Fresh-cut Pineapple Research Articles

Investigation of the Effect of Oscillating Magnetic Field on Fresh-Cut Pineapple and Agar Gel as a Model Food During Supercooling Preservation

Abstract. In this study, the effect of an oscillating magnetic field (OMF) on the supercooling of fresh-cut pineapple and agar gel was investigated. The pineapple was preserved in a supercooled state at -7°C, and its supercooled state was maintained for 14 days with the presence of the OMF, whereas the untreated sample was spontaneously nucleated within 24 h. Agar gel was prepared as equivalent to the soluble solids content of pineapple and showed a comparable supercooling behavior when exposed to a similar OMF treatment. Examination of the microstructures showed that cellular damage due to ice crystal formation did not occur in the supercooled pineapple and agar gel, implying that the OMF successfully inhibited ice nucleation during supercooling. The weight losses of pineapple samples preserved with refrigeration, freezing, and supercooling for 14 days were determined to be 7.3%, 23.8%, and 0.8%, respectively. Furthermore, the visual appearance showed that supercooling effectively prolonged the shelf-life of pineapple without freezing damage. The results suggest that the developed OMF technology can inhibit ice nucleation during supercooling and can be used to preserve fresh-cut fruits at subzero temperature while ensuring the food quality. In addition, a solid model food could be used as a substitute for predicting the supercooling behavior of food products. Keywords: Food preservation, Fresh-cut fruit, Oscillating magnetic field, Pineapple, Supercooling.

Growth of Salmonella spp. and Escherichia coli O157:H7 on Fresh-Cut Fruits Stored at Different Temperatures.

The objective of this work was to determine the growth potential of Salmonella spp. and Escherichia coli O157:H7 on fresh-cut honeydew melon, cantaloupe, watermelon, pitaya, mango, papaya, and pineapple stored at 5°C, 13°C, and 25°C. The results showed that both pathogens were able to grow on fresh-cut fruits except fresh-cut pineapple at 13°C and 25°C. Salmonella spp. grew more rapidly on fresh-cut honeydew melon, cantaloupe, watermelon, and mango than did E. coli O157:H7 at 13°C. The growth of both species was inhibited on fresh-cut pineapple, with that of Salmonella spp. being particularly pronounced. Naturally occurring microbiota populations on fresh-cut fruits increased significantly at 13°C and 25°C, but no significant changes in growth were observed for Salmonella spp., E. coli O157:H7, or natural microbiota species at 5°C. The study therefore emphasizes the importance of strict temperature control from processing to consumption, including transportation, distribution, storage, and handling in supermarkets and by consumers.

Layer-by-layer edible coatings based on mucilages, pullulan and chitosan and its effect on quality and preservation of fresh-cut pineapple (Ananas comosus)

Edible coatings (ECs) based on chitosan (CH), pullulan (PU), linseed (LM), nopal cactus (NM) and aloe mucilage (AM) were applied by layer-by-layer technique to preserve the quality and prolong the shelf-life of fresh-cut pineapple. Pineapples were washed, disinfected, dried and cut into 2cm side cubes. Fresh-cut fruit was coated by dipping using four treatments (CH+PU, CH+LM, CH+NM and CH+AM), packed into polyethylene terephthalate containers and stored for 18 d at 4°C. Uncoated fruit was used as control. Application of layer-by-layer ECs decreased (P<0.05) the weight loss, pineapple softening, and, retarded the fall on total soluble solids content and color (L* and a*). CH+AM EC was effective in delaying (P<0.05) ascorbic acid degradation. In contrast, ECs did not affect titratable acidity (P>0.05). Microbiological analyses demonstrated the effectiveness (P<0.05) of the layer-by-layer ECs against spoilage microorganisms, L. monocytogenes and S. typhi. CH+PU EC was the most effective in controlling microbial levels. Sensory analysis demonstrated that layer-by-layer ECs helped to preserve (P<0.05) the quality properties (color, odor, flavor, texture and overall acceptance). In conclusion, layer-by-layer ECs based on CH+PU, CH+LM, CH+NM and CH+AM improved the quality and prolonged the shelf-life of fresh-cut pineapple by six days compared with control.

Effect of 460 nm light emitting diode illumination on survival of Salmonella spp. on fresh-cut pineapples at different irradiances and temperatures

Blue light emitting diodes (LEDs) have emerged as an intervention against Salmonella, which colonizes and grows on fresh-cut fruits. This study evaluated their efficacy on fresh-cut pineapples. Pineapple slices were surface-inoculated with a Salmonella cocktail and illuminated with 460 nm LEDs at different irradiances (92, 147.7 and 254.7 mW/cm2) and temperatures (7, 16 and 25 °C). The resulting differences in the populations of control and illuminated samples were modeled to determine the antibacterial effect. The color of the slices was also measured. Bactericidal action was observed at 7 and 16 °C and growth inhibition at 25 °C. An adapted Weibull model best described the inactivation, with the D values ranging from 15 to 27 kJ/cm2. Temperature influenced the antibacterial effect but the irradiance had no significant effect (P ≥ 0.05). Though the illuminated pineapple slices tended to be bleached, this study demonstrated the potential of 460 nm LEDs against Salmonella on fresh-cut pineapple slices.

Ultrasound treatment on phenolic metabolism and antioxidant capacity of fresh-cut pineapple during cold storage

Ultrasound treatment at different power output (0, 25 and 29W) and exposure time (10 and 15min) was used to investigate its effect on the phenolic metabolism enzymes, total phenolic content and antioxidant capacity of fresh-cut pineapple. Following ultrasound treatment at 25 and 29W, the activity of phenylalanine ammonia lyase (PAL) was increased significantly (P<0.05) by 2.0 and 1.9-fold, when compared to control. Meanwhile, both the activity of polyphenol oxidase (PPO) and polyphenol peroxidase (POD) in fresh-cut pineapple was significantly (P<0.05) lower than control upon subjected to ultrasound treatment. In the present study, induction of PAL was found to significantly (P<0.001) correlate with higher total phenolic content and thus higher antioxidant capacity in fresh-cut pineapple. Results suggest that hormetic dosage of ultrasound treatment can enhance the activity of PAL and total phenolic content and hence the total antioxidant capacity to encounter with oxidative stress.

Physicochemical and microbiological changes in fresh-cut pineapple coated with wheat gluten and alginate

Physicochemical and microbiological changes in fresh-cut pineapple coated with wheat gluten and alginate

Effect of wheat gluten-based edible coating and irradiation on quality of fresh-cut pineapple

Effect of wheat gluten-based edible coating and irradiation on quality of fresh-cut pineapple

Prediction of relationship between surface area, temperature, storage time and ascorbic acid retention of fresh-cut pineapple using adaptive neuro-fuzzy inference system (ANFIS)

Adaptive neuro-fuzzy inference system (ANFIS) was developed for the prediction of ascorbic acid (AA) retention during storage of fresh-cut pineapple as a function of surface area, storage temperature and time. Our results demonstrate that surface area and temperature are the two most important factors influencing the degradation of AA in fresh-cut pineapple during storage. The AA in fresh-cut pineapple with a high surface area is more easily destroyed than that with a low surface area at the same storage temperature. In addition, the ANFIS model with triangular-shaped membership function (trimf) (RMSE=7.88%; R2=0.95) provides the best prediction accuracy than models with other membership functions (RMSE=8.97–10.19%; R2=0.91–0.93). Therefore, the high-surface-area fresh-cut fruit should be stored at a relatively low temperature as compared with the low-surface-area produce. The ANFIS model with trimf is an adequate model for the prediction of AA retention during storage of fresh-cut pineapple.

Impact of UV-C light on storage quality of fresh-cut pineapple in two different packages

The effectiveness of UV-C light treatments on microbial load and quality of fresh-cut pineapple sticks was studied. At all tested fluencies (200–4800 J/m2), UV-C light did not decrease the initial microbial load of pineapple sticks. Nevertheless, pineapple sticks submitted to 200 J/m2 UV-C light, packaged in conventional PET/EVOH/PE trays and stored at 6 °C up to 15 days showed slower yeast and lactic acid bacteria growth. In these samples, microbial counts were generally 2 log cycles lower that those observed in the untreated sticks. UV-C light did not promote changes in colour and increased consumer preference. Similar results were also obtained when UV-C light treatment was applied on pineapple sticks previously packaged in highly UV-C light transparent PA/PE pouches to avoid post treatment contamination.

Growth Potential of Listeria Monocytogenes and Staphylococcus Aureus on Fresh-Cut Tropical Fruits.

The objective of this study was to evaluate the fate of Staphylococcus aureus, Listeria monocytogenes, and natural microbiota on fresh-cut tropical fruits (pitaya, mango, papaya and pineapple) with commercial PVC film at different storage temperature (5, 13, and 25 °C). The results showed that S. aureus, L. monocytogenes, and natural microbiota increased significantly on fresh-cut tropical fruits at 25 °C. Both pathogen and natural microbiota were able to grow on fresh-cut tropical fruits at 13 °C. The maximum population of L. monocytogenes was higher than that of S. aureus on fresh-cut tropical fruits. L. monocytogenes and S. aureus could survive without growth on fresh-cut pitaya, mango, and papaya at 5 °C. The population of L. monocytogenes declined significantly on fresh-cut pineapple at all temperature, indicating composition of fresh-cut pineapple could inhibit growth of L. monocytogenes. However, S. aureus was still able to grow on fresh-cut pineapple at storage temperature. Thus, this study suggests that 4 kinds of fresh-cut tropical fruits (pitaya, mango, papaya, and pineapple) should be stored at low temperature to extend shelf life as well as to ensure the safety of fresh-cut fruits. The data collected in this study demonstrated that L. monocytogenes and S. aureus were able to grow on fresh-cut tropical fruits at different temperatures. These results could be of interest in knowing the capacity of tropical fruits to support the growth of L. monocytogenes and S. aureus. This information may also be useful to local and state regulatory officials responsible for food safety.

EFFECTS OF ASCORBIC AND LACTIC ACIDS ON QUALITY OF FRESHCUT PINEAPPLE (ANANAS COMOSUS)

This study determined the antimicrobial efficacy of ascorbic and lactic acids on freshcut pineapple and evaluated the physicochemical and sensory qualities of the produce. Freshly harvested ripening ‘Queen’ pineapple fruits (about 25% shell yellowing) were obtained from a local plantation, peeled, and sliced as commercially practiced. Ascorbic and lactic acids were applied at 1.5-2.5% as 2 min dip, with 150 ppm chlorine and distilled water as 2 min dip as control. Product samples were packed in sterile resealable 50 I¼m-thick polyethylene bag and stored at 7-10°C for five days. Lactic acid was more effective than ascorbic acid in reducing aerobic and coliform bacteria as well as yeast and mold population. The antimicrobial activities of organic acids were comparable to chlorine after 3 h from treatment but were much better than chlorine after five days of storage. The physicochemical and sensory qualities of freshcut pineapple were not adversely affected by the treatments.

ANTIMICROBIAL POTENTIAL OF LACTIC ACID BACTERIA ON FRESHCUT PINEAPPLE (ANANAS COMOSUS)

Natural preservation using biological agents such as probiotic lactic acid bacteria (LAB) has been singled out as among the emerging technologies where research should focus in order to develop safer and sustainable antimicrobial system. This study was conducted to determine the antimicrobial efficacy of probiotic LAB and the physicochemical and sensory qualities of freshcut pineapple. Freshly harvested ripening ‘Queen’ pineapple fruits (about 25% shell yellowing) were obtained from a local plantation, peeled, and sliced as commercially practiced. Pure culture of Lb. plantarum at 10(9) CFU/ml was applied at 1-3% (v/w) as protective culture. Control treatments included 150 ppm chlorine and distilled water as 2-min dip. The product samples were packed in sterile resealable 50 I¼m-thick polyethylene bag and stored at 7-10°C for five days. Lb. plantarum at 2-3% inhibited aerobic bacteria, coliform and yeast and mold proliferation on pineapple. At 3%, Lb. plantarum reduced the microbial load by about 99% relative to water control after five days of cold storage. Probiotic LAB with 3% concentration had no significant effect on the physicochemical and sensory quality of freshcut pineapple.

Effects of pure oxygen and reduced oxygen modified atmosphere packaging on the quality and microbial characteristics of fresh-cut pineapple

Introduction. Modified atmosphere packaging (MAP) is a preservation technique currently used by the fresh-cut fruit industry. Fruit quality may vary according to the concentration of oxygen (O2 ) in the packaging. However, there is no published research on the effects of a pure O2 modified atmosphere in the packaging of fresh-cut pineapple. There are also no comparative studies of the differences between pure O2 and conventional low O2 MAP on the quality of fresh-cut pineapple. Materials and methods. Pineapple slices were sealed with a tray sealer using a polyethylene (PE) / polypropylene (PP) composite film and one of the following atmosphere treatments: (4% O2 + 5% CO2 ), (100% O2 ), and ambient air (control). We evaluated the effects on quality and microbial spoilage of fresh-cut pineapple. Results and discussion. Both modified atmosphere treatments delayed decreases in firmness, soluble solid contents (SSC), reducing sugar, and ascorbic acid. Pineapple slices packaged in pure O2 contained lower amounts of sugar and ascorbic acid and displayed more browning than the slices in the low O2 concentration. Additionally, both modified atmosphere treatments strongly delayed the growth of microorganisms. Aerobic bacteria, yeast and mold levels in pineapple slices packaged in pure O2 were higher than those packaged with the low O2 atmosphere during long-term storage. Conclusion. Modified atmosphere packaging using low O2 concentration (4% O2 + 5% CO2 ) was better able to maintain the quality of fresh-cut pineapple than packaging with pure O2 atmosphere.

Dai Nippon Printing Co., Ltd Medi·Ca CC for Enumeration of Coliform Bacteria.

A ready-made dry medium method for coliform count, the Medi·Ca CC method, was compared to the Violet Red Bile Agar method (Bacteriological Analytical Manual, Chapter 4, Enumeration of Escherichia coli and the Coliform Bacteria, Section G) for nine raw foods from four food categories: raw ground pork, raw lamb, raw ground chicken, raw tuna fillet, raw salmon fillet, raw shrimp, fresh peeled banana, fresh cut pineapple, and fresh cut apple. The 95% confidence interval for the mean difference between the two methods at each contamination level for seven matrixes from all four categories fell within the range of -0.50 to 0.50, and no statistical difference was observed at all three contamination levels for four matrixes from three categories. These results demonstrated that the Medi·Ca CC method is a reasonable alternative to the reference method for raw meat, raw poultry, raw fish, and fresh fruits.

Characterising and tracking deterioration patterns of fresh-cut fruit using principal component analysis – Part I

Principal component analysis (PCA) was used to characterise quality deterioration patterns in fresh-cut pineapple, strawberry, kiwifruit and cantaloupe melon during storage. Twenty-seven physiological, biochemical, microbial and sensory attributes, reported as indices of quality, were used to successfully characterise and track deteriorative changes. Freshness for all fruit was characterised by PCA as excellent visual appearance, aroma and firmness. Deterioration was characterised, for the most part, by increased tissue breakdown (exudate and cell permeability levels), firmness loss, increased off-odour development, colour loss (browning and translucency) and high microbial counts. Effects of cultivar and geographic origin were apparent in some fruit. PCA has the potential to track the effects of intrinsic and extrinsic factors of deterioration during storage and could form the basis of future strategies to optimise quality.

Antimicrobial and aromatic edible coating on fresh-cut pineapple preservation

The present research aimed to develop an edible coating incorporated with mint essential oil, evaluate its effectiveness in inhibiting in vitro microbial development, and improve both quality and shelf-life of fresh-cut pineapple. Mint essential oil-containing edible coatings showed in vitro antimicrobial efficiency against Escherichia coli and Salmonella Enteritidis. Titratable acidity, pH, and texture were not affected (P&gt;0.05) by coating or storage time. Mass loss was not higher than 1.0% after the 6th day of storage. No effect of storage time and coating on total soluble solids was observed. Mint essential oil-containing coatings inhibited the growth of yeasts and molds in fresh-cut pineapple. Compared to uncoated and control-coated samples, mint essential oil-containing coatings lessened psychrotrophic bacteria counts throughout storage. Counts of thermotolerant coliforms were not higher than 3.0MPN·g-1 in all treatments, whereas no Salmonella sp. was detected during the 6-day storage. Mint essential oil provided a strong flavor to the fruit, as shown by sensory evaluations.

Effects of Gellan-Based Edible Coating on the Quality of Fresh-Cut Pineapple During Cold Storage

The effects of gellan-based [gellan gum 0.56 % (w/v), glycerol 0.89 % (w/v) and sunflower oil 0.025 % (w/v)] edible coating on the respiration rate, physico-chemical properties and microbiological and sensory quality of fresh-cut pineapple during 16 days of storage (5 ± 1 °C, 85 ± 10 % RH) were evaluated. Uncoated fresh-cut pineapple was stored under the same condition and served as the control. For cross-linking reaction which was necessary for gel formation of gellan gum, a 2 % (w/v) calcium chloride solution that contained 1 % (w/v) ascorbic acid and 1 % (w/v) citric acid (as antibrowning agents) was used. The results obtained show that the respiration rate and weight loss of gellan-based coated samples were significantly (p 0.05) differences were found among total plate counts and yeast and mould counts for coated and uncoated samples. Total plate counts and yeast and mould counts for coated and uncoated samples reached 106 CFU/g (limit of shelf life acceptance for fruit-based products recommended by the Institute of Food Science and Technology in the UK) after 12 days of storage at 5 °C. In addition, the scores for all sensory characteristics at day 12 were significantly (p < 0.05) higher in coated samples as compared to control. Therefore, the results obtained in this study indicate that gellan-based edible coating formulation has the potential to maintain the quality of fresh-cut pineapple during low-temperature storage for about 12 days.

Fresh-cut pineapple as a new carrier of probiotic lactic acid bacteria.

Due to the increasing interest for healthy foods, the feasibility of using fresh-cut fruits to vehicle probiotic microorganisms is arising scientific interest. With this aim, the survival of probiotic lactic acid bacteria, belonging to Lactobacillus plantarum and Lactobacillus fermentum species, was monitored on artificially inoculated pineapple pieces throughout storage. The main nutritional, physicochemical, and sensorial parameters of minimally processed pineapples were monitored. Finally, probiotic Lactobacillus were further investigated for their antagonistic effect against Listeria monocytogenes and Escherichia coli O157:H7 on pineapple plugs. Our results show that at eight days of storage, the concentration of L. plantarum and L. fermentum on pineapples pieces ranged between 7.3 and 6.3 log cfu g−1, respectively, without affecting the final quality of the fresh-cut pineapple. The antagonistic assays indicated that L. plantarum was able to inhibit the growth of both pathogens, while L. fermentum was effective only against L. monocytogenes. This study suggests that both L. plantarum and L. fermentum could be successfully applied during processing of fresh-cut pineapples, contributing at the same time to inducing a protective effect against relevant foodborne pathogens.

EFFECT OF LIMONENE INCORPORATION INTO GELLAN-BASED EDIBLE COATING ON THE CHANGES IN MICROBIOLOGICAL AND SENSORY CHARACTERISTICS OF FRESH-CUT PINEAPPLE DURING COLD STORAGE

The microbiological stability of fresh-cut fruits is still one of the most challenging problems in the fresh-cut fruit industry. Essential oils have been used recently as natural antimicrobial agents. Incorporating natural antimicrobial agents into edible coatings provides a novel way to increase the shelf life and to maintain the quality of fresh-cut fruits. The aim of this work was to study the effect of different concentrations of limonene (0.1, 0.3 and 0.5% w/v) incorporated into gellan-based edible coating on the microbiological stability and sensory characteristics of fresh-cut ‘Josapine’ pineapple during 16 days storage at 10±1°C; 65±10% RH. Coated fresh-cut pineapple without limonene and uncoated fresh-cut pineapple were stored under the same conditions and served as the controls. The gellan-based edible coating formulation was an aqueous solution of gellan gum (0.56% w/v), glycerol (0.89% w/v) and sunflower oil (0.025% w/v). The results obtained show that total plate count increased significantly (p<0.05) during storage for all treatments. Total plate count for edible coating formulations with 0.3 and 0.5% (w/v) limonene were significantly (p<0.05) lower than other formulations. There was no significant difference between total plate count for gellan-based coating without limonene and uncoated samples. The results for sensory evaluation showed that the scores for taste and overall acceptability were significantly (p<0.05) lower in gellan-based coated samples with 0.5% (w/v) limonene in comparison with other coated samples. Therefore, results of this study indicate that gellan-based edible coating formulation incorporated with 0.3% (w/v) limonene significantly (p<0.05) reduced total plate count and maintained the sensory characteristics of fresh-cut pineapple.

IMPROVEMENT OF HANDLING MACHINES FOR COMMERCIAL OPERATIONS OF FRESH-CUT PINEAPPLE

Fresh-cut fruits is a growing sector of the food industry in many parts of the world. Its success depends greatly on several factors, especially the quality and consumers’ confidence. Products are prepared in ready-to-eat form whilst retaining the organoleptic characteristics of fresh fruits in terms of aroma, flavour, taste, colour and texture. Appropriate method of preparation is obligatory in order to maintain their freshness. The preparation involves cleaning, washing, trimming, coring, slicing and other related steps of which many of these processes hasten the products to perish. Uniformity, time and labour consumption have always been raised by the cut fruit operators especially for the bulk handling. Imported machines for the processing of cut fruits are available in the markets. However, high cost and suitability of the machine to the local fruits hinder the active use of the machine especially by small scale fruit operators. Intensive research had been conducted in developing a suitable mechanized system for commercial handling of fresh cut pineapple comprising of stalk and crown cutter, skin peeler, flesh slicer and centrifugal drip dryer. The newly developed machines were successfully tested during the recent commercial handling trial of fresh-cut pineapple to Perth, Australia. Uniform cutting of the stalk and crown had contributed to the stability of the fruits upon being subjected to skin peeler machine. The skin peeler machine was integrated with blade cutter which cut the flesh into two portions. Uniform semicircle cutting shape and size will be produced upon subjecting the individual portion to the flesh slicer machine. A centrifugal drip dryer machine facilitates in removing the excess water after the cut pieces were subjected to pre-treatment solutions before undertaking the packing process.