Fresh-cut Apples Research Articles

Improved characterization of nanofibers from bacterial cellulose and its potential application in fresh-cut apples

The present research aimed to study the nanofibers from bacterial cellulose (BC) by HCl hydrolysis and explore its new potential application in fresh-cut apples. Bacterial cellulose nanofibers (BCNs) showed low and more homogeneity particle size, as well as higher zeta potential and transparency in comparison with BC, which was confirmed by morphological analysis. Physical properties analysis showed that BCNs was more excellent semi-crystalline polymer with higher thermal stability as compared with BC. Rheological results displayed that BCNs suspensions presented a shear thinning behaviour with higher apparent viscosity, storage (G′) and loss (G′′) moduli at the same concentration in comparison with BC. Furthermore, BCNs suspensions were more stable than BC suspensions under storage condition of 4 °C. Additionally, 2% (wt%) of BCNs suspensions were coated on fresh-cut apples. Results showed that the samples coated with BCNs suspension displayed more excellent properties of keeping fresh-cut apples as compared with that coated with BC suspensions, including delaying weight loss, improving firmness and soluble solids content, reducing browning index and titratable acidity. Therefore, the low cost and high biocompatibility of BCNs can be used as new coatings for fresh-cut apples and have great potential to coat fresh-cut fruits and vegetables in food industry.

Effects of Pre-Processing Hot-Water Treatment on Aroma Relevant VOCs of Fresh-Cut Apple Slices Stored in Sugar Syrup.

In practice, fresh-cut fruit and fruit salads are currently stored submerged in sugar syrup (approx. 20%) to prevent browning, to slow down physiological processes and to extend shelf life. To minimize browning and microbial spoilage, slices may also be dipped in a citric acid/ascorbic acid solution for 5 min before storage in sugar syrup. To prevent the use of chemicals in organic production, short-term (30 s) hot-water treatment (sHWT) may be an alternative for gentle sanitation. Currently, profound knowledge on the impact of both sugar solution and sHWT on aroma and physiological properties of immersed fresh-cuts is lacking. Aroma is a very important aspect of fruit quality and generated by a great variety of volatile organic compounds (VOCs). Thus, potential interactive effects of sHWT and sugar syrup storage on quality of fresh-cut apple slices were evaluated, focusing on processing-induced changes in VOCs profiles. Intact ’Braeburn’ apples were sHW-treated at 55 °C and 65 °C for 30 s, sliced, partially treated with a commercial ascorbic/citric acid solution and slices stored in sugar syrup at 4 °C up to 13 days. Volatile emission, respiration and ethylene release were measured on storage days 5, 10 and 13. The impact of sHWT on VOCs was low while immersion and storage in sugar syrup had a much higher influence on aroma. sHWT did not negatively affect aroma quality of products and may replace acid dipping.

Optimisation of Physical and Chemical Treatments to Control Browning Development and Enzymatic Activity on Fresh-cut Apple Slices.

Optimisation of processing time and pre-treatments are crucial factors prior to apple drying to produce a high-quality product. The purpose of the present study was to test the utility of physical (hot-water, HWB and steam blanching, SB) and chemical (1% ascorbic acid, AA; and 1% citric acid, CA) treatments, alone or in combination in reducing surface discolouration as well as oxidative enzyme activity in apple slices (cv. Golden Delicious and Elstar) exposed to air at room temperature for 0, 30 and 60 min. The total colour change (ΔE) for Golden Delicious was equal to 2.38, 2.68, and 4.05 after 0, 30 and 60 min of air exposure, respectively. Dipping in AA solution (1% w/v) was found to be the best treatment to limit surface discolouration of both apple cultivars. The best heat treatments to inhibit polyphenol oxidase/peroxidase enzymes activity were 70 °C HWB for Golden Delicious and 60 °C HWB for Elstar slices, both in combination with a solution of 1% AA and 1% CA. The tested apple cultivars were found to require different treatments at minimum ambient air exposure to obtain the best surface colour condition.

Effects of Pre-Processing Short-Term Hot-Water Treatments on Quality and Shelf Life of Fresh-Cut Apple Slices.

Processing, especially cutting, reduces the shelf life of fruits. In practice, fresh-cut fruit salads are, therefore, often sold immersed in sugar syrups to increase shelf life. Pre-processing short-term hot-water treatments (sHWT) may further extend the shelf life of fresh-cuts by effectively reducing microbial contaminations before cutting. In this study, fresh-cut ‘Braeburn’ apples, a major component of fruit salads, were short-term (30 s) hot water-treated (55 °C or 65 °C), partially treated with a commercial anti-browning solution (ascorbic/citric acid) after cutting and, thereafter, stored immersed in sugar syrup. To, for the first time, comprehensively and comparatively evaluate the currently unexplored positive or negative effects of these treatments on fruit quality and shelf life, relevant parameters were analyzed at defined intervals during storage at 4 °C for up to 13 days. Compared to acid pre-treated controls, sHWT significantly reduced the microbial loads of apple slices but did not affect their quality during the 5 day-standard shelf life period of fresh-cuts. Yeasts were most critical for shelf life of fresh-cut apples immersed in sugar syrup. The combination of sHWT and post-processing acid treatment did not further improve quality or extend shelf life. Although sHWT could not extend potential maximum shelf life beyond 10 d, results highlighted the potentials of this technique to replace pre-processing chemical treatments and, thus, to save valuable resources.

Carbon Dioxide Injury Prediction Model for Fresh-Cut Apples

Abstract Carbon dioxide (CO2) injury is one of the key cause affecting the sales of fresh-cut apples during the sales period. The method to warn the time till occurring CO2 injury would be convenient for businesses and consumers, but so far, no one has paid attention. This research aimed to study the change rule of the mechanism of carbon dioxide injury of fresh-cut apples treated with high CO2 concentration. The experiment was conducted at 5, 15, 25 and 35°C for 4 days. Every twelve hours, the fresh-cut apple was analyzed by measuring the changes of firmness, soluble solids concentration, browning index and sensory evaluation. The results showed that sensory scores, firmness and soluble solids concentration decreased over time, while the browning index of freshly cut apple increased rapidly with time. Based on the dynamic model of the browning index, with the CO2 Injury warning model of ready-to-eat apples treated with high CO2 concentration was determined.

Effects of plasma-activated water on microbial growth and storage quality of fresh-cut apple

Fresh-cut ‘Fuji’ apples were immersed for 5 min in plasma-activated water (PAW) generated, by plasma generated with sinusoidal voltages at 7.0 kHz with amplitudes of 6 kV, 8 kV, and 10 kV, designated PAW-6, PAW-8, and PAW-10, respectively. The control group was soaked in distilled water for 5 min instead of PAW. The results indicated that the growth of bacteria, molds, and yeasts was inhibited by PAW treatments during storage at 4 ± 1 °C, especially the microbial inactivation with PAW-8, which was the most efficient. PAW-8 reduced the microbial counts by 1.05 log10CFU g−1, 0.64 log10CFU g−1, 1.04 log10CFU g−1 and 0.86 log10CFU g−1 for aerobic bacteria (aerobic plate counts), molds, yeasts and coliforms on day 12, respectively. In addition, the bacterial counts of fresh-cut apples treated with PAW were <5 log10CFU g−1, which did not exceed to the existing China Shanghai local standard (DB 31/2012–2013) during 12 days of storage. PAW treatments reduced superficial browning of fresh-cut apples without affecting their firmness and titratable acidity. In addition, no significant change was observed in antioxidant content and radical scavenging activity between the PAW-treated and control groups. It is suggested that PAW is a promising method for preservation of fresh-cut fruits and vegetables, which is usually beneficial to the quality maintenance of fresh-cut fruits and vegetables during storage.

Cinnamon essential oil Pickering emulsion stabilized by zein-pectin composite nanoparticles: Characterization, antimicrobial effect and advantages in storage application

Recently, the use of emulsion as a delivery system for essential oils has attracted increasing attention. In this research, cinnamon essential oil Pickering emulsion (ZCCPEs) stabilized by zein-pectin composite nanoparticles (ZCPs) was constructed as an effective antimicrobial system. Thereafter, the influence of ZCPs concentration on the stability of ZCCPEs was studied. The results showed that 0.25% ZCPs could reduce the bioorganic matter by four times compared with 1% ZCPs while maintaining good physical stability. The inhibitory effect of ZCCPEs on two food-related microorganisms (i.e. Alternaria alternata and Botrytis cinerea) was evaluated by antimicrobial assay. In addition, two fresh-cut apple slices models were constructed to systematically evaluate the application potential of ZCCPEs in food preservation. Due to the well dispersibility and sustained-release ability, ZCCPEs showed superior antibacterial performance than pure essential oil. The fabricated zein-pectin based Pickering emulsions might provide a promising alternative for the delivery of antimicrobial essential oils in the food industries.

Characterisation of polysaccharide composite incorporated with turmeric oil for application on fresh-cut apples

Composite edible coatings were made up from two types of polysaccharide which are cassava starch and carboxymethyl cellulose (CMC) incorporated with turmeric oil (TO) as an antioxidation agent. Weight loss, firmness loss and moisture content were studied to determine the effect of composite edible coating incorporated with different TO concentration and dipping times towards the quality of fresh-cut Fuji apples. Findings showed that the coating with 17.5 μL/mL concentration of TO and 180 s dipping time had the lowest weight loss and percentage of firmness loss. While for percentage of moisture content, 17.5 μL/mL concentration of TO with 60 s dipping time had the lowest moisture content loss. Surface morphology was analysed to observe the uniformity of coating on fresh-cut Fuji apples surface. The oxidase enzyme activities of fresh-cut Fuji apples reduce when there is TO present in edible coating. It showed that the coating with 180 s dipping time had the best surface coating compared to 60 s and 300 s dipping time. The composite edible coating emulsion can be huge potential as fresh-cut fruits coating to preserve the quality of the fruits.

Synthesis and anti-tyrosinase mechanism of the substituted vanillyl cinnamate analogues

This study aimed to synthesize and screen tyrosinase inhibitors for delay fruit browning. A series of vanillyl cinnamate analogues were designed and synthesized by simple processes, and the inhibitory effects of all the synthesized derivatives on mushroom tyrosinase were evaluated. In the enzymatic activity test, compounds 21, 22, and 26 had significant (P < 0.05) effect on mushroom tyrosinase at a preliminary screening dose (1 mg/mL in vitro). IC50 analysis showed that the IC50 values of compounds 21, 22 and 26 were 268.5 μM, 213.2 μM and 413.5 μM, respectively. In the cytotoxicity evaluation, Cell Counting Kit-8 (CCK-8) assay showed that compounds 21, 22 and 26 had no significant effect on the proliferation of hepatocyte L02 and B16 melanoma cells at the dosage of 25–200 μM. Inhibition of tyrosinase activity and melanin content in B16 melanoma cells investigations indicated that compounds 21, 22 and 26 inhibited both cellular tyrosinase activity and melanin content dose-dependently and more strongly than the reference standard arbutin. The UV–visible spectra showed compound 22 inhibits the formation of dopamine quinone, further the molecular docking analysis of compound 22 with tyrosinase (PDB: 2Y9X) indicated that compound 22 interacted with the amino acid residues of tyrosinase. The results of anti-browning test showed that compounds 21, 22 and 26 had significant tyrosinase inhibition and anti-browning effects on fresh-cut apple slices at 4 °C in 48 h. Compound 22 could be used as novel tyrosinase inhibitor to delay fruit browning.

Effect of pectin-wax coating on the quality of fresh-cut apples

Efficacy of different coating materials including citric acid (CA) as a control, pectin-wax (PW) mixture and pectin-wax mixture containing pistachio hull extract (PWE) were investigated on the quality characteristics of fresh-cut apples during the storage period. The samples were kept under two separate temperatures at 5 °C for 8 days and at 20 °C for 32h. Changes in weight, color, total phenolic content, were examined at different time points along storage time. Results indicated that the apple pieces coated with PWE showed the lowest increase in browning index followed by samples coated with PW. The applications of coatings were effective on delaying the degradation of samples’ colors. The effect of coating fresh-cut apples with PWE was less pronounced on a* values than on L* and b* values. Furthermore coating with PW was affected L* values significantly. The temperature was also a factor affecting the samples color. It was observed that samples kept at lower temperature have maintained the color coordinates. Weight loss was observed significantly in uncoated samples comparing to those prepared with coating, over time of storage at both temperatures. The coatings were effective in maintaining phenolic components where losing in phenolics was higher in non-coated samples.

Effect of Chitosan-Ascorbic Acid Coatings on the Refrigerated Storage Stability of Fresh-Cut Apples

Using natural antimicrobial substances in edible films becomes crucial to extend the shelf-life of fresh-cut fruits due to the consumers’ preferences. In this study chitosan and ascorbic acid based film was used to improve the shelf-life of fresh-cut apples. Fresh-cut apple cubes were dipped in water (control), ascorbic acid (1%) or mixtures of chitosan–ascorbic acid in different ratios (1%:1%, 2%:2% or 1%:5%) for 5 min. After draining, fresh-cut apples were packed in sterile polypropylene jars and stored at 5 °C for 14 days. The treatment with chitosan and ascorbic acid suppressed browning, retained flesh firmness and maintained phenolic compounds throughout the storage period. Moreover, the treatment with chitosan–ascorbic acid significantly retarded the microbial growth during storage. Those findings suggested that the best performance was acquired in 1% chitosan and 5% ascorbic acid coating. That coating could be practical and useful to prolonging the chemical and microbial shelf lives of fresh-cut apples during refrigerated storage.

From pomegranate marcs to a potential bioactive ingredient: a recycling proposal for pomegranate-squeezed marcs

Pomegranate fruit is recognized as an important source of health compounds and its juicy arils represent the most commercially exploitable part of the fruit. Nevertheless, by-products coming from pomegranate juice processing represent both a challenging disposal problem and a promising source of health ingredients. In particular, the marcs obtained after juice squeezing are usually discarded or used for oil production in virtue of their lipophilic fraction, although the residues of pericarp and arils are proven to still be a good source of hydrophilic compounds such as polyphenols. Pulsed ultrasound-assisted extraction, using just water as solvent, and spray-drying microdispersion, using low methoxyl pectin as polymeric matrix, have been employed, respectively, to extract and formulate the water-soluble bioactive molecules from these by-products. From 100 g of pomegranate fresh marcs, almost the same quantity of phenolic compounds found in 100 mL of the corresponding juice can be extracted with similar antioxidant activity, but with higher content in vitamin C and practically without total soluble solids. The extracts have been sprayed obtaining powders with an encapsulation efficiency of about 50%. The extracts, both before and after the microparticles production, have been characterized and their capacity in inhibition of platelets aggregation induced by thrombin has been tested ex vivo on human platelets (% inhibition: about 60% and 30% before and after microencapsulation, respectively). Finally, fresh-cut apple wedges were enriched by vacuum impregnation with the formulated extracts, tentatively used as potential novel ingredients, obtaining “polyphenol-enriched” apples.

Development of Fresh-cut Apple Slices Enriched with Probiotic Strain Bifidobacterium animalis subsp. lactis BB-12

This study was conducted to investigate the suitability of fresh-cut apple slices as carriers of the probiotic strain Bifidobacterium animalis subsp. lactis BB-12 (B. lactis BB-12). Furthermore, the effect of this strain against the colonization of apple by Escherichia coli O157:H7 was also evaluated. Apple wedges were suspended in an edible solution containing B. lactis BB-12 (greater than 8 log10 cfu mL–1) and/or E. coli O157:H7. Microbiological quality and physicochemical properties (pH, moisture content, soluble solids, titratable acidity, color, and texture) of probiotic samples were evaluated on days 1, 5, 9, and 14 of refrigerated storage. Sensory evaluation was performed on days 1 and 7. The probiotic concentration was above the recommended level of 106 cfu/g during the test period. Co-inoculation with probiotic bacteria neither affected E. coli O157:H7 population dynamics, nor influenced the physicochemical and organoleptic properties of fresh-cut apple wedges. Minimally processed apples seem to be suitable vehicles for probiotic bacteria including B. lactis BB-12. Such probiotic products can be a desirable probiotic food choice for consumers, particularly those who are allergic or intolerant to dairy products. However, further studies are required to address the antagonistic effects of probiotic species on food-borne pathogens.

Potato Peels as a Source of Novel Green Extracts Suitable as Antioxidant Additives for Fresh-Cut Fruits

Potato is a source of different bioactive compounds, and the potato transformation industry produces conspicuous quantities of potato peels as waste. In this context, the objective of this research was twofold: (i) the evaluation of the recovery of bioactive compounds from organic potato byproducts through an innovative multistep green extraction process; (ii) to evaluate the preservation during storage of the main quality-physicochemical parameters of minimally processed apples treated with two different natural extracts obtained. The potato extracts were obtained by solid CO2 cryomaceration followed by solid/liquid extraction based on water or 10% ethanol/water solutions. The efficacy of potato extracts, with or without 1% of citric acid, was tested in comparison with traditional preserving compounds in minimally processed apple preparation. All the extracts were characterized by a high antioxidant power and were rich in phenol compounds, showing a good activity in keeping the qualitative parameters of fresh-cut apple. A significant anti-browning effect as well as a slowing down of the softening of fruits during storage were observed. The obtained results suggest the suitability of the potato extracts as antioxidant additives for fresh-cut fruits, thus avoiding the use of unsafe chemicals.

Effect of fresh–cut apples fortification with lycopene microspheres, revalorized from tomato by-products, during shelf life

Fresh–cut apple browning has been conventionally tried to control with the help of ascorbic acid dips, although such antioxidant effect is limited. Lycopene, absent in apple flesh, is the carotenoid in nature with the highest antioxidant capacity, in special for its cis − isomers. Tomato skin is a low cost by-product with very high lycopene content (7.23 g kg−1) and high potential to be incorporated as an antioxidant agent in antibrowning dipping treatments. High lycopene extraction from tomato skin was achieved with a thermal treatment (75 °C, 1 h) favouring trans − to − cis lycopene isomerization with TiO2 nanoparticles. Lycopene extracts were highly encapsulated (encapsulation efficiency: 92.2%) with the complex coacervation method and the obtained microspheres were then incorporated in dipping treatments (0.5 (L0.5), 1 (L1) or 2 g L–1 (L2)) during fresh–cut apples processing, compared with an ascorbic acid dipping (AA; 10 g L–1). Quality changes (colour, microbial, physicochemical and bioactive compounds) were studied up to 9 d at 5 °C. The L2 dipping controlled better the browning during storage, showing the lowest browning index among treatments (BI = 43.8) after 9 d. Furthermore, L2 dipping did not affect the physicochemical quality of samples, while maintaining a good microbial quality. Incorporation of lycopene microspheres also improved the bioactive quality of samples, still showing total cis − lycopene isomer content of ≈ 20 mg kg−1 after 9 d. Furthermore, chlorogenic acid, the predominant phenolic acid, content was enhanced by 56% in L2 samples after 6–9 d. In conclusion, a dipping treatment of fresh–cut apples including 2 g L–1 lycopene microspheres reduced browning, while quality was maintained and some bioactive compounds even enhanced after 9 d at 5 °C.

Quality Control of Fresh-Cut Apples after Coating Application.

The growing demand for ready-to-eat fresh fruits has led to set-up appropriate strategies for preserving fruit quality and freshness of such commodities. To slow down the deterioration events such as respiration, moisture loss and enzymatic activity, ready-to-eat products should be protected with an edible film. A suitable coating should combine hydrophilic and hydrophobic features to ensure good mechanical and gas barrier properties. Alginate/essential oil nanoformulations, one with low and the other with high oil content, here proposed to protect apple pieces during storage, were first characterized through dynamic light scattering and rheology. The effect of the application of the nanoformulations on the quality parameters of apples stored at 4 °C was considered by evaluating weight loss, pH and titratable acidity, total phenols content and the fruit appearance during storage. Mainly on the basis of pH and titratable acididty variation, the nanoformulation with low oil content resulted eligible for preserving the quality of fresh-cut apple pieces during storage.

Evaluation of the Structure and Biological Activities of Condensed Tannins from Acanthus ilicifolius Linn and Their Effect on Fresh-Cut Fuji Apples.

Condensed tannins (CTS) have been isolated and purified from leaves of Acanthus ilicifolius Linn. And their structures were investigated by three methods: 13C nuclear magnetic resonance (13C NMR), reversed-phase high-performance liquid chromatography (RP-HPLC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results showed that the CTS were a mixture of catechin/epicatechin, galatechin/epicatechin, and amphicin/epigalin, and that the polymer chain lengths were 3-mers to 14-mers. Antityrosinase activities and antioxidant activities of the CTS from A. ilicifolius leaves were further studied. The IC50 of the CTS on mushroom tyrosinase activity was determined to be 19.7 ± 0.13μg/mL, and inhibition type analyses indicated that the CTS were mixed type inhibitors and their inhibition CTS was reversible. The CTS from A. ilicifolius leaves also exhibited potential antioxidant activity. The IC50 of DPPH and ABTS scavenging activities were 104 ± 0.894μg/mL and 86 ± 0.616μg/mL, respectively. And the FRAP value was 758.28 ± 2.42mg AAE/g. In addition, we found that the CTS from A. ilicifolius leaves had an excellent effect on preserving the quality of fresh-cut apples by preventing apples from browning through reducing polyphenol oxidase activities in apples.

Effect of Chitosan and Fish Gelatin Coatings on Preventing the Deterioration and Preserving the Quality of Fresh-Cut Apples.

The effect of fish gelatin and chitosan coatings on the physicochemical characteristics of fresh-cut apples (Malus pumila Mill.), stored at 5 °C and 22 °C, was investigated. Chitosan provided an effective control for microbial growth, maintained firmness during 4 days of storage at room temperature (22 °C), and 12 days at refrigerator (5 °C). The results indicated that chitosan coating caused a significant decrease (p < 0.05) in the L* value of cube color of cut apples. Fish gelatin–chitosan coatings mitigated the L* value and decrease in hue angle of the cut apple samples, at cold storage. Experimental results showed that fish gelatin–chitosan and chitosan coatings, can be used to mitigate the formation of vitamin C, due to respiration, microbial growth, and weight loss at cold storage. Fish gelatin–chitosan coating might be a better combination for maintaining appearance and extending shelf-life of cut apples, compared to only chitosan coatings.

An electrical discrimination method for rot in fresh cut apples using Cole–Cole plots

We evaluated the electrical properties of cut apples with and without rot incidence. Cole–Cole plots were prepared from the frequency characteristics of the electrical impedance of sample tissues and used for the analysis of the rotten samples. The coordinates at the top of the circular arc in Cole–Cole plots of all samples showed a linear regression, and it was estimated that the coordinates were influenced by extracellular fluid resistance. The coordinates of the samples were grouped according to the absence or presence of rot. It was deduced that the decrease in the position of the coordinates was caused by metabolites produced by multiplied bacteria in extracellular fluids. We showed that the Cole–Cole plot coordinates have potential as a simple, low-cost, and quantitative marker to aid in the rapid discrimination of rot in cut apples. This approach could be developed for use in the detection of postharvest disease during fruit processing, aiding in the construction of a high-quality supply-chain, and food-safety management.

Effect of chitosan coatings with and without Stevia rebaudiana and modified atmosphere packaging on quality of cold stored fresh-cut apples

In this study, it was aimed to investigate the changes in polyphenoloxidase (PPO) activity, antioxidant properties and microbiological quality of fresh-cut apple slices coated with chitosan and stevia combinations under MAP (polypropylene-PP, 30 μm) storage at +1 °C for 3 days. The apples were cube-shaped and divided into three samples: i-Control (C, without coating), ii-Chitosan (CH, dipped into film mixture consisting of 0.75% chitosan, 1.5% glycerol and 2% ascorbic acid) and iii-Chitosan-Stevia combination (CHS, same CH film contains 2.5% stevia extract). PPO activity and microbiological (total yeast& mold-TYM and total psychrophilic aerobic bacteria-TPAB, total mesophilic aerobic bacteria-TMAB), total phenolic, antioxidant capacity, O2-CO2% and pH analyzes were performed. Results showed that PPO activity, O2-CO2% and pH values were lower, antioxidant substances were higher than C sample. At the end of the storage, CHS samples showed high PPO activity and antioxidant capacity values compared to CH. TMAB was found in C sample but it was under detectable limit (<2) during storage in CH and CHS samples; TPAB was found under detectable limit (<2) in all samples. Additionally, the chitosan and stevia have reduced the TYM counts. As conclusion; CH and CHS edible films are effective applications for reducing PPO activity and microbial load.