Enzyme assisted juice extraction from Dacryodes macrophylla as a potential bio-resource for wine production.

Atom fruit (Dacryodes macrophylla) is a Non-timber Forest Product (NTFP) that comprises a large seed, thick pulp, and a thin hard outer covering. The structural component of its cell wall and thick pulp make it difficult in extracting the juice. Also, Dacryodes macrophylla fruit is greatly underutilized, therefore the need to process and transform it into other value-added products. This work aims to enzymatically extract juice from Dacryodes macrophylla fruit with the aid of pectinase, ferment and test the acceptability of wine produced from this extract. The enzyme and non-enzyme treatments were carried out under the same conditions and their physicochemical properties such as pH, juice yield, total soluble solids, and Vitamin C were compared. A central composite design was used for the optimization of the processing factors for the enzyme extraction process. Enzyme treatment had a great impact on the juice yield (%) and Total soluble solids (TSS) (0Brix) of samples as it was as high as 81 ± 0.7% and 10.6 ± 0.02 0Brix whereas, that of the non-enzyme treatments were 46 ± 0.7% and 9.5 ± 0.02 0Brix respectively. However, the Vitamin C content of enzyme-treated juice decreased to 11.32 ± 0.13 mg/ml as compared to that of the non-enzyme-treated juice sample (15.7 ± 0.04 mg/ml). The optimum processing condition in the extraction of juice from the atom fruit was 1.84% enzyme concentration, 49.02 Ö¯C Incubation temperature, and 43.58 min Incubation time. During wine processing within 14 days of primary fermentation, the pH of the must decreased from 3.42 ± 0.07 to 3.26 ± 0.07 whereas the Titratable acidity (TA) increased from 0.16 ± 0.05 to 0.51 ± 0.0. The wine produced from Dacryodes macrophylla fruit showed promising results as its sensorial scores for all attributes including color, clarity, flavor, mouthfeel, alcoholic burn after taste and overall acceptability were all above 5. Thus, enzymes can be used to improve the juice yield of Dacryodes macrophylla fruit and hence, can be a potential bioresource for wine production.

Synergistic interactions in dilute aqueous solutions between alginate and tropical vegetal hydrocolloids.

Encapsulation in alginate beads has always been limited by the leakage due to the too wide distribution of pore sizes. Mixing alginate with other polymers have sometimes reduced the problem. Hydrocolloids from seven tropical vegetal species (barks of Triumfetta cordifolia and Bridelia thermifolia, seeds of Irvingia gabonensis and Beilschmiedia obscura, and leaves of Ceratotheca sesamoides, Adansonia digitata and Corchorus olitorius) were screened for synergistic interactions with alginate in dilute aqueous solution. Mixtures with alginate were made at different volume proportions and deviations from the initial viscosity set at 1 were evaluated. In distilled water, the gums from T. cordifolia, B. obscura, C. sesamoides and C. olitorius presented synergies with alginate. In 2 mM calcium chloride, the seven gums showed positive synergy. Interactions are favored by gum flexibility and the presence of charges, although high charges reduced the interactions. Alginate fraction of maximum viscosity enhancement depends on the ability to conformational order of the gum. The measure by laser diffraction of alginate-gum particles sizes at different fractions showed that the cooperative interactions did not always involve the largest complexes formed in gums associations. The occurrence of these interactions predicts the formation of homogeneous mixed gels at higher polymer and calcium concentrations.

Antioxidant activities of essential oil of Bidens pilosa (Linn. Var. Radita) used for the preservation of food qualities in North Cameroon.

This study aimed to determine the total antioxidant capacity of the essential oil (EO) of leaves of Bidens pilosa (Linn. Var. Radita) used as protectant of stored grains in Northern Cameroon. EO was characterized by GC-FID, antioxidant activity (AA) was determined by combining: evaluation of radical-scavenging activity, reducing power (RP) and co-oxidation of ß-carotene methods. Tests were carried out on crude and stored EO kept for two weeks at 31.48 ± 2.88°C and 58.56 ± 6.78% relative humidity. These conditions are the same as those of grain storage. GC analyses enabled the identification of 27 compounds, representing around 97.57% of the total oil contents. The major constituents of the EO were α-pinene (14.7%), ε-caryophyllene (13.5), and ß-ocimene (12.8%). The AA of the crude and stored EO are proportional to the concentrations and time of exposition. Exposed at the day light, this EO inhibit 77.4-18.69% for the DPPH system, 59.55-19.14% for RP method and 91.88-21.8% for ß-carotene-linoleate model system, respectively, from crude and 15 days storage EO at 20 mg L(-1). For the EC50 values, ß-carotene method is excellent and in the decreasing order of DPPH method, PR with 2.52 mg L(-1), 2.77 mg L(-1) and 4.13 mg L(-1), respectively, for the crude oil. The ET50 were 1.59 days for the RP method and 2.88 days DPPH system and ß-carotene-linoleate model system at 20 mg L(-1). These results showed that the EO of B. pilosa leaves exhibits AA that might be an added value for this EO preventing stored products from pest attacks.

Identification of soil bacteria able to degrade phenanthrene bound to a hydrophobic sorbent in situ.

Efficient bioremediation of PAH-contaminated sites is limited by the hydrophobic character and poor bioavailability of pollutants. In this study, stable isotope probing (SIP) was implemented to track bacteria that can degrade PAHs adsorbed on hydrophobic sorbents. Temperate and tropical soils were incubated with (13)C-labeled phenanthrene, supplied by spiking or coated onto membranes. Phenanthrene mineralization was faster in microcosms with PAH-coated membranes than in microcosms containing spiked soil. Upon incubation with temperate soil, phenanthrene degraders found in the biofilms that formed on coated membranes were mainly identified as Sphingomonadaceae and Actinobacteria. In the tropical soil, uncultured Rhodocyclaceae dominated degraders bound to membranes. Accordingly, ring-hydroxylating dioxygenase sequences recovered from this soil matched PAH-specific dioxygenase genes recently found in Rhodocyclaceae. Hence, our SIP approach allowed the detection of novel degraders, mostly uncultured, which differ from those detected after soil spiking, but might play a key role in the bioremediation of PAH-polluted soils.

Aroma compound analysis of Piper nigrum and Piper guineense essential oils from Cameroon using solid-phase microextraction-gas chromatography, solid-phase microextraction-gas chromatography-mass spectrometry and olfactometry.

The investigation of aroma compounds of the essential oils of dried fruits of black pepper (Piper nigrum) and black and white "Ashanti pepper" (Piper guineense) from Cameroon by means of solid-phase microextraction (SPME) was carried out for the first time to identify the odorous target components responsible for the characteristic odor of these valuable spices and food flavoring products. By means of GC-flame ionization detection (FID) and GC-MS (using different polar columns) the main compounds (concentration >3.0%, calculated as area of GC-FID analysis using a non-polar fused-silica open tubular RSL-200 column) of the SPME headspace samples of P. nigrum (black) and P. guineense (black and white) were found to be: P. nigrum (black)--germacrene D (11.01%), limonene (10.26%), beta-pinene (10.02%), alpha-phellandrene (8.56%), beta-caryophyllene (7.29%), alpha-pinene (6.40%) and cis-beta-ocimene (3.19%); P. guineense (black)--beta-caryophyllene (57.59%), beta-elemene (5.10%), bicyclogermacrene (5.05%) and alpha-humulene (4.86%); and P. guineense (white)--beta-caryophyllene (51.75%), cis-beta-ocimene (6.61%), limonene (5.88%), beta-pinene (4.56%), linalool (3.97%) and alpha-humulene (3.29%). The most intense odor impressions of the essential oils of the various dried pepper fruits were given byprofessional perfumers as follows: P nigrum (black)--fine, pleasant black pepper note; P. guineense (black)--black pepper top-note; and P. guineense (white)--pleasant white pepper note. These analytical results for the SPME headspace samples of three different pepper species from Cameroon are in accordance with the olfactoric data of the corresponding essential oils. A GC-sniffing technique was used to correlate the single odor impression of the identified SPME headspace volatiles of the three investigated pepper samples with the following results: themain compounds such as beta-caryophyllene, germacrene D, limonene, beta-pinene, alpha-phellandrene and alpha-humulene, as well as minor constituents such as delta-carene, beta-phellandrene, isoborneol, alpha-guaiene, sarisan, elemicin, calamenene, caryophyllene alcohol, isoelemicin, T-muurolol, cubenol and bulnesol, are of greatest importance for the characteristic pepper odor notes of these three Piper samples. Further aroma impressions can be attributed to mono- and sesquiterpenes, hexane, octane and nonane derivatives.