Potato, methanolic extracts

Figure 11.12. DTA curves of potato and corn starch, (a) Potato starch (b) potato starch, duplicate run (c) corn starch (d) methanol-extracted corn starch (c) ammonia-prcgelatinizcd corn starch...

Figure 4. Matrix effects in ELISA of aqueous and methanolic extracts of potato and tobacco using purified anti-maleic hydrazide monoclonal antibodies (modified from ref. 15).

H-NMR spectra of methanolic extracts of control and genetically modified varietals of tomatoes have been analyzed using chemometric techniques. It was possible to assess variations in several metabolites. H, H, and solid-state magic angle spinning (MAS) NMR spectra have been recorded for tomato skin and potato tissue, providing information on the structure and dynamics of the cuticle polyesters. 

A homogenized sample of cereals, vegetables, fruits or potatoes (10-20 g) is extracted with an organic solvent such as acetone and methanol. After filtration, the extract is concentrated to about 20 mL by rotary evaporation below 40 °C. The residue is transferred with 5% sodium chloride (NaCl) aqueous solution and partitioned twice with n-hexane. The n-hexane extracts are dried with anhydrous sodium sulfate and subjected to a Florisil column chromatographic cleanup procedure. The eluate from the Horisil column is concentrated to dryness and the residue is dissolved in an appropriate amount of acetone for analysis by GC/NPD. ... 

Lipids can be identified and quantified using thin-layer chromatography (TEC) and gas chromatography (GC) (Galliard, 1968). Extraction of lipids is achieved by homogenizing potato tubers with isopropanol in a blender, followed by a series of filtrations and extractions with chloroform-methanol (2 1). Chloroform is removed by rotary evaporation and the residue is redissolved in benzene-ethanol (4 1). This extract is passed through a DEAE-cellulose column, and the fractions collected are subjected to TEC on 250 p,m layers of silica gel G, using three solvent systems. Fatty acid methyl esters for GC analysis are prepared by transmethylation of the parent lipids, or by diazomethane treatment of the free fatty acids released by acid... 

SFE determinations of fat in potato chips and cheese curls were virtually identical to the values obtained by Soxhlet extraction, while the results from SFE of com chips was a few percent low. The low results can be attributed to the SFE of the com chips being performed without adding methanol to the sample cartridge and also to the fact that SOml less CO2 was used in the extraction. 

Likewise, furfural (peak 16, 8.1 minutes) was observed in both microwave and conventionally baked cake, but at a significantly higher level in the latter. Methyl pyrazine (peak 15, 7.8 minutes), furan methanol (peak 17, 9.0 minutes), and acetyl furan (peak 22, 10.9 minutes), were present in the conventional cake samples as were two unidentified compounds (peaks 3 and 9, 3.3 and 5.0 minutes) observed to have buttery, caramel-like aromas. Several other minor peaks were also observed only in the conventional cake. It should be noted that a few nutty, brown, and potato type smells were detected in areas of the conventional cake chromatogram where no peaks were integrated. These aromas suggest the presence of other Maillard compounds in the extract at levels too low for instrumental detection. 

Figure 7. Potato and rice extracts comparison of fluorescence and absorbance detection modes after HPLC on a CN-bonded polar phase (0.2 ppm = 100 ng carbaryl/500 mg crop equivalent injected mobile phase methylene chloride/methanol 99.5/0.5)...

The amino-type stationary phase was also used in more recent studies by Bushway 9 10. For the separation of a-chaconine and a-solanine in potato extracts, the mobile phase tetrahydro-furan - acetonitrile - water - methanol (50 25 15.5 9.5) was used, resulting in a considerably reduced analysis time when compared to the previously reported methods. For analysis of the alkaloids and their metabolites, the mobile phase ratio was changed to (55 30 10 5)(Fig.10.7). For separation of the lower glycosides from a-chaconine and a-solanine, a carbohydrate analysis column was used in combination with the mobile phase tetrahydrofuran - water - acetonitrile (55 8 37)(Fig.l0.8)10. 

Leafedisk Antifeedant Bioassay Ten l.O cm sweet potato leaf disks were placed in marked wells in an agar-coated petri dish. Five disks were alternatively treated with 10 pi of plant extract (100 pg/cm ) or solvent (acetone or methanol). Five third instar Spodoptera litura (Lepidoptera Noctuidae) larvae per dish and three dishes were used per treatment. The treated dishes were placed in an incubator at 27 C and 75-80% RH for 16-18 hours in darkness. The leaf surface consumed was measured with a video camera interfaced to a personal computer as described earlier (6). The feeding index was calculated as 1= %T / (%T + %C) (%T = % of treated disks consumed, %C = % of control disks consumed). An arbitrary level of I<20 was used as the criteria to determine effective feeding deterrents (7). 

NiP-CPE DPV Potato flakes Liquid-liquid extraction using methanol/water (50% v/v) followed by pre-concentration in a vacuum rotary evaporator. BHA Ruiz et al. (1994)... 

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