We have established that `d'Anjou' pears (Pyrus communis) are properly ripened for fresh-cut use when flesh firmness (FF) is between 5 lb (2.3 kg) and 7 lb (3.2 kg). In this study, the fruit was ripened in air enriched with 100 ppm (mL·L-1) ethylene at 68 °F (20.0 °C). Afterward, we investigated three slicing methods, each employing a fruit sectionizer for dividing individual pears into eight wedges. The easiest and most convenient cutting procedure involved pouring an antibrowning agent onto the incision, but without allowing the fruit to directly contact the air. We evaluated various combinations of L-ascorbic acid (vitamin C) and potassium chloride (KCl) for their ability to prevent any discoloration while also not affecting taste or injuring the cut surface. The most suitable antibrowning solution contained 10% L-ascorbic acid and 2% KCl (pH 2.3). A dipping time of 30 s was sufficient for maintaining the wedges with little discoloration over a 14-d period, at either 30 or 35 °F (-1.1 or 1.7 °C). Here, we also present a prototype design for a 1.6-pt (0.76-L) transparent plastic container with eight compartments for holding wedges sliced with a commercially available sectionizer.
A comparison of sanitizers for fresh-cut mango (Mangifera indica cv. Keitt) was made. Mangos were obtained from a farm in Homestead, Fla., and stored at 15 °C until processed. Before cutting, fruit were dipped in solutions of either sodium hypochlorite (NaOCl) (200 ppm) or peroxyacetic acid (100 ppm). The cut pieces were dipped in acidified sodium chlorite (NaClO2) (200 ppm, pH 2.6) or dilute peroxyacetic acid (50 ppm) for 30 seconds. Resulting cut slices were placed in polystyrene clamshell food containers and stored at 5 °C for 21 days. Samples in the clamshells were tested for changes in microbial stability and for quality parameters every 7 days. Results showed that even though the fruit slices were sanitized after cutting, cut fruit microbial populations were related to the method of whole fruit sanitation. After 15-21 days in storage at 5 °C, cut slices from whole fruit sanitized with peroxyacetic acid that were subsequently treated with dilute peroxyacetic acid or acidified NaClO2 had less contamination [<1 colony-forming unit (cfu) per gram] than samples cut from whole fruit sanitized with NaOCl (<1000 to 3700 cfu/g). These data demonstrate that the method of whole fruit sanitation plays a role in determining the cleanliness of the cut fruit. These sanitizer systems (peroxyacetic acid on whole fruit followed by peroxyacetic acid or acidified NaClO2 on cut slices) effectively reduced microbial growth and kept microbial counts low on cut fruit surfaces for 21 days when compared to cut fruit slices from NaOCl-treated whole fruit.
)] in tap water (pH 2.8, EC 0.49 dS·m −1 ); 3) 10 g·L −1 a propriety mixture of sugar, acidifier and a biocide [FLO (Floralife ® Crystal Clear packets; Floralife, Walterboro, SC)] in tap water (pH 3.1, EC 0.50 dS·m −1 ); 4) deionized water (pH 3.8, EC
models, Eqs. [3] through [7] , were obtained by fixing three factors as the zero levels, whereas the other three factors were set as an explanatory variable (as shown in Figs. 2 and 3 ): y PH = 2 . 696 + 0.295 w + 0 . 216 w 2 [3] y CD = 8 . 414 + 0
. Fig. 1. Relationship between substrate pH and chlorophyll meter readings (SPAD-502; Minolta, Ramsey, NJ) or shoot dry weight (SDW) of ‘Pacifica Blush’ annual vinca grown in switchgrass substrates; SPAD = −2.29 × pH 2 + 29.10 × pH − 38.09, R 2 = 0
) at pH 2.4 ± 0.01 was used for vitamin C analysis. Two milliliters of juice were mixed with 2 mL of 2.4% (w/v) metaphosphoric acid and centrifuged at 6900 g n for 5 min at 5 °C. An aliquot of the centrifuged sample (0.5 mL) was then transferred to a
cool to room temperature, and the solution was filtered through wet filter paper and collected in a 50-mL volumetric flask. The residue was mixed with 20 mL of citrate buffer (pH 2.2) and the amino acid profile was determined using an automatic amino
, which can have secondary effects on potassium (K) uptake in plants. The objectives of this review are to 1) describe the impact of DL rate on substrate pH, 2) discuss the primary and secondary effects of DL on nutrient availability, and 3) summarize the
ethylenediaminetetraacetic acid, pH 2.0); 5-min reaction time] ( Mehlich, 1984 ). At the end of extractions, the supernatant was filtered before being analyzed by the ICP (USEPA method 200.7). The plant samples were dried at 65 °C for 72 h and ground in a Wiley Mill to pass
maintained at 30 °C using a thermostat column compartment. All separations were achieved using gradient mobile phase of 1) reverse osmosis water adjusted to pH 2.5 with trifluoroacetic acid and 2) acetonitrile. The gradient held the following percentages: 15