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

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

Variability in biochemical composition and cell wall constituents among seven varieties in Ghanaian yan (Dioscorea SP) germplasm

This work characterized the most cultivated and consumed yam ( Dioscorea ) cultivars within the Ghanaian yam germpla sm 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 sugar s 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&lt;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 con tent 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&lt;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&lt;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 while lignin content ranged from 1.56 g/100g in D. dumetorum to 2.87 g/100g for D. praehensalis . There were significant differences (p&lt;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 .</jats:p

Roasting effects on phenolic content and free-radical scavenging activities of pulp preconditioned and fermented cocoa (Theobroma cacao) beans

Polyphenols are phytochemicals responsible for the astringency, bitterness, green flavours and antioxidant activities in Theobroma cacao beans. Polyphenols degradation in cocoa beans during roasting is crucial to the flavour outcome and it is influenced by factors such as temperature, time and pod storage. Antioxidants are compounds that help to inhibit oxidation reactions caused by free radicals such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite thereby preventing damage to the cells and tissues. Their mechanisms of action include scavenging reactive oxygen and decreasing localised oxygen concentration thereby reducing molecular oxygen’s oxidation potential, metabolising lipid peroxides to n on-radical products and chelating metal ions to prevent generation of free radicals in humans. The study aimed at investigating changes in total polyphenols, anthocyanins, o -diphenols and antioxidant activity (free-radical scavenging activities) after roasting of pulp pre- conditioned and fermented cocoa beans using standard analytical methods. A 4×4 full factorial design with the principal experimental factors as pod storage time (0, 3, 7 and 10 days) and roasting duration (0, 15, 30 and 45 minutes) at 12 0 o C were used to study the changes in the total polyphenols, anthocyanins, o -diphenols and % free-radical scavenging activities of the cocoa beans. Variable decrease in total polyphenols, o - diphenols and anthocyanins were observed with increase in pre-conditioning (pod storage time) and roasting duration. However, variable trends w ere observed for the % free-radical scavenging activities. The total polyphenols, anthocyanins and o -diphenols in the cocoa beans after 45 minutes roasting decreased in the range 132.24 to 57.17 mg/g, 6.71 to 1.07 mg/kg and 15.94 to 8.25 mg/g respectively at all pod storage treatments. The total polyphenols of the fermented, dried and unstored (freshly harvested) cocoa beans was 132.25 mg/g which reduced to 122.14 mg/g (7.6% degradation), 116.721 mg/g (11.7% degradation) and 92.22 mg/g ( 30.3% degradation) after storage for 3, 7 and 10 days, respectively. The optimum decrease in the % free- radical scavenging activity was 7 days and above of pods storage. Increasing roasting time caused a continuous decrease in the % free-radical scavenging activity from 89.10% to 74.31% after 45 minutes for beans from the unstored ( freshly harvested) pods. However, pod storage caused an increase in the % free radical scavenging activities during roasting. Pulp pre-conditioning (pod storage) and roasting duration could be used to reduce the astringency and bitterness caused b y polyphenols, o - diphenols and anthocyanins in cocoa beans as well as increase t he antioxidant activity imparted by cocoa.</jats:p

Changes in some biochemical qualities during drying of pulp pre-conditioned and fermented cocoa (Theobroma cacao) beans.

Fermentation and drying are critical to the development of flavour precursors that generate into distinctive chocolate flavour notes during industrial manufacture. These processes also lead to reduction in acidity and free fatty acids of nibs, which dictates the levels of bitterness and colour development in chocolates. This study investigated changes in nib acidity, flavour precursors (sugars concentration and proteins) and free fatty acids during drying of pulp pre-conditioned and fermented cocoa beans using a 4 x 3 full factorial experimental design with pod storage (0, 3, 7 and 10 days) and drying time (0, 3 and 6 days) as the principal factors. Non-volatile (titratable) acidity, pH, sugars (reducing, non-reducing and total sugars), changes in protein content and free fatty acids of the beans were studied using standard analytical methods. Increasing pod storage consistently increased pH of the fermented nibs at the end of drying with consequential decrease in titratable acidity. The pH increased from 4.92 for the freshly harvested pods to 6.00 for pods stored for 10 days at the end of the drying process. Similarly, pH of the fermented beans increased with increasing drying time for all pod storage treatment except for pods stored for 10 days. The pH of fermented beans whose pods were stored for 3 and 7 days were 5.26 and 5.56 respectively after drying for 7 days. Protein, reducing sugars, non-reducing sugars and total sugars decreased significantly (p&lt;0.05) with increasing duration of drying at all pod storage periods. Pod storage and drying significantly (p&lt;0.05) increased the free fatty acids content of the fermented nibs. The FFAs of the dried beans increased from 0.47% for the unstored (freshly harvested) pods to 0.55% for pods stored for 3 and 7 days and 0.58% for pods stored for 10 days. However, FFAs content of all the dried fermented beans were below the acceptable limits of 1.75% oleic acid equivalent in cocoa butter at all pod storage periods. Storage of cocoa pod between 3–7 days with 7 days of drying (after 6 days fermentation) led to considerable reductions in nib acidity, reducing sugars, nonreducing, total sugars and proteins and acceptable FFA levels.</jats:p