Quality Of Fresh-cut Apple Slices Research Articles

UV‐C irradiation delays browning of fresh‐cut “Fuji” apples

In order to explore the effect and the corresponding physiological mechanisms of UV-C irradiation on browning of fresh-cut apples, both whole and sliced apple were irradiated with UV-C (254 nm) for 5 min before or after processing. The browning index (BI) of slices was immediately measured, while other relevant physiological parameters were evaluated on quick-frozen samples during refrigerated storage. Results indicated that both pre- and post-processing UV-C treatments effectively delayed browning of apple slices; nevertheless, post-processing UV-C treatment was more efficient. BI significantly negatively correlated with non-enzymatic capacities, and activities of catalase, ascorbate peroxidase, and glutathione reductase (GR). BI was positively correlated with the contents of H2O2 and malondialdehyde (MDA). These findings suggested that UV-C treatment delayed browning of apple slices during cold storage by improving the antioxidant system. Post-processing UV-C treatment was more efficient than pre-processing. Practical applications UV-C treatment is a technique of preservation for fresh-cut fruits. It is widely applied in food processing and many other fields due to its convenience, safety, low cost, etc. In the present study, both pre- and post-processing UV-C (254 nm) irradiation for 5 min could (1) delay the browning of fresh-cut apple, (2) improve the polyphenol oxidase activity and reduce the phenylalanine ammonia-lyase (PAL) activity and total phenolic content (TPC), and (3) reduce the accumulation of H2O2 and malondialdehyde, and increase the antioxidant activities of fresh-cut apples. Thus, UV-C treatments maintain the fresh-cut quality of fresh-cut apple slices and extend their shelf life.

Bilayer edible coating with stabilized Lactobacillus plantarum 299v improved the shelf life and safety quality of fresh-cut apple slices

In this study, a bilayer probiotic edible coating was developed for fresh-cut apple slices. Lactobacillus plantarum 299v-containing carboxymethyl cellulose solution was applied to the apple slices as the primary coating, followed by a secondary coating with zein. As a result, the probiotic bacteria L. plantarum 299v remained stable on the coated apple slices during 7 days storage at 4 °C (>6 log CFU/g) and only manifested a drop of 2.24 ± 0.08 log CFU/g during simulated digestion. The bilayer probiotic edible coating was able to induce significantly less weight loss of the apple slices, suppress yeasts and moulds, and inhibit the proliferation of spiked Listeria monocytogenes during the chilled storage (P < 0.05). Taken together, our results demonstrated that the bilayer probiotic edible coating with stabilized L. plantarum 299v as developed in this study was able to improve the shelf life and safety quality of fresh-cut apple slices.

Effects of pre-treatment with S-nitrosoglutathione-chitosan nanoparticles on quality and antioxidant systems of fresh-cut apple slices

In order to develop a new and effective fruit treatment technology, fresh-cut apple slices were treated with water, S-nitrosoglutathione (GSNO), chitosan, and S-nitrosoglutathione-chitosan nanoparticles (GSNO-CS) and then stored at 4 °C for 4 days to investigate the changes in the quality characteristics and the antioxidant biochemical system. The results indicated that GSNO-CS preserved the quality of fresh-cut apple slices more effectively compared to other treatments. Specifically, fresh-cut apple slices treated with GSNO-CS was detected the higher antioxidant enzymes activities, which was 1–7.2 times that of control samples, and the lowest reactive oxygen species content, which was 8.97%–58.97% of the control. In addition, GSNO-CS kept the surface color and weight of the apple slices in an effective way, and reduced the respiration rate of the apple slices to 21%–47% that of the control during storage. All the results of this study suggested that GSNO-CS treatment effectively preserved the quality and enhanced the antioxidant capacity of fresh-cut apple slices.

Comparison between Hyperspectral Imaging and Chemical Analysis of Polyphenol Oxidase Activity on Fresh-Cut Apple Slices

The assessment of the quality of fresh-cut apple slices is important for processing, storage, market value, and consumption. Determination of polyphenol oxidase activity (PPO) in apples is critical for controlling the quality of the final product (i.e., dried apples and juices). Hyperspectral imaging (HSI) is a nondestructive, noncontact, and rapid food quality assessment technique. It has the potential to detect physical and chemical quality attributes of foods such as PPO of apple. The aim of this study was to investigate the suitability of HSI in the visible and near-infrared (VIS-NIR) range for indirect assessment of PPO activity of fresh-cut apple slices. Apple slices of two cultivars (cv. Golden Delicious and Elstar) were used to build a robust detection algorithm, which is independent of cultivars and applied treatments. Partial least squares (PLS) regression using the 7-fold cross-validation method and method comparison analysis (Bland–Altman plot, Passing–Bablok regression, and Deming regression) were performed. The 95% confidence interval (CI) bands for the Bland–Altman analysis between the methods were −4.19 and 13.11, and the mean difference was 3.7e−12. The Passing–Bablok regression had a slope of 0.8 and an intercept of 7.6. The slope of the Deming regression was 0.8 within the CI bands of 0.56 and 1.10. These results show acceptable performance and no significant deviation from linearity. Hence, the results demonstrated the feasibility of HSI as an indirect alternative to the standard chemical analysis of PPO enzyme activity.

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.

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.

Influence of soluble soybean polysaccharide and tragacanth gum based edible coating to improve the quality of fresh-cut apple slices

Influence of soluble soybean polysaccharide and tragacanth gum based edible coating to improve the quality of fresh-cut apple slices

Respiration and Storage Quality of Fresh-Cut Apple Slices Immersed in Sugar Syrup and Orange Juice

Storing fresh-cut apple slices in suitable fruit juice or sugar syrup is a general practice. However, application of this approach is mainly based on empirical knowledge, while systematic and comprehensive analyses of the relevant effects of this storage technique on keeping quality-related physiological properties of fresh-cut products is still missing. Hence, the aim of this study was to evaluate the impacts of complete immersion of fresh-cut apples in sugar syrup and fruit juice solution on respiratory behaviour and other relevant quality attributes (colour, tissue strength, and soluble solid and acidity). Sugar syrup and pure orange juice showed a high potential to store and protect fresh-cut apples. Results showed that only pure orange juice positively affected the produce quality by preventing browning effects. In addition, sugar syrup of 13.4–20% most effectively prevented browning of apple slices and guaranteed high product quality retention during storage. The application of different liquid media provides a practical means to prevent browning and maintain product quality.

Maintaining quality of fresh-cut apple slices using calcium ascorbate and stored under modified atmosphere

Tissue browning and softening are the main concerns associated with fresh-cut apples. In this study, effects of calcium ascorbate and NatureSeal® on quality parameters of apple slices were investigated. Changes in browning, colour, firmness, and enzymatic activity were measured. Results showed that NatureSeal® had significant effect on controlling browning of cut apples because of the maintained higher Lightness values compared to calcium ascorbate samples. NatureSeal® also inhibited surface browning and reduced firmness loss. The application of NatureSeal® could be used to reduce deteriorative processes, maintain quality, and increase the shelf-life of fresh-cut apple stored at 4 °C.

Effects of 1‐methylcyclopropene and post‐controlled atmosphere air storage treatments on fresh‐cut Ambrosia apple slices

The effect of 1-methylcyclopropene (1-MCP) treatment and two different post-controlled atmosphere air storage (PCAAS) durations on the quality and chemistry of fresh-cut Ambrosia apple slices was studied. PCAAS for 1 or 2 weeks prior to slicing had an overall positive effect on the resultant quality of fresh-cut apple slices. The most significant responses to PCAAS were the suppression of both phenolic and o-quinone accumulation in slices, and this was related to the significantly lower browning potential values obtained for slices from PCAAS-treated apples. Polyphenol oxidase (PPO), peroxidase (POX) and ascorbate peroxidase (APOX) activities were not affected by 1-MCP or PCAAS treatments. PPO and POX activities were almost completely inhibited by a 50 g L⁻¹ calcium ascorbate anti-browning dip of apple slices from all treatments. The most dramatic effect of the PCAAS treatments was to reduce the accumulation of soluble phenolics, which is likely the reason that o-quinone accumulation was also inhibited in treated fruits. The consequent reduction in browning potential may be the explanation as to why PCAAS treatment has been shown to reduce fresh apple slice browning in previous work.

Quality of fresh-cut apple slices stored in solid and micro-perforated film packages having contrasting O 2 headspace atmospheres

This research explored the quality differences for fresh-cut apple slices packaged in two packaging systems having contrasting steady-state headspace O 2 atmospheres. The first film was a solid multi-layered polyolefin film (SF) which established a steady-state headspace atmosphere of high CO 2 and low O 2. The second was an ultra micro-perforated (MP) film which produces a headspace atmosphere consisting of high CO 2 and high O 2. The resultant fruit quality was assessed in fresh-cut ‘Gala’ apple slices for fruit sourced from the northern hemisphere (NH) (British Columbia, Canada) and southern hemisphere (SH) (Chile). Fruit were washed, sliced and dipped in an anti-browning solution, prior to packaging and storing at 5 °C, for up to 21 d. Package headspace compositions were determined using ethylene, CO 2, and O 2 concentration. Volatile analyses (straight chain esters, branched esters, terpenes, alcohols, estragole, other-volatiles, total-volatiles) were conducted on the headspace for the SH slices by gas chromatography. Quality attributes (soluble solids concentration, titratable acidity, color, and relative juice loss) were assessed at 0, 4, 7, 14, and 21 d. Sensory analysis was conducted on day 14. Ten experienced judges evaluated 5 sensory attributes (fruit aroma, fruitiness-by-mouth, sweetness sourness, hardness) and 1 visual attribute (degree-of-browning); whereas, 20 judges assessed overall preference. Apple slices in the MP packages had less juice loss and higher concentrations of estragole, straight chain esters, total and other-volatiles. MP apple slices had significantly ( p ≤ 0.05) higher fruity aroma, fruitiness-buy-mouth, perceived sweetness and better textural characteristics, as perceived by the sensory panel. These superior fruit quality characteristics were attributed to lower ethylene concentrations and high CO 2 and high O 2 levels generated from the MP film.

Effects of calcium ascorbate treatments and storage atmosphere on antioxidant activity and quality of fresh-cut apple slices

Fresh-cut ‘Braeburn’ apple slices were dipped in calcium ascorbate (CaAsc; 0, 2, 6, 12 and 20%, w/w) and stored in air or under modified atmosphere (MA) conditions for up to 28 d at 4 °C. Changes in antioxidant levels were measured using free radical scavenging activity (DPPH), reducing activity (FRAP), ascorbic acid content (AA) and polyphenolic content (by HPLC). Changes in browning, sensory quality and microbial counts were measured to indicate eating quality. CaAsc dips increased the initial levels of AA from 0.19 g kg −1 in the untreated control to 3.8 g kg −1 for the 20% CaAsc treatment. Ascorbic acid content of treated slices during storage decreased by more than 50% in CaAsc concentrations of 6, 12 and 20%. Similar patterns were observed for FRAP and DPPH activities. Untreated or 2% CaAsc treated slices stored in air or MA showed browning, microbial deterioration and poor sensory quality, thus resulting in a short shelf life (<7 d). However, apples dipped in 6 or 12% CaAsc and stored in MA packaging, or dipped in 20% CaAsc and packaged in air or MA had a shelf life of 21–28 d. Total antioxidant activity in these treatments was provided by both exogenous ascorbic acid and endogenous phenolic compounds; the latter varied in composition, but were relatively stable during storage compared with ascorbate in higher CaAsc concentration treatments. Thus, the antioxidant levels (as measured by FRAP and DPPH) were related to shelf life and it appears that an antioxidant activity remaining above 2 g kg −1 (DPPH or FRAP) may be a minimum level to achieve long shelf life in ‘Braeburn’ apple slices.

(34) Maintaining the Analytical and Microbial Quality of Fresh-cut Apple Slices using Hot Water Pretreatment and a Low pH Dip Treatment

A calcium ascorbate processing formulation is commercially used to prevent browning on fresh-cut apple slices but has little to no antimicrobial activity. Intact apples were surface-sanitized with chlorine water at 20 °C or water at 60 °C, processed into fresh-cut slices, and the slices dipped in a calcium ascorbate formulation or a solution of isoascorbic acid, calcium, and N-acetylcysteine at pH 2.0. The commercial and experimental dip treatments similarly maintained cut surface color, Kramer firmness, and aromatic volatile concentrations during 3 weeks of storage at 5 °C in air. Freshly prepared experimental dip treatment reduced the native bacterial population of the apple slices prepared from sanitized apples better than the calcium ascorbate treatment. With repeated use, the experimental dip solution became adulterated with apple tissue and juice and rapidly lost its antibacterial activity. Concomitantly the pH of the dip solution increased to 2.6 or higher. The lost antibacterial activity could be restored in highly contaminated experimental dip solutions by back titrating to pH 2.0. The experimental dip treatment also reduced the overall yeast and mold population, but specifically enhanced growth of Penicilliumexpansum on slices prepared from chlorine-sanitized apples. A hot water pretreatment of intact apples at 60 °C for 3 min prior to fresh-cut processing essentially eliminated P. expansum contamination on the slices. The results indicate that the experimental dip treatment is a promising alternative to calcium ascorbate treatment for analytical and microbial quality retention of fresh-cut apple slices during storage, especially when the apple slices are processed from hot water-treated apples.

Quality of Fresh-cut Apple Slices as Affected by Low-dose Ionizing Radiation and Calcium Ascorbate Treatment

ABSTRACT: Although ionizing radiation effectively inactivates food-borne bacterial pathogens in fresh-cut fruits and vegetables, it may adversely affect product quality. In this study, the effects of calcium ascorbate (CaA) and ionizing radiation on quality of ‘Gala’ apple slices under modified atmosphere packaging were investigated. ‘Gala’ apple slices, treated with water or 7% CaA followed by either nonirradiation (0 kGy) or irradiation at 0.5 and 1.0 kGy, were stored at 10°C for up to 3 wk. The titratable acidity, pH, firmness, ascorbic acid content, color, and microflora population were measured weekly throughout storage. Irradiation did not affect titratable acidity and pH of sliced apples. Fruit slices softened during irradiation and storage, but this decrease in firmness during storage was reduced by the CaA treatment. Although the ascorbic acid content of apple slices treated with CaA decreased rapidly during storage, the ascorbic acid content was always higher in those treated samples than in the apple slices treated with water. Irradiation decreased both L* and hue values of apple slices. Hue values decreased during the entire storage period while L* increased during the 1st wk of storage, then decreased between 1 to 3 wk of storage. CaA increased L* and hue values of apple slices, suggesting CaA reduced browning, even in irradiated samples. The microflora population of apples slices was not affected by CaA, and CaA treatment did not alter the reduction in microflora by irradiation. The combination of CaA and irradiation enhanced microbial food safety while maintaining quality of fresh-cut apple slices.

Effect of 1‐Methylcyclopropene on the Quality of Fresh‐cut Apple Slices

ABSTRACT: The objective of this project was to treat fresh‐cut apple slices with the ethylene inhibitor 1‐methylcyclopropene (1‐MCP) to retard ethylene‐induced deterioration and senescence and to prolong the shelf life of such products. Intact Braeburn and Pacific Rose apples were treated at different times with 1‐MCP, cut, and stored at 0 °C. Samples were analyzed initially and then weekly for ethylene, respiration, flesh firmness, tissue color, titratable acidity, and soluble solids content during 5 wk of storage. 1‐MCP treatment was effective in reducing ethylene production, respiration, and loss of firmness and color of slices when applied to whole apples directly after harvest. Total sugar and acidity levels were not affected significantly.