, Green, Leek, and Baby). Antioxidant assays and anti-inflammatory activities such as NO production with the addition of some bioactive components were determined and analyzed by using a spectrophotometer. Gas chromatography and mass spectrometry (GC–MS) was used for the volatile compounds, while an Atomic absorption spectrometer was used for mineral determinations. Red variety achieved the highest antioxidant activities. The total flavonoids were between (12.56 and 353.53 mg Quercetin/gin dry weight) (dw) and the total phenol was (8.75–25.73 mg/g dw). Leek, Yellow and Green extracts achieved highly anti-inflammatory values (3.71–4.01 μg/mL) followed by Red and Baby extracts, respectively. The highest contents of sodium, potassium, zinc, and calcium were established for Red onions. Furfuraldehyde, 5-Methyl-2-furfuraldehyde, 2-Methyl-2-pentenal, and 1-Propanethiol were the most predominant, followed by a minor abundance of the other compounds such as Dimethyl sulfide, Methyl allyl disulfide, Methyl-trans-propenyl-disulfide, and Methyl propyl disulfide. The results recommend that these varieties could act as sources of essential antioxidants and anti-inflammatories to decrease inflammation and oxidative stresses, especially red onions that recorded high activities.

Performance Study of Nano/SiO2 Films and the Antimicrobial Application on Cantaloupe Fruit Shelf-Life

In the current study, novel films with chitosan/nano/SiO2/nisin films and their antimicrobial application on cantaloupe fruit shelf-life have been studied. Novel films were prepared by the addition of 1% chitosan, 1% nano silicon dioxide, and 1% nisin and freeze-dried for the performance study. Physicochemical properties such as tensile strength, optical, and thermal properties with the performance characteristics of the novel films were measured. Coated and uncoated cantaloupes with various coating solutions were stored and chilled at 4 °C in a relative humidity of 70% for up to nine days. The microbial population measurements have been detected every three days. Results show that the fourier transform infrared intensity (FTIR) of nano/SiO2 and with the addition of nisin (nano/SiO2/n) were higher than chitosan (CH) film except in the wavenumber (3150–3750 cm−1) films peaks. Novel nanofilms enhanced tensile strength as well as optical and thermal properties. XRD analysis reported two distinct peak values of 32.08 and 45.99 to correspond to nano/SiO2/n film orientation (7095) and (3316), respectively. Zeta potential values and turbidity were increased, while nano/SiO2 films decreased the hydrophobicity of the film surface by 80.07°. The coating treatments with nano/SiO2 and nano/SiO2/n both reduced the yeast and mold counts 2.49 and 1.92 log CFU/g, respectively, on day nine. In summary, chitosan/nano/SiO2/n novel film improved the functional properties of coating films, and those bio-nanocomposites are effective in food packaging.

The combined effect of coating treatments to nisin, nano-silica, and chitosan on oxidation processes of stored button mushrooms at 4 °C

Agaricus bisporus is an edible fungus with a limited shelf life due to high moisture loss, browning, respiration, self-dissolve, lack of physical protection, rotting, and microbial attack. Mushrooms have been coated with nisin, nano-silica, and chitosan films in order to extend the shelf life, preserve quality and oxidation activities. The results showed that treating the mushrooms with chitosan and nano-silica (CH-AN-SILICA) increased superoxide dismutase activity (SOD—6.53 U kg⁻¹), total phenolic content (TPC—0.39 g kg⁻¹), and malondialdehyde content (MDA—1.63 µmol kg⁻¹). CH-AN-SILICA treatment exhibited the highest scavenging against 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. While, CH-AN-SILICA with the addition of nisin as an antimicrobial agent preserved almost the reactive oxygen species such as hydroxyl radicals (OH—0.33 µmol g⁻¹), superoxide anion (O₂^•−—0.271 mmol s⁻¹ kg⁻¹), and hydrogen peroxide (H₂O₂—21.54 µmol g⁻¹). Besides, both CH-AN-SILICA and CH-AN-SILICA/N enhanced the catalase (CAT) activity and reduced the respiration rate. The results indicated that the combination of nisin, nano-silica, and chitosan coating films was effective in providing a longer storage life with acceptable quality in mushrooms.