15 research outputs found
Respiração e produção de etileno em beterrabas inteiras e minimamente processadas submetidas a tratamentos com etileno e biorreguladores
Effect of 1-methylcyclopropene on the quality of minimally processed pineapple fruit
Rapid deterioration is a problem with minimally processed pineapple fruit. Effects of 1-methylcyclopropene treatment with or without ascorbic acid treatment on respiration rate, browning and other quality parameters were investigated for minimally processed fruit stored at 4.5degreesC for 12 days in air. 1-methylcyclopropene treatment reduced respiration rate and browning, and maintained more acceptable visual quality in pineapple fruit slices. 1-methylcyclopropene-treated pineapple fruit slices reached an unacceptable visual quality level after day 8. In contrast, untreated slices were unacceptable after 4 days storage. Respiration rate was reduced from about 5.8 mL CO2/kg.h in control fruit to about 4.8-5.0 mL CO2/kg.h in 1-methylcyclopropene- treated fruit at 12 days. Lightness of control pineapple slices reduced from L* 77 to 65 over 12 days, while 1-methylcyclopropene- treated fruits remained at about L* 72. 1-methylcyclopropene treatment increased electrolyte leakage from pineapple slices. Apart from further suppression of respiration rate, there was no benefit of using 1-methylcyclopropene at above 1.0 muL/L. 1-methylcyclopropene treatment reduced ascorbic acid loss from 44% for untreated fruit to 29% for 1-methylcyclopropene- treated fruit at the end of the 12-day storage. An additive effect of 1-methylcyclopropene treatment was recorded for pineapple fruit slices dipped in 2% (w/v) ascorbic acid solution for 3 min. Ascorbic acid treatment resulted in reduced browning, electrolyte leakage and fruit softening. Therefore, 1-methylcyclopropene treatment helps maintain the quality of minimally processed pineapple fruit at least partially by reducing the hydrolysis of endogenous ascorbic acid
Effect of modified atmosphere packaging on the quality of minimally processed pineapple cv.'Smooth Cayenne' fruit
The effects of modified atmosphere (MA) conditions on the quality of minimally processed pineapple slices were determined. Commercial pineapple slice packs sealed with 40 pm thick polyester film were kept at 4.5 degrees C for 14 d. The oxygen transmission rate of the film was 23 ml m(-2) day(-1) atm(-1) (at 25 degrees C, 75% RH). In-built atmospheres and the quality of the products were determined. O-2 concentrations within the packs stabilised at 2%, while CO2 concentrations increased to 70% by day 14. The high CO2 level suggested an inappropriate lidding film permeability for the product, and hence affected its quality. Three batches of pineapple slices were packed in the laboratory using lidding films with oxygen transmission rate of 75, 2790 or 5000 ml m(-2) day(-1) atm(-1) (at 23 degrees C, 0% RH). Headspace atmospheres from laboratory-packed pineapple slices suggested an optimum equilibrium modified atmosphere of ca. 2% O-2 and 15% CO2. Respiration data from the laboratory-prepared packs were pooled together and used to develop a correlation model relating respiration rates to O-2 and CO2 concentrations. The model showed a decrease in respiration rate with decreasing O-2 and increasing CO2 concentrations. Respiration rate stabilised at 2% 02 and 10% CO2. The high concentrations of CO2 observed in the commercial packs did not fit the range in the respiration model. The model could aid in selection of MA conditions for minimally processed pineapple fruit
Variability In Biochemical Composition And Cell Wall Constituents Among Seven Varieties In Ghanaian Yam ( Dioscorea Sp.) Germplasm
This work characterized the most cultivated and consumed yam (
Dioscorea ) cultivars within the Ghanaian yam germplasm based on their
biochemical and cell wall constituents to assess their potential
alternative food and industrial processing applications. Samples were
analyzed for their biochemical composition - starch, amylose,
amylopectin, total sugars, reducing sugars and non-reducing sugars
along the head, middle and tail regions of each tuber using standard
analytical methods. Cell wall constituents - acid detergent fibre,
neutral detergent fibre, acid detergent lignin, cellulose and
hemicellulose of each tuber were also determined using standard
analytical methods. The results showed no significant differences at
p<0.05 in biochemical compositions along the length of the studied
cultivars. D. cayenensis (Pure-yellow), D. rotundata (Pona) and D.
alata (Matches) were found to have high starch contents
(63.16-65.69%, 63.54-65.30% and 63.24-65.17% respectively). Amylose
content was observed to vary along the length of the tubers for the
varieties studied. D. alata (Matches) was observed to contain the
highest amylose content of 19.66-20.64%. No identifiable trend was
however, observed for the amylopectin content along the length between
the varieties investigated. D. bulbifera recorded the lowest
amylopectin content of 41.29%, 43.59% and 44.63% while D. esculenta
had the highest with 49.84%, 50.24% and 50.13% along the tail, middle
and head sections respectively. Total sugar content varied
significantly (p<0.05) along the lengths of all the varieties
investigated. It was higher at the tail portions for all the varieties
studied than the head regions; the middle portions recorded the least.
D. bulbifera recorded highest total sugar contents (4.74-4.84%) and
total sucrose (3.58-3.64%). There were significant differences
(p<0.05) in the cell wall constituents of the yam varieties.
Cellulose was found to be the most common cell wall component with D.
rotundata having the highest level of 3.36% whilst D. dumetorum had
the least (1.56%). Hemicellulose content ranged between 0.42 g/100g in
D. alata to 4.58 g/100g in D. esculenta whiles lignin content ranged
from 1.56 g/100g in D. dumetorum to 2.87 g/100g for D. praehensalis
There were significant differences (p<0.05) in the neutral detergent
fibre found in Dioscorea esculenta and the other yam species. It ranged
from 1.18 g/100g in D. alata to 5.46 g/100g in D. esculenta. Less than
1% of acid detergent fibre was identified in the yam varieties,
suggesting varied levels of biochemical composition and cell wall
constituents in the different yam varieties. Key words: Biochemical
quality, cell wall composition, yam