Physiological and quality changes of fresh-cut pineapple treated with antibrowning agents

Effect of Composite Edible Coatings Combined with Modified Atmosphere Packaging on the Storage Quality and Microbiological Properties of Fresh-Cut Pineapple

This study investigated the effect of edible coating (EC), modified atmosphere packaging (MAP), and edible coating + modified atmosphere packaging (EC + MAP) treatments on the quality of fresh-cut pineapples during storage at 4 °C. The quality differences were analyzed by measuring the quality, physiological indicators, and total microbial counts. After 8 d of storage, the brightness (L*) values of the EC + MAP and control samples were 72.76 and 60.83, respectively. The water loss and respiratory rate of the EC + MAP were significantly inhibited from 0% and 29.33 mg CO₂ kg^-1 h^-1 to 4.13% and 43.84 mg CO₂ kg^-1 h^-1, respectively. Furthermore, the fresh-cut pineapples treated with EC + MAP presented a good appearance, with lower total soluble solids (TSS) and relative conductivity and higher titratable acid (TA), ascorbic acid (AA), total phenol content, and firmness compared to the other treatment groups. At the end of storage, the EC + MAP samples exhibited the lowest polyphenol oxidase (PPO) activity, peroxidase (POD) activity, and malondialdehyde (MDA) content at 28.53 U, 60.37 U, and 1.47 nmol·g^-1, respectively. Furthermore, the efficiency of EC + MAP treatment exceeded that of EC or MAP alone, preventing key problems involving the surface browning and microbiological safety of the fresh-cut pineapples. The results showed that EC + MAP treatment was more successful in maintaining the storage quality and extending the shelf life of fresh-cut pineapples.

Influence of Scion/Rootstock reciprocal effects on post-harvest and metabolomics regulation in stored peaches

Peach is an important stone fruit crop cultivated at commercial scale in Pakistan. While, appropriate selection of rootstock has significant impact on the quality of peach fruit. Therefore, in the current study the influence of three rootstocks viz. ‘GF-677′, ‘Peshawar Local’ and ‘Swat Local’ were evaluated on the quality of ‘Flordaking’ peaches following cold storage during two consecutive years. The fruit from these rootstocks were kept at 0 °C for five weeks were studied for various fruit physical (weight loss, colour, firmness) and biochemical (pH, soluble solids content (SSC), titratable acidity (TA), SSC:TA ratio, fruit juice pH, sugars (total, reducing and non-reducing sugars), ascorbic acid (vitamin C) and free radicals scavenging activities) were evaluated. During both years, fruit harvested form trees grafted on ‘GF-677′ exhibited reduced fruit weight loss, changes in Chroma (C*) and highest fruit firmness, Lightness (L*), ascorbic acid contents and radical scavenging activities as compared to fruit harvested from tree grafted on other rootstocks. In conclusion, the post-harvest quality of scion ‘Flordaking’ peach fruit was significantly influenced and best quality can be obtained when it is grafted on ‘GF-677′ rootstock.

Mild Pretreatments to Increase Fructose Consumption in Saccharomyces cerevisiae Wine Yeast Strains

The present research investigates the effect of different pretreatments on glucose and fructose consumption and ethanol production by four Saccharomyces cerevisiae wine strains, three isolated and identified from different wine regions in Turkey and one reference strain. A mild stress temperature (45 °C, 1 h) and the presence of ethanol (14% v/v) were selected as pretreatments applied to cell cultures prior to the fermentation step in synthetic must. The goodness fit of the mathematical models was estimated: linear, exponential decay function and sigmoidal model were evaluated with the model parameters R² (regression coefficient), RMSE (root mean square error), MBE (mean bias error) and χ² (reduced Chi-square). Sigmoidal function was determined as the most suitable model with the highest R² and lower RMSE values. Temperature pretreatment allowed for an increase in fructose consumption rate by two strains, evidenced by a t90 value 10% lower than the control. One of the indigenous strains showed particular promise for mild temperature treatment (45 °C, 1 h) prior to the fermentation step to reduce residual glucose and fructose in wine. The described procedure may be effective for indigenous yeasts in preventing undesirable sweetness in wines.

Mass Transfer Behavior During Osmotic Dehydration and Vacuum Impregnation of “Phulae” Pineapple and the Effects on Dried Fruit Quality

The influence of osmotic dehydration (OD) in combination with vacuum impregnation (VI) technique on the mass transfer behavior of “Phulae” pineapple was investigated. Pineapple slices of 10 mm thick were immersed in sucrose solution at concentrations of 55 and 65oBrix under atmospheric pressure or vacuum pressures at 250 mmHg (VOD-250) and 450 mmHg (VOD-450). The results deduced that 65o Brix of sucrose solution for 300 min and the vacuum pressure of VI at 450 mmHg were necessitated to increase solute uptake to 14.79 g/100 g when compared to other treatments. Surprisingly, the effect of OD and VI on water loss was not much different. Scanning electron microscope (SEM) showed that the pore sizes of pineapple slices were decreased when the impregnation period increased implying the higher adsorption of sucrose into the fruit structure. Subsequently, calcium lactate (Ca-L) at 2, 4 and 6% (w/w) was incorporated in sucrose solution prior to drying at 60oC in a conventional hot air dryer. It was observed that increasing concentration of Ca-L led to a significant decrease in moisture content (17.74 to 15.53%) and water activity (0.58 to 0.56) whereas calcium content was increased (24.472 to 676.317 mg/100g). However, it should be noted that high concentration of Ca-L had adverse effect on sensory property where overall actability decreased from 7.09 to 5.65 as well as total phenolic content (TPC) (17.74 to 15.53 gGAE/100g), DPPH (223.51 to 159.7 µmol Trolox/100g) and FRAP (380.65 to 291.57 µmol ascorbic acid/100g) values.

Evaluation and modeling of changes in color, firmness, and physicochemical shelf life of cut pineapple (Ananas comosus) slices in equilibrium-modified atmosphere packaging

In this study cut, pineapple slices of 1 cm thick were packaged and stored at different temperatures and equilibrium modified atmosphere packages (EMAPs) to determine changes of color and firmness over time to represent physicochemical shelf life. From the experimental data, a variance analysis was performed to determine the effect of temperature and O₂ level on the evolution of color (CIELAB coordinates) and firmness. It was observed that the evolution in L^* , a^* , and b^* coordinates is independent on O₂ concentration in the EMAP system. After that, suitable models were adjusted to represent the change of the quality properties as a function of temperature by using first-order models to represent color and a power model for firmness. Likewise, a modified normal distribution function was adjusted to represent the coefficient of firmness loss depending on the O₂ level besides the temperature effect. The firmness model was used to obtain a suitable equation to predict shelf life of the pineapple slices for different EMAP systems. Finally, a validation experiment was performed at 8 °C obtaining a high capacity of prediction (R² _adj > 0.90) compared with the experimental data. The adjusted model can be used to configure a satisfactory EMAP system for the best preservation of minimally processed pineapple from the predicted evolution of color, firmness, and shelf life depending on temperature and O₂ concentration. PRACTICAL APPLICATION: In this work, we built a mathematical model to simulate the shelf life of pineapple cut into slices based on changes in color and firmness and as a function of temperature and oxygen level. These properties are truly relevant because they are very clear evidence of the fruit deterioration, and for that reason, we chose them for the model. The model we developed can be applied in retail and supermarket systems to determine precisely how long the product on the shelf can last before being disposed of, reducing material losses.

Useful tissues in cabbage head for freshness evaluation with visible and near infrared spectroscopy

To determine which cabbage head tissues are useful for evaluating freshness using spectroscopic technology, we stored wrapped and unwrapped cabbage heads for up to 30 d, and measured visible and near infrared spectra (420-2500 nm) of the 1st-10th leaf layers and cores. We found that spectral changes in leaves were affected both by leaf layer and storage conditions, while continuous spectral changes were observed in the cores regardless of storage condition. These spectral changes in the leaves and cores were consistent with color images and water content. While we developed good models for estimating the storage days from the 1st and 2nd leaf layers and the cores of unwrapped cabbages, only core spectra provided a high correlation with storage days in wrapped cabbages. These data demonstrated that the cabbage core is sensitive to storage duration and its spectra are useful for evaluating freshness decline regardless of storage condition.

Postharvest Application of Aloe vera Gel-Based Edible Coating to Improve the Quality and Storage Stability of Fresh-Cut Papaya

Ready-to-eat products are damaged by various factors, including exposure to O2 and CO2, extreme temperatures, and rapid decay, due to trauma during processing. The use of natural antimicrobial agents and antioxidants might extend the shelf-life of the fruits. The aim of this work is to investigate the effects of four different antibrowning and gelling agents added into the Aloe vera gel-based edible coatings and applied to fresh-cut papaya. EC1 treatment consists of Aloe vera gel (30% v/v), EC2 contains CaCl2 (5% v/v), EC3 contains K carrageenan (0.5% v/v), and EC4 contains sodium alginate (1.5% v/v) and K carrageenan (0.5% v/v). The fruits treated with EC2 showed the best results while maintaining high values in terms of firmness (that differ from the control of 42.5%), soluble solid content (that differ from the control of 14.6%), and titratable acidity (that differ from the control of 49%). Hence, the addition of CaCl2 also reduces the ripening rate and loss of color without altering the product’s sensory qualities. EC3 and EC4 treatments have provided an oxygen barrier and reduced respiratory rate, increasing the firmness retention and keeping a high C∗ value thanks to K carrageenan and sodium alginate.

Changes of Quality of Minimally-Processed Pineapple (Ananas comosus, var. 'Queen Victoria') during Cold Storage: Fungi in the Leading Role

Minimally-processed pineapple stored under refrigerated conditions is highly perishable. We aimed to characterize the evolution of physicochemical, sensory and microbiological quality during cold storage. Pineapple batches were sampled from several locations in Reunion Island and then minimally processed. In the processing step, the variability of firmness and counts of yeasts and molds were observed. Moreover, correlations between the sampling season and pH and b* color component, as well as between fungal population and b* parameter were observed. During storage, the visual aspect of pineapple cuts changed to brown and shiny, whereas olfactive descriptors shifted from fruity descriptors and fresh to fermented, alcoholic and milky. The values for pH, TA and TSS did not significantly vary according to storage time. A decrease in firmness and C* color parameter was observed. Yeast and mold counts were significantly higher after 7 days of storage. The diversity in yeasts and molds was mainly dependent on the considered batches observed from PCR-DGGE profiles. Fungal species were isolated from spoiled pineapple cuts. The implication of Penicilllium citrtrinum, Talaromyces amestolkiae, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, and Meyerozyma caribbica in the spoilage of minimally-processed pineapple cuts was further demonstrated.

Utilization of physicochemical variables developed from changes in sensory attributes and consumer acceptability to predict the shelf life of fresh-cut mango fruit

Sensory evaluation is the ideal tool for shelf-life determination. With the objective to develop an easy shelf-life indicator, color (L*, a*, b*, chroma and hue angle), total soluble solids (TSS), firmness (F), pH, acidity, and the sensory attributes of appearance, brightness, browning, odor, flavor, texture, color, acidity and sweetness were evaluated in fresh cut mangoes (FCM) stored at 5, 10, 15 and 20 °C. Overall acceptability was evaluated by consumers. Correlation analysis between sensory attributes and physicochemical variables was carried out. Physicochemical cut-off points based on sensory attributes and consumer acceptability was obtained by regression analysis and utilized to estimate FCM shelf-life by kinetic models fitted to each variable. The validation of the model was done by comparing the shelf life estimated by kinetic models and consumers. It was recorded large correlations between appearance, brightness, and color with L*; appearance and color with chroma and hue angle; sweetness and flavor with TSS, and between F and texture. The shelf life estimated based on consumer using a 9 point hedonic scale was in the range of 10-12, 2.3-2.6, 1.3-1.5 and 1.0-1.1 days for 5, 10, 15 and 20 °C. It was recorded large correlation coefficients between the shelf life estimated by consumer acceptability scores and physicochemical variables. Kinetic models based on physicochemical variables showed a tendency to overestimate the shelf life as compared with the models bases on the sensory attributes. It was concluded that physicochemical variables can be used as a tool to estimate the FCM shelf life.

Effects of high-pressure argon and nitrogen treatments on respiration, browning and antioxidant potential of minimally processed pineapples during shelf life

BACKGROUND

High-pressure (HP) inert gas processing causes inert gas and water molecules to form clathrate hydrates that restrict intracellular water activity and enzymatic reactions. This technique can be used to preserve fruits and vegetables. In this study, minimally processed (MP) pineapples were treated with HP (∼10 MPa) argon (Ar) and nitrogen (N) for 20 min. The effects of these treatments on respiration, browning and antioxidant potential of MP pineapples were investigated after cutting and during 20 days of storage at 4 °C.

RESULTS

Lower respiration rate and ethylene production were found in HP Ar- and HP N-treated samples compared with control samples. HP Ar and HP N treatments effectively reduced browning and loss of total phenols and ascorbic acid and maintained antioxidant capacity of MP pineapples. They did not cause a significant decline in tissue firmness or increase in juice leakage. HP Ar treatments had greater effects than HP N treatments on reduction of respiration rate and ethylene production and maintenance of phenolic compounds and DPPH(•) and ABTS(•+) radical-scavenging activities.

CONCLUSION

Both HP Ar and HP N processing had beneficial effects on MP pineapples throughout 20 days of storage at 4 °C.