Liquid Endosperm Research Articles

Wheat wounding-responsive HD-Zip IV transcription factor GL7 is predominantly expressed in grain and activates genes encoding defensins.

Several classes of transcription factors are involved in the activation of defensins. A new type of the transcription factor responsible for the regulation of wheat grain specific defensins was characterised in this work. HD-Zip class IV transcription factors constitute a family of multidomain proteins. A full-length cDNA of HD-Zip IV, designated TaGL7 was isolated from the developing grain of bread wheat, using a specific DNA sequence as bait in the Y1H screen. 3D models of TaGL7 HD complexed with DNA cis-elements rationalised differences that underlined accommodations of binding and non-binding DNA, while the START-like domain model predicted binding of lipidic molecules inside a concave hydrophobic cavity. The 3'-untranslated region of TaGL7 was used as a probe to isolate the genomic clone of TdGL7 from a BAC library prepared from durum wheat. The spatial and temporal activity of the TdGL7 promoter was tested in transgenic wheat, barley and rice. TdGL7 was expressed mostly in ovary at fertilisation and its promoter was active in a liquid endosperm during cellularisation and later in the endosperm transfer cells, aleurone, and starchy endosperm. The pattern of TdGL7 expression resembled that of genes that encode grain-specific lipid transfer proteins, particularly defensins. In addition, GL7 expression was upregulated by mechanical wounding, similarly to defensin genes. Co-bombardment of cultured wheat cells with TdGL7 driven by constitutive promoter and seven grain or root specific defensin promoters fused to GUS gene, revealed activation of four promoters. The data confirmed the previously proposed role of HD-Zip IV transcription factors in the regulation of genes that encode lipid transfer proteins involved in lipid transport and defence. The TdGL7 promoter could be used to engineer cereal grains with enhanced resistance to insects and fungal infections.

Altered development, quality and sink strength in asynchronous maturing fruits produced from the two-sequence female flowers inflorescence/cluster of ‘Yu Her Pau’ litchi

‘Yu Her Pau’ is one of the most dominant litchi (Litchi chinensis Sonn.) cultivars grown in Taiwan and China. However, the extremely large inflorescences often result in the production of early- and late- flowering female flowers (“two-sequence inflorescence”), thereby leading to the production of late-maturing fruit within the same cluster. This asynchronous maturity, often being regarded as a nuisance by growers and the impact of this trait requires further clarity. To document the alteration of growth and characteristics of fruits that mature asynchronously inside a cluster, 10-year-old field grown plants were used in the present study. Four categories of fruit: early- or late-maturing fruit in the presence of single cluster; and early- or late-maturing fruit in the presence of two-sequence cluster on trees were selected. The fruit growth curves and patterns, liquid endosperm retention in the embryo sac, primary (apparent) sink strength quantity and harvested quality were analyzed. The accumulated heat unit from fruit set to maturity was estimated. Flowering dates were noted to be three weeks apart, whereas harvest dates were noted to be only one week apart between the early- and late-maturing fruit because of the two-week longer maturity period of the early-maturing fruit. All categories of fruit exhibited single sigmoid curve and have commercial value at harvest. Early-maturing fruit from the early-maturing two-sequence inflorescence were approximately 50% heavier and matured two weeks earlier than the late-maturing fruit and exhibited significantly higher quality. The larger fruit from the early-maturing two-sequence clusters was associated with smaller seeds, higher absolute and relative fruit growth rates, longer fruit development periods in response to lower air temperatures pertaining at that time, greater primary sink strength quantity, longer retention of liquid endosperm, and higher accumulated heat units that were amassed during the pulp growth stage. In the meantime, the earlier dissipating of liquid endosperm in late-maturing fruit and in early-maturing two-sequence fruit was associated with decreased seed size. Late-maturing fruit in two-sequence clusters increased the primary sink strength quantity of early-maturing fruit in the same cluster. The results from our research should prompt a re-assessment of the physiological significance of the second-sequence of female flowers in litchi cultivars with extremely large inflorescence.

Decimal reduction energies of UV-C-irradiated spoilage yeasts in coconut liquid endosperm

The ultraviolet-C (UV-C) decimal reduction energy (DUV-C) values of 17 spoilage yeasts and their composited inoculum were determined in coconut liquid endosperm (pH 5.26, 5.8 °Brix, 0.04% malic acid, 0.17% w/v insoluble solids). Growth kinetic parameters of all the test yeast strains were first established to standardize the growth stage of the cells prior to inactivation studies. Approximately 4.0 to 5.0 log CFU/mL cells in the mid-stationary growth phase (30.3 to 39.9 h, 25 °C) were suspended in 4 mL turbulent flowing juice and subjected to UV-C irradiation at a surface irradiance range of 3.42 to 4.99 mW/cm2. Survivor populations after exposure to predetermined UV-C energy were enumerated, and were used to derive the DUV-C values using the linear regression and Baranyi and Roberts (1994) model fitting. Results show that the yeast strains exhibited either log-linear or biphasic inactivation behavior with inactivation lag. The most UV-C resistant spoilage yeast was found to be Cryptococcus albidus (LJY1) with DUV-C values of 122.72 and 214.89 mJ/cm2 determined from linear regression and model-fitting, respectively. The least UV-C resistant was Torulaspora delbrueckii (LYJ5) with a DUV-C of 17.34 (linear regression) and 17.35 mJ/cm2 (model-fitting). The DUV-C values determined from the model fitting were generally greater than those calculated from linear regression, although only those determined for C. albidus were significantly different. To the investigators' knowledge, this is the first report of the UV-C inactivation kinetic parameters of Kluyveromyces marxianus, Trichosporon cutaneum, Pichia anomala, and Meyerozyma guilliermondii and C. albidus in coconut liquid endosperm. The results of this study can be used in the establishment and validation of UV-C process schedules for coconut liquid endosperm and other similar commodities.

Effects of suboptimal growth conditions on the subsequent UV-C resistance of Listeria monocytogenes in coconut liquid endosperm and apple juice

This study determined the ultraviolet-C (UVC) resistance of Listeria monocytogenes in coconut liquid endosperm and apple juice after previous exposures to suboptimal growth conditions. L. monocytogenes 1/2c and 4b strains were individually exposed to gradual acidification (final pH 4.5), desiccation (aw 0.96), heating (40 °C), and all their simultaneous combinations. Results showed that regardless of prior growth conditions and fruit beverage suspending medium, L. monocytogenes exhibited log-linear inactivation behavior. The UV-C energy dose necessary to reduce microbial population by 1 log cycle (DUV-C) varied across growth conditions and between fruit beverages. Regardless of growth condition, L. monocytogenes exhibited greater resistance in apple juice. In coconut liquid endosperm, the greatest UV-C resistance was observed in cells previously exposed to acidification and heat (A+H) (DUV-C 37.32 mJ/cm2), while cells previously exposed to acidification and desiccation (A+D) exhibited the greatest resistance to UV-C in apple juice (DUV-C 726.76 mJ/cm2). L. monocytogenes exhibited least UV-C resistance in coconut when previously exposed to heating (DUV-C 25.40 mJ/cm2), while exposure to A+H resulted in least UV-C resistance when suspended in apple juice (DUV-C 298.81 mJ/cm2). These results suggest that in addition to intrinsic suspending medium properties, implicit microbial physiology also affect the efficacy of UV-C treatment.

Individual and combined efficacies of mild heat and ultraviolet-c radiation against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in coconut liquid endosperm

This study determined the inactivation kinetic parameters of selected pathogens in heat, ultraviolet-C and combined heat-UV-C treated coconut liquid endosperm. Separate cocktails of Escherichia coli O157:H7, Salmonella enterica serovars, and Listeria monocytogenes strains were inoculated into coconut liquid endosperm (pH 5.15, TSS 4.4oBx, TA 0.062% malic acid, extinction coefficient (ε) at 254 nm of 0.0154 cm−1) for inactivation studies. Result showed that all organisms generally exhibited a log-linear heat inactivation behavior (R2 0.81–0.99). The E. coli O157:H7 cocktail (D55 = 19.75 min, D57 = 10.79 min, D60 = 3.38 min, and D63 = 0.46 min) was found to be significantly more resistant (P > 0.05) than the tested cocktail of L. monocytogenes (D55 = 11.68 min, D57 = 4.53 min, D60 = 1.82 min and D63 = 0.26 min) and S. enterica cocktail (D55 = 3.08 min, D57 = 2.60 min, D60 = 0.89 min and D63 = 0.25 min). Despite the differences in DT values, computed z values for L. monocytogenes cocktail (5.12 ± 0.43 °C) and E. coli O157:H7 cocktail (4.95 ± 0.12 °C) were not significantly different (P > 0.05), but were both significantly (P < 0.05) lower than that of S. enterica cocktail (7.10 ± 0.15 °C). All test organisms also exhibited a generally log-linear UV-C inactivation behavior (R2 0.90–0.99) with E. coli O157:H7 cocktail (DUV-C = 25.26 mJ/cm2) demonstrating greatest resistance to UV-C than S. enterica (DUV-C = 24.65 mJ/cm2) and L. monocytogenes (DUV-C = 17.30 mJ/cm2) cocktails. The D55 values of each organism cocktail were used to calculate for the 3-log reduction heating process schedules, during which UV-C treatments were simultaneously applied. Lethal rates (F values) calculations in the combined processes revealed that within the 3-log reduction heating processes, co-exposure of UV-C resulted in 5.62 to 6.20 log reductions in the test organism populations. Heating caused 69.3, 97.2, and 67.4% of the reduction in E. coli O157:H7, S. enterica and L. monocytogenes cocktails, respectively. These results can be used as baseline data in the establishment of mild heat treatment in combination with UV-C process schedules for coconut liquid endosperm and other similar products.

GENETIC DIVERSITY ASSESSMENT AMONG TALL COCONUT PALM

ABSTRACT The tall coconut (Cocos nucifera L.) has great socioeconomic importance in Brazil and was first introduced on the coast of the north-eastern region, where it has been exploited in a semi-extractivist manner. The goal of this study was to quantify the genetic divergence between accessions introduced and preserved at the International Coconut Genebank for Latin America and the Caribbean, estimate the efficiency of descriptors used in the discrimination of the accessions, and indicate the essential descriptors for the activities of characterisation and evaluation. The accessions used were: Polynesia Tall; Tonga Tall; West African Tall; Rennel Tall; Rotuma Tall; Vanuatu Tall; Malayan Tall and Brazilian Tall Praia-do-Forte. Thirty-five quantitative descriptors recommended for the species were used. Genetic divergence was estimated by the Mahalanobis’s generalised distance and the cluster analysis was performed using the unweighted pair group method with arithmetic mean (UPGMA). The relative importance of the descriptors was measured according to Singh and Jolliffe’s methods, and the variables were selected taking into consideration the matching information in the two methods, eliminating those that were discarded in the two procedures. The agronomic characteristics indicated that the first canonical variable explained 90.25% of total variance. The most efficient descriptors for detecting the genetic divergence were: fruit equatorial circumference; nut polar and equatorial circumference; quantity of liquid endosperm; total fruit weight; nut weight; stem height; girth of stem at 1,5m height; number of leaflets; and number of bunches. The most dissimilar accessions according to the agronomic characteristics were Rotuma Tall and West African Tall, which can be primarily indicated as genitors for the formation of segregating populations in breeding programmes.

Previous stress exposures influence subsequent UV-C resistance of Salmonella enterica in coconut liquid endosperm

This study determined the effects of prior exposures to stresses commonly encountered by cells in food production and processing environments on the subsequent UV-C inactivation rates of Salmonella enterica in coconut liquid endosperm. Seven different strains of S. enterica were separately exposed to individual stresses such as gradual acidification (final pH 4.5), abrupt desiccation (aw 0.96), or heat stress at 40 °C for 24 h, after which the test strains were cocktailed and subjected to UV-C challenge. Cells were also exposed to all possible combinations of the individual stresses and thereafter subjected to UV-C challenge. Cells exposed to all individual and combinations of stresses exhibited 1st order, log-linear inactivation behavior (R2 0.903 to 0.998). Cells previously exposed to singular heat stress had the highest UV-C resistance (DUV-C 43.8 mJ/cm2), while cells exposed to all simultaneous pH, aw, and heat stresses had the least (DUV-C 22.5 mJ/cm2). Heterologous adaptive mechanisms were observed after S. enterica cells were exposed to acid, acid + desiccation, heat, and acid + heat, with individual heat stress exposure resulting in the significantly most UV-C resistant cells. Results obtained in this study provide baseline information on the selection of appropriate challenge organism for establishment of UV-C process schedule for coconut liquid endosperm and similar commodities.

TENDER COCONUT WATER INHIBITS THE GROWTH OF HUMAN LIVER CANCER CELL LINE HepG2

Tender Coconut Water (TCW), the liquid endosperm of young coconut fruit is not only rich in nutrients but also has bioactive phytohormones such as zeatin, kinetin and their derivatives. Naturally occurring phytohoromes have antiproliferative properties and are effective in inhibiting growth of selected cancer cell lines. According to the Center for disease Control and Prevention, in the United States of America about 21,000 men and 8,000 women are diagnosed with liver cancer every year, and approximately 12,000 men and 8,000 women die of the disease each year. Furthermore, the percentage of Americans diagnosed with liver cancer is on the rise. We evaluated the ability of TCW to prevent the growth and viability of human liver cancer cells, using HepG2 cell line as the model system. HepG2 cells were incubated with increasing concentrations of TCW in MEM media (V/V) supplemented with 5% fetal bovine serum for 3–5 days and assessed for cell viability and proliferation. TCW decreased HepG2 cell viability as demonstrated by the MTT assay. In the presence of TCW, the proliferation of the HepG2 cells was significantly decreased as measured by BrdU incorporation assay. We also show that the anchorage‐independent growth ability of HepG2 cells was severely impaired in the presence of TCW as measured by soft‐agar colony forming assay. TCW decreased the tumorigenicity of HepG2 liver cancer cell line. Our results suggest that TCW may have anti‐tumor effects in the treatment of human liver cancer.

De novo transcriptome assembly and identification of the gene conferring a “pandan-like” aroma in coconut (Cocos nucifera L.)

Thailand’s aromatic coconut (Cocos nucifera L.) is a special type of green dwarf coconut, the liquid endosperm of which is characterized by a pleasant “pandan-like” aroma due to the presence of 2-acetyl-1-pyrroline (2AP). The aim of this study was to perform a de novo assembly of transriptome from C. nucifera endosperm and to identify the gene responsible for 2AP biosynthesis. CnAMADH2 was identified as an ortholog of the rice aromatic gene and a G-to-C substitution found in exon 14 was associated with 2AP content in the aromatic green dwarf coconut accessions. The base substitution caused an amino-acid change, alanine-to-proline, at position 442 (P442A). The presence of P at this position might alter the steric conformation at the loop region and subsequently result in an unstabilized dimer conformation that could lower AMADH enzyme activity. Among AMADH/BADH protein sequences in different plant species, the P442A mutation was found exclusively in aromatic coconut. The PCR marker developed based on this sequence variation can perfectly detect the aromatic and non-aromatic alleles of the gene. This study confirms the hypothesis that plants may share a mechanism of 2AP biosynthesis. This is the first identification of the gene associated with 2AP biosynthesis in a tree plant.

Optimization of Coconut Water Beverage Fermented with Lactobacillus acidophilus

Coconut water is the liquid endosperm of coconut. It is a very nutritious and refreshingly natural beverage but highly perishable. The study aimed to optimize and evaluate the coconut water beverage formulation. A 33 factorial experiment arranged in Central Composite Design with the levels of Lactobacillus acidophilus starter culture (10, 15, 20%), pineapple puree as flavorant (5, 15, 25%) and sugar (10, 20, 30%) as the independent variables was used. The growth pattern of the lactic acid bacteria was monitored for 32 hours following serial dilution and pour plating techniques to determine the fermentation time to produce the beverage. Sensory evaluation was conducted using the 9-point Hedonic scale. Response surface methodology was used to identify the optimum formulation. Microbial growth indicated that 24 hours of incubation at 37°c can produce the fermented beverage. With increased level of Lactobacillus acidophilus starter culture, pineapple puree and sugar, acceptability for the product increased. The optimum formulation has 30% sugar, 20% starter culture and 15% pineapple puree. The product is more nutritious than the unfermented beverage and still acceptable when stored at refrigerated condition for 15 days. Fermentation increased the nutritional values of fresh coconut water.

Comparative resistances of selected spoilage and pathogenic bacteria in ultraviolet-C-treated, turbulent-flowing young coconut liquid endosperm

This study determined and compared the inactivation rates of selected spoilage and pathogenic bacteria in turbulent flowing, UV-C treated liquid endosperm (pH 5.80, 6.10 °Brix) obtained from young (6–9 months) coconut drupes. Inoculation of test organisms significantly altered the UV-C absorbance and transmittance of the liquid endosperm from 0.90 to 1.08 and 12.74%–8.39%, respectively. Inactivation rates were expressed in terms of decimal reduction times (D values), defined as the exposure time necessary to reduce the test organism by 90% or 1-log cycle. Furthermore, the DUV-C values, or the UV-C dose necessary to reduce the organism by 90% were also determined. Results showed that while the D and DUV-C values significantly varied among the spoilage organisms (D = 2.93–5.60 s; DUV-C = 7.63–14.56 mJ/cm2), no significant differences were detected in the inactivation rates of the tested pathogens (D = 3.19–3.76 s; DUV-C = 8.28–9.78 mJ/cm2). The inactivation parameters obtained in this work were close to those previously established in non-turbulent, small volume coconut liquid endosperm, suggesting that for this commodity, stirring may not be necessary to optimize microbial inactivation if UV-C shall be applied to small volumes or thin films. The results established in this work may serve as baseline information in the continuous optimization of UV-C process for coconut liquid endosperm and other similar products, for the maintenance and control of food quality and safety.

Reference organism selection for microwave atmospheric pressure plasma jet treatment of young coconut liquid endosperm

This study identified a reference organism for the establishment of microwave atmospheric pressure plasma jet treatment of young coconut liquid endosperm. Three different, predominant spoilage bacteria were isolated from spoiled liquid endosperm and identified through 16S rDNA sequencing, prior to propagation and eventual challenge studies. Basic Local Alignment Search Tool comparisons revealed that the isolated spoilage bacteria were Klebsiella sp., Staphylococcus sp., and Kluyvera sp (%Identity 97.34–97.82%). The isolates were propagated to mid-stationary growth phase (17 h) and thereafter suspended in liquid endosperm. The inactivation rates of the spoilage isolates in liquid endosperm subjected to plasma jet at 450 and 650 W input power settings were determined and compared to those of pathogens Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes. Inactivation rates of all test organisms at 450 W (2.76–5.98 min) were significantly less (p < 0.05) than those at 650 W (1.86–3.11 min). In both power settings, S. enterica exhibited the significantly (p < 0.05) greatest resistance towards plasma treatment, while Staphylococcus sp. exhibited the least. Heat penetration studies in both power settings revealed that the temperature of the liquid endosperm did not significantly increase and did not reach bactericidal ranges (<30 °C) during plasma jet treatment, hence the observed inactivation were attributed to antimicrobial species generated by the plasma. Optical emission spectroscopy revealed that these antimicrobial species included atomic oxygen (777.41 and 844.67 nm) and ultraviolet radiation (200–280 nm). Thus, this study determined S. enterica as an appropriate target organism for the establishment of plasma jet process for coconut liquid endosperm, the inactivation rate of which shall be soon established in higher scale treatment process.

LEPTIN LEVELS ATTENUATED BY COCONUT WATER IN HIGH‐FAT AND HIGH‐FRUCTOSE DIET FED ANIMAL MODELS

Coconut water is the liquid endosperm of coconut fruitrich in important nutrients such as vitamins, phytohormones, amino acids andphytochemicals. Tender coconut water, the fluid present in young green coconuts and mature coconut water, the clear liquid present in the older brown coconut have been shown to significantly reduce hyperlipidemia in cholesterol fed rats. Leptin is a 16 KDa peptide hormone that is the product of ob gene in adipose tissues. Leptin level in circulation is directly related to adipose tissue mass. The effect of tender and mature coconut water on the leptin level of high‐fat and high‐fructose diet fed rats was investigated in this study. 55 rats were separated into 11 experimental groups of which 4 groups each had high‐fat and high‐fructose feeding respectively with and without coconut water treatment. The rats were fed for 8 weeks followed by 4 weeks of treatment with tender coconut water, mature coconut water and atorvastatin as reference standard. Leptin level was significantly reduced(p&lt;0.01) by tender and mature coconut water in a manner that was comparable to atorvastatin in both high‐fat and high‐fructose diet fed rats. Leptin lowering in the high‐fat fed rats was similar in both mature and tender coconut water, but the lowering effect was more in the mature coconut water (MCW) than in the tender coconut water (TCW) in the high‐fructose fed rats. Tender and mature coconut water thus, have a lowering effect on leptin level in circulation. This lowering effect might be due to the reduction of adipose tissue mass by the metabolic action of tender and mature coconut water or the interplay of their phytochemical and proximate constituents in a synergistic fashion or the contribution of all the factors.Support or Funding Informationna

Antimicrobial peptide (Cn-AMP2) from liquid endosperm of Cocos nucifera forms amyloid-like fibrillar structure.

Cn-AMP2 is an antimicrobial peptide derived from liquid endosperm of coconut (Cocos nucifera). It consists of 11 amino acid residues and predicted to have high propensity for β-sheet formation that disposes this peptide to be amyloidogenic. In the present study, we have examined the amyloidogenic propensities of Cn-AMP2 in silico and then tested the predictions under in vitro conditions. The in silico study revealed that the peptide possesses high amyloidogenic propensity comparable with Aβ. Upon solubilisation and agitation in aqueous buffer, Cn-AMP2 forms visible aggregates that display bathochromic shift in the Congo red absorbance spectra, strong increase in thioflavin T fluorescence and fibrillar morphology under transmission electron microscopy. All these properties are typical of an amyloid fibril derived from various proteins/peptides including Aβ.

Fruit growth and lipid accumulation in the solid endosperm of ta xanh coconut cultivar (Cocos nucifera L.)

This study is conducted to discover the relationship between the growth ta xanh coconut fruit and lipid accumulation in its endosperm. During the fruit development period, several criteria are determined, such as the fresh and dry weight of the crustal or seed, the amount of glucose, protein and lipid in the liquid and solid endosperm. The growth period of ta xanh coconut fruit is 12 months and is divided into four stages, lasting from fruit set to harvest. Each stage lasts about three months: (1) young fruit stage, (2) the growth fruit stage, (3) the growth solid endosperm stage (coconut meat), (4) the maturation and ripening stage. In particular, the young fruit period is the slow growth period of the fruit, followed by the second stage that is marked by a rapid growth of fruit in crustal and liquid endosperm (coconut milk). At the end of this stage, the liquid endosperm not only reaches the maximum size and weight but also contains the highest level of glucose and starch. During the third stage (7th - 9th month), the volume and content (glucose and starch) of the liquid endosperm remain stable. In this stage, the solid endosperm is formed from the liquid endosperm. The final stage is that of reducing the volume of the liquid endosperm whereas the embryo and solid endosperm grow significantly. Additionally, maximum lipid accumulation occurred in both liquid and solid endosperm.

Previous physicochemical stress exposures influence subsequent resistance of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes to ultraviolet-C in coconut liquid endosperm beverage

This study investigated the influences of prior exposures to common physicochemical stresses encountered by microorganisms in food and food processing ecologies such as acidity, desiccation, and their combinations, on their subsequent susceptibility towards UV-C treatment in coconut liquid endosperm beverage. Cocktails of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes were separately subjected to gradually acidifying environment (final pH4.46), exposed to abrupt desiccation by suspension in saturated NaCl solution (aw=0.85) for 4, 8, and 24h, and sequential acidic and desiccated stresses before suspending in the coconut beverage for UV-C challenge. The exposure times (D) and UV-C energy dose values (DUV-C) necessary to reduce 90% of the population of the different test organisms varied with previous exposures to different sublethal stresses, indicating possible influence of implicit microbial factors towards resistance to UV-C. All tested individual and combined stresses resulted in increased resistance, albeit some were not statistically significant. Non-stressed cells had D values of 3.2–3.5s, and corresponding DUV-C values of 8.4–9.1mJ/cm2. Cells exposed to previous acid stress had D values of 4.1–4.8s and corresponding DUV-C values of 10.7–12.5mJ/cm2. Prior exposure to desiccation resulted in D values of 5.6–7.9s and DUV-C values of 14.7–20.6mJ/cm2, while exposure to combined acid and desiccation stresses resulted in D values of 6.1–8.1s and DUV-C values of 15.9–21.0mJ/cm2. The D and DUV-C values of S. enterica after previous exposure to sequential acid (24h) and desiccation (24h) stresses were found significantly greatest, making the organism and physiological state an appropriate reference organism for the establishment of UV-C pasteurization process for the beverage.

Assessment of volatile and non-volatile organic compounds in the liquid endosperm of young ‘Nam Hom’ coconut (Cocos nucifera L.) at two stages of maturity

SUMMARYYoung coconut (Cocos nucifera L.) fruit collected 6–8 months after anthesis (MAA) contain a high volume of water [20% (w/w)] and can provide a refreshing drink. The present study investigated volatile organic compounds (VOCs), as aroma components, and physico-chemical changes in the liquid endosperm of young ‘Nam Hom’ coconut at two stages of maturity: the one-layer stage (6 MAA) and the two-layer stage (7.0–7.5 MAA) of the flesh. The liquid endosperm of coconut fruit becomes sweeter and more turbid late during maturation. Lauric acid (C12:0) and myristic acid (C14:0) were the main free fatty acids in the liquid endosperm of coconut. Short-chain fatty acid (C10–C12) concentrations increased slightly, and longer-chain fatty acid (C14–C18) concentrations declined when fruit matured from the one- to the two-layer stage of flesh. Solvent extractions showed a 1.4-fold increase in the total concentration of VOCs in the liquid endosperm during fruit development. This was related to a major increase in squalene and sterols, to 21.7% (w/w) of the total VOC and non-volatile organic compounds, whereas the concentrations of terpenes and esters remained stable. Although a series of alkanes existed in the liquid endosperm of coconut, the main aroma components were 2-methyl-1-butyl acetate and terpenes such as D-limonene, α-pinene, and 3-carene. We conclude that, when coconut fruit developed from the one- to the two-layered flesh stage, the liquid endosperm not only became sweeter and contained higher concentrations of aroma volatile and non-volatile components, but also became oily and less translucent.

Application of ultraviolet-C radiation to inactivate acid-and-desiccation stressed Salmonella enterica in young and mature coconut liquid endosperm mix beverage

The occurrences of outbreaks of infections due to consumption of unpasteurized fruit beverages, and the negative effects of heat treatment towards quality are features of the consumer demand paradox on safety and quality that the industry has to address. This study established the efficacy of ultraviolet-C (UV-C) treatment against acid-and-desiccation stressed Salmonella enterica; and applied and evaluated a process schedule with a recommended lethal rate of 99.999% against the target pathogen. Determinations of decimal reduction times revealed that suspension volume and flow property significantly affected inactivation of the test organism, which exhibited the greatest resistance to UV-C when suspended in 500 ml, non-agitated coconut beverage. A UV-C process schedule with a level of lethality of 5-log cycle reduction against the reference organism was then applied to the beverage. Quality evaluations showed that the pasteurization process resulted in significant color changes in the beverage. The process also significantly affected the microbiology of the beverage, but the population of spoilage microorganisms continuously increased during storage; surpassing microbial limits by the 2nd d of refrigerated storage. The sensory quality scores of the processed beverage were not significantly different from the non-processed control, and were higher than an established commercial brand.

Influences of malic acid and nisin supplementations on the decimal reduction times of Escherichia coli O157:H7 in mildly-heated young coconut liquid endosperm

This study was conducted to determine the effects of malic acid (800–1500 ppm) and nisin (0–150 ppm) on the heat resistance of Escherichia coli O157:H7 in young coconut liquid endosperm. The Central Composite Rotatable Design was applied to determine the various combinations of the two supplements to be added to young coconut liquid endosperm. The lowest D55 value was observed in the combination of 1500 ppm malic acid and 75 ppm nisin at 14.89 ± 4.17 min, while highest was 27.04 ± 4.98 min in the combination of 1150 ppm malic acid and 75 ppm nisin. The D55 values established from the combinations tested did not significantly vary, indicating that within the ranges of supplementation tested, significant influences of both additives and their interaction on the heat resistance of the pathogen did not exist. It was however emphasized that all supplementation combinations resulted in D55 values significantly lower than that in the unsupplemented medium, reducing the heat resistance of the cells by as much as 3-folds. Therefore, thermal processes to be established in the supplemented liquid endosperm shall be less severe, and may be applied to preserve sensory attributes.

Evaluation of sodium benzoate and licorice (Glycyrrhiza glabra ) root extract as heat-sensitizing additives against Escherichia coli O157:H7 in mildly heated young coconut liquid endosperm

This study evaluated the use of sodium benzoate (SB) and licorice root extract (LRE) as heat-sensitizing additives against Escherichia coli O157:H7 in mildly heated young coconut liquid endosperm. Consumer acceptance scoring showed that maximum permissible supplementation (MPS) levels for SB and LRE were at 300 and 250ppm, respectively. The MPS values were considered in the generation of a 2-factor rotatable central composite design for the tested SB and LRE concentration combinations. Liquid endosperm with various SB and LRE supplementation combinations was inoculated with E.coli O157:H7 and heated to 55°C. The susceptibility of the cells towards heating was expressed in terms of the decimal reduction time (D55 ). Response surface analysis showed that only the individual linear effect of benzoate significantly influenced D55 value, where increasing supplementation level resulted in increasing susceptibility. The results reported could serve as baseline information in further investigating other additives that could be used as heat-sensitizing agents against pathogens in heat-labile food systems. Fruit juice products have been linked to outbreaks of microbial infection, where unpasteurized products were proven vectors of diseases. Processors often opt not to apply heat process to juice products as the preservation technique often compromises the sensorial quality. This work evaluated two common additives for their heat-sensitizing effects against E.coli O157:H7 in coconut liquid endosperm, the results of which may serve as baseline information to small- and medium-scale processors, and researchers in the establishment of mild heat process schedule for the test commodity and other similar products.