Search

The large amount of unutilised pineapple wastes produced every year in tropical countries, particularly in Thailand, adds to the existing environmental pollution problems of the country. This study investigated the utilisation of pineapple wastes to treat another form of waste (sludge) from wastewater treatment facilities in Thailand. Laboratory scale studies were carried out to determine the potential of using naturally fermented raw liquid from pineapple wastes as a source of citric acid in the extraction of Cr, Cu, Pb, Ni and Zn from anaerobically digested sewage sludge. Results of the leaching study revealed its effectiveness in extracting Zn (at 92%) at pH 3.67 and a short leaching time of only 2 h, and Ni at almost 60% removal at the same leaching time. Chromium removal was also high at almost 75% at a longer leaching time of 11 days. Variation in metal removal efficiencies may also be attributed to the forms of metals in sludge, with metals predominantly in the exchangeable and oxidisable phases showing ease of leachability (such as Zn). Compared to citric acid, at pH approaching 4.0, naturally fermented raw liquid seemed to be more effective in the removal of Zn and Cu at the same leaching time of 2 h, and Cr at a longer leaching time of 11 days. The pineapple pulp, which is a by-product of the process, can still be used as animal feed because of its high protein content.

This study proposed a novel waste utilization bioprocess for production of lactic acid and fungal biomass from waste streams by fungal species of Rhizopus arrhizus 36017 and R. oryzae 2062. The lactic acid and fungal biomass were produced in a single-stage simultaneous saccharification and fermentation process using potato, corn, wheat and pineapple waste streams as production media. R. arrhizus 36017 gave a high lactic acid yield up to 0.94-0.97 g/g of starch or sugars associated with 4-5 g/l of fungal biomass produced, while 17-19 g/l fungal biomass with a lactic acid yield of 0.65-0.76 g/g was produced by the R. oryzae 2062 in 36-48 h fermentation. Supplementation of 2 g/l of ammonium sulfate, yeast extract and peptone stimulated an increase in 8-15% lactic acid yield and 10-20% fungal biomass.

An investigation was made of the respiratory properties and the role of the mitochondria isolated from one phosphoenolpyruvate carboxykinase (PCK)-CAM plant Ananas comosus (pineapple) in malate metabolism during CAM phase III. Pineapple mitochondria showed very high malate dehydrogenase (MDH), and low malic enzyme (ME) and glutamate-oxaloacetate transaminase (GOT) activities. The mitochondria readily oxidized succinate and NADH with high rates and coupling, while they only oxidized NADPH in the presence of Ca(2+). Pineapple mitochondria oxidized malate with low rates under most assay conditions, despite increasing malate concentrations, optimizing pH, providing cofactors such as coenzyme A, thiamine pyrophosphate, and NAD(+), and supplying individually external glutamate or GOT. However, providing glutamate and GOT simultaneously strongly increased the rates of malate oxidation. The OAA easily permeated the mitochondrial membranes to import into or export out of pineapple mitochondria during malate oxidation, but the mitochondria did not consume external Asp or alpha-KG. These results suggest that OAA played a significant role in the mitochondrial malate metabolism of pineapple, in which malate was mainly oxidized by active mMDH to produce OAA which could be exported outside the mitochondria via a malate-OAA shuttle. Cytosolic GOT then consumed OAA by transamination in the presence of glutamate, leading to a large increase in respiration rates. The malate-OAA shuttle might operate as a supporting system for decarboxylation in phase III of PCK-CAM pineapple. This shuttle system may be important in pineapple to provide a source of energy and substrate OAA for cytosolic PCK activity during the day when cytosolic OAA and ATP was limited for the overall decarboxylation process.

Background and Aims: Plants with crassulacean acid metabolism (CAM) can be divided into two groups according to the major carbohydrates used for malic acid synthesis, either polysaccharide (starch) or monosaccharide (hexose). This is related to the mechanism and affects energy metabolism in the two groups. In Kalanchoë pinnata and K. daigremontiana, which utilize starch, ATP-dependent phosphofructokinase (tonoplast inorganic pyrophosphatase) activity is greater than inorganic pyrophosphate-dependent phosphofructokinase (tonoplast adenosine triphosphatase) activity, but the reverse is the case in pineapple (Ananas comosus) utilizing hexose. To test the hypothesis that the energy metabolism of the two groups differs, day-night changes in the contents of ATP, ADP, AMP, inorganic phosphate (Pi), phosphoenolpyruvate (PEP) and inorganic pyrophosphate (PPi) in K. pinnata and K. daigremontiana leaves and in pineapple chlorenchyma were analysed., Methods: The contents of energy-rich compounds were measured spectrophotometrically in extracts of tissue sampled in the light and dark, using potted plants, kept for 15 d before the experiments in a growth chamber., Key Results: In the three species, ATP content and adenylate energy charge (AEC) increased in the dark and decreased in the light, in contrast to ADP and AMP. Changes in ATP and AEC were greater in Kalanchoë leaves than in pineapple chlorenchyma. PPi content in the three species increased in the dark, but on illumination it decreased rapidly and substantially, remaining little changed through the rest of the light period. Pi content of Kalanchoë leaves did not change between dark and light, whereas Pi in pineapple chlorenchyma increased in the dark and decreased in the light, and the changes were far greater than in Kalanchoë leaves. Light-dark changes in PEP content in the three species were similar., Conclusions: These results corroborate our hypothesis that day-night changes in the contents of energy-rich compounds differ between CAM species and are related to the carbohydrate used for malic acid synthesis.

A cDNA fragment encoding the cysteine protease inhibitor, cystatin, was cloned from pineapple (Ananas comosus) stem. This clone was constructed in a fusion vector and was easily over-expressed in Escherichia coli; satisfactory over-expression of non-fusion cystatin was achieved after an additional start codon was inserted prior to its coding sequence. Both recombinant cystatins were predominately found in the soluble fraction of the cell extract, and were demonstrated to be functionally active in a reverse zymographic assay. The fusion and non-fusion cystatins were separately purified to homogeneity via a His-tag or papain-coupling affinity column. Effective inhibitory activity against papain was detected with both the fusion and non-fusion cystatins with comparable K(i) values of 1.18 x 10(-10) M and 9.53 x 10(-11) M, respectively. The recombinant cystatins were found to be thermally stable up to 60 degrees C. Inhibition of the endogenous protease activity in minced fish muscle revealed that the recombinant pineapple cystatins might be an adequate stabilizer to prevent protein degradation during industrial food processing.

Third-stage larvae were used as antigen in the diagnosis of gnathostomiasis in Western blot analysis. Normally, the larvae were obtained from digestion of eel's liver (Fluta alba) by the enzyme pepsin. We used pineapple juice (Ananus comosus) instead of enzyme pepsin in harvesting Gnathostoma spinigerum third-stage larvae. The difference in recovered larvae numbers, between pineapple juice and pepsin, were not statistically significantly different (p>0.05). The larvae from pepsin and pineapple juice digestion were cultivated on BME for 7 days; the survival rates were not significantly different (p>0.05). Thus, pineapple juice is another enzyme of choice for recovering Gnathostoma spinigerum third-stage larvae.

Penicillium funiculosum Thom. was consistently isolated from pineapple-infected fruitlet (black spots). Polyphenol oxidase, peroxidase, and laccase activities were determined in extracts from contiguous and infected fruitlets. Healthy fruitlets showed a rather high level of polyphenol oxidase (optimum pH 7.0), and this activity was tremendously increased (X 10) in contiguous infected fruitlets. Furthermore, infected fruitlets also exhibited laccase activity (optimum pH 4.0), while peroxidase was rather constant in both fruitlets. Browning reactions were attributed to qualitative and quantitative modifications of the enzymatic equipment (polyphenol oxidase and laccase) (p < 0.0001). In infected fruiltets, sucrose and L-malic acid were present at significantly lower amounts than in healthy ones, likely owing to fungal metabolism (p < 0.0001), whereas cell wall material was three times higher, which could be viewed as a defense mechanism to limit expansion of the mycelium.

Canned pineapple syrup, a food processing waste, was utilized as a substrate for lactic acid production by Lactococcus lactis. To improve the utilization of sucrose from the syrup, grape invertase from grape juice derived from wine production was used for sucrose hydrolysis. The highest lactic acid concentrations achieved were 20 and 92 g l-1 from 20 and 100 g total sugars l-1, respectively, without a lag period for sucrose consumption.