Improving the quality of fresh‐cut pineapples with ascorbic acid/sucrose pretreatment and modified atmosphere packaging

The effects of pretreatment and modified atmosphere packaging (MAP) on the quality of fresh‐cut pineapples stored at 4°C were evaluated for 7 days. The pretreatment was conducted by immersing the pineapple slices in a solution containing 0.25% ascorbic acid and 10% sucrose for 2min. MAP contained 4% oxygen, 10% carbon dioxide and 86% nitrogen. Both the pretreatment and MAP could reduce the respiration rate, ethylene production, textural and colour deteriorations, as well as the overall sensory deterioration in fresh‐cut pineapples. MAP could restrain the growth of microbes, but the pretreatment showed little effect. Fresh‐cut pineapples exhibited wet surface and off‐flavour after storage at 4°C for 3 days, while the pretreatment and MAP maintained the quality for up to 7 days. Copyright © 2007 John Wiley & Sons, Ltd.     

Nitrogen and potassium requirement of pineapple in relation to irrigation in Nigeria

The investigation studied the effect of fertilization with four nitrogen levels (0, 100, 150 and 200 kg/ha), four potassium levels (0, 100, 150 and 200 kg/ha) and four irrigation treatments (0, 3, 7 and 14-day interval) on the growth and yield of smooth Cayenne pineapples. Increasing irrigation frequency increased growth parameters of number of leaves, D-leaf length and days to 50% flowering. Fruit weight was highest at N = 150 kg/ha, K = 200 kg/ ha and irrigation once a week. Higher N levels (beyond 150 kg/ha) applied after the plant crop has been harvested did not further enhance yields of the ratoon crop. For K = 200 kg/ha potential and harvested yields were reduced in all irrigation treatments when N > 150 kg/ha.     

Protective effect of cysteine—HCl on vitamin C in dehydrated pickled/candied pineapples and guava

Dehydrated pickled/candied guava and pineapples pretreated with 0.24 g kg^?1 cysteine hydrochloride (cys-HCl) had increased ascorbic acid retention and reduced colour change during storage. Dehydrated pineapples pretreated with cys-HCl had two to three times the ascorbic acid content of control or metabisulphite-treated products. The rate of ascorbic acid loss for all products stored at room temperature were similar, showing that cys-HCl was only protective towards ascorbic acid during the preparation and dehydration process. Candied dehydrated guava showed less colour change and higher ascorbic acid retention (about 57%) than pickled guava (ascorbic acid retention about 30%). Cys-HCl was quite effective in reducing browning of candied pineapples but not pickled pineapples. Sensory evaluation showed that candied guava pretreated with 0.24 g kg^?1 cys-HCl was generally preferred over the other dehydrated guava products. Cys-HCl-treated candied pineapples had the best flavour compared with all other dehydrated pineapple products. Cys-HCl appeared to favour conversion of glucose to fructose during storage of dehydrated pineapples.     

The post harvest sensory and chemical characteristics of cold‐stored pineapples pretreated with different Fruitone concentrations

The effects of Fruitone CPA [2‐(3‐chlorophenoxy)propionic acid] (0‐44 ppm) on post‐harvest storage, chemical characteristics and sensory evaluation of pineapples for fresh consumption after storage at 10 ± 1 °C were studied. Pre‐harvest Fruitone treatment beneficially affected the physical characteristics of pineapples, namely increased fruit weight, reduced texture loss, reduced crown size and delayed ripening, but adversely affected their chemical characteristics. Almost all parameters analysed (total soluble solid, titratable acidity, pH and sugars) showed that Fruitone concentrations between 35.2 and 44 ppm were most effective in delaying the ripening of pineapples compared to other concentrations. At these concentrations, Fruitone significantly (P < 0.05) reduced the total soluble solid and pH, but significantly (P < 0.05) increased the titratable acidity. Fruitone treatment was effective in maintaining the TSS and reduced the fluctuation of sugar and the sugar–acid ratio during storage and between fruits. Sensory scores showed that there was a slight increase in the score for odour after 3 weeks of storage between Fruitone‐treated pineapples and control pineapples, while all other sensory attributes (sourness, sweetness, flavour and overall acceptability) were insignificantly different. All sensory attributes correlated positively with pH and sucrose at low concentrations of Fruitone (0–8.8 ppm and 0–26.4 ppm, respectively); with glucose at intermediate Fruitone concentration (17.6–26.4 ppm); with total soluble solid at higher Fruitone concentrations (35.2–44 ppm); and with sugar–acid ratio at all concentrations (except at 44 ppm Fruitone). Copyright © 2006 Society of Chemical Industry     

Comparison of reusable and single‐use plastic and paper shipping containers for distribution of fresh pineapples

This paper presents the effects of different packaging systems and fruit orientation on bruising and pre‐cooling time of pineapples during distribution. The package types studied were reusable plastic containers, single‐use paper corrugated containers and plastic foam containers (FCs). Simulated vibration tests were performed to evaluate the shipping containers on their protective performances. After the vibration tests, pineapples were evaluated for bruise damage and decay during storage for 5 days. Pineapple fleshes were also evaluated for bruise volume and changes in colour, firmness, total soluble solids content (TSS) and titratable acidity (TA) after storage of 5 days. Bruise damage was more intense as the storage time increased. Package types had significant effects (p ≤ 0.05) on bruise damage of pineapples. The corrugated containers showed the best protective performance for pineapples, while the FCs showed the worst. The corrugated containers with paperboard partitions showed the lowest damage levels as compared to other package types studied. Foam‐net cushion reduced bruise damage of pineapples. L values and firmness of pineapple flesh were highly associated with degree of bruising. The results suggested that slight bruising on the skin may signify severe bruising on the flesh and bruising accelerated decay in pineapples. Orientation did not show a significant effect (p ≤ 0.05) on bruising. The highest pre‐cooling rates were observed in the reusable plastic containers, while the slowest rates were observed in the single‐use paper containers. The results indicated that careful handling in the proper packaging with optimum cushion can minimize bruise damage and decay of pineapples after shipments. Copyright © 2007 John Wiley & Sons, Ltd.     

Enzymatic and Mechanical Extraction of Virgin Coconut Oil

The effect of different processing methods namely enzymatic method using crude protease extract (CPE) from overripe pineapple, microwave‐assisted extraction (MAE) and ultrasound‐assisted extraction (UAE) methods on the recovery yield of virgin coconut oil (VCO) is evaluated. The physicochemical properties of VCOs namely color, iodine value (IV), refractive index, saponification value, moisture content, free fatty acid, p‐anisidine value, lipid peroxidation, fatty acid composition, triacylglycerol (TAG) composition, melting and crystallization profile are compared. The total phenolic compounds and scavenging activity of the extracted VCOs are also examined. Results reveal that enzymatic approach exhibits the highest VCO yield (77.7% ± 0.38) at 50 °C for 2 h, followed by MAE (58.6%±0.07), control without enzyme (24.1%±0.19) and UAE (24.1%±0.12). The physicochemical properties of the VCOs extracted are found to conform to APCC standards established except IV. The antioxidant activity of VCO extracted with CPE shows no significant difference with MAE and UAE methods (p > 0.05). Lauric acid appears to be the most abundant fatty acid detected in all VCO samples. Similar exotherms and endotherms are observed in both melting and crystallization profiles with two distinct peaks exhibited. The TAG compositions of the extracted VCOs are mainly LaLaLa, LaLaM, CLaLa, CCLa, and LaMM (C = Capric acid; La = Lauric acid; M = Myristic acid). Practical Applications: The results obtained from this study indicate that VCO extraction using CPE from overripe pineapple is feasible. The enzymatic extraction protocol presented here would be useful for VCO production at industrial scale with a promising oil yield.     

Ventilated tunnel solar dryers for small-scale farmers communities: Theoretical and practical aspects

The design of so-called “ventilated tunnel solar dryers" is presented in this work under theoretical and practical aspects. These dryers consist in a tunnel with a black floor and a plastic top, ventilated with fans supplied by a photovoltaic module. Along this tunnel, the air first passes through a heating part, which is product free and where the air is heated due to greenhouse effect. It then enters the second part of the dryer, the drying part, where the products to dry are spread. A rational and general design procedure based on the solving of energy and mass balance equations is developed and followed. This procedure allows designing the ventilation system and calculating the lengths of the heating and the drying parts of a dryer according to a scope statement and to design conditions insuring an efficient and homogeneous drying. Two dryers were designed, built and operated, in the frame of two development aid programs, in Cambodia and in Uganda. The fieldwork highlighted the importance of practical building and operating aspects, reported in the present paper, and of including people of the local communities in these programs. Results of field drying experiments are shown and demonstrate the validity of the design procedure. In particular, the validity of the energy balance equations at the basis of the procedure is demonstrated.     

等离子体活化水对鲜切菠萝品质的影响

鲜切菠萝极易被腐败菌污染,造成品质下降,货架期缩短.为在不引起鲜切菠萝品质劣变的前提下,有效杀灭腐败菌,延长货架期,该研究首先采用大气压低温等离子体处理蒸馏水得到等离子体活化水(plasma-activated water,PAW),再利用PAW对鲜切菠萝进行清洗,分别考察PAW的制备时间、制备功率以及清洗时间对鲜切菠...     

Efficiency of pre-process anoxia treatment on quality of fresh-cut pineapples cv. ‘Phulae’ during storage

The aim of this study was to investigate the competency of pre-process anoxia treatment on physicochemical quality of fresh-cut pineapples cv. ‘Phulae’ during storage. The fruits were kept in anoxia atmosphere (N₂) for 16 h before processing. The fruits were processed immediately after treatment (G1) and after storage at 13 °C for 6 days (G2). Anoxia treatment delayed the weight loss and had no effect on the L* value of both G1 and G2 fresh-cut pineapples. The yellowness (b*) value of G1 fresh-cut pineapple was maintained by anoxia. The PPO activity of anoxia-treated G1 and G2 fresh-cut pineapples was lower than that of untreated fresh-cut fruits (control). Total sugars contents of both G1 and G2 anoxia-treated fresh-cut pineapples trended to be higher than that of control samples. Anoxia had no influence on the total ascorbic acid content during storage. The increases in total bacteria and yeast of both G1 and G2 fresh-cut pineapples were retarded by anoxia. In conclusion, anoxia is a feasible alternative to maintaining quality and delaying microbial increases in fresh-cut pineapples during storage.