Giorgia Liguori

Evaluation of fruit quality and antioxidant activity of kiwifruit during ripening and after storage

BACKGROUND: In the Northern hemisphere kiwifruit harvest time is conditioned by low temperatures occurring during the harvesting season while in Southern Italy minimum temperatures in autumn are high enough to support fruit growth and ripening. To evaluate the influence of delayed harvest time on kiwifruit quality attributes. METHODS: The experiment was carried out in a commercial kiwifruit, ‘Hayward’, orchard located in Southern Italy. In this area, the conventional harvest time occurs 160 days after full bloom (DAFB), during the first decade of November. Fruits were collected from 130 DAFB to 192 DAFB. Fresh fruit and dry weight, flesh color, firmness, total soluble solids content (TSS), titratable acidity (TA), ascorbic acid (AA), total polyphenols content (TPH) and antioxidant capacity (TAC) were determined. After 120 days of storage, fruit harvested 178 DAFB, had higher fresh and dry weight, flesh firmness, TSS, TA and lower water loss than fruit harvested at 160 DAFB, with no significant differences in AA, TPH and TAC. TAC was correlated more to TPH than to AA. Early (130–158 DAFB) harvests, resulted in poor fruit quality and scarce post harvest maintenance. Delaying fruit harvest time, in mild winter areas such as Southern Italy, resulted in an improved fruit

Fruit productivity and carbon gain of Opuntia ficus-indica (L.) Mill. trees

Opuntia ficus-indica (OFI) tree and orchards efficiency has been poorly studied, in terms of relation between orchard lay out, light interception, and cropping efficiency. Apparently, there is no other way to increase orchard production than increasing the number either of trees ha-1 or fertile shoots tree-1, considering that a fruit count higher than 6-7 cladode-1 reduces fruit harvest size. The first option requires a reduction of unit tree size and canopy volume. The second option implies the use of large trees that often reduce their efficiency 12-15 years after planting. In 15-year-old OFI trees spaced 6 5 m apart trained to a globe and 2.5-3.0 m high, stem area index (SAI) calculated on the ground surface area covered by the tree was 2.9 and 6.5, respectively, for most active 1- and 2-year-old cladodes and whole canopy surface area. SAI orchard (cladode surface area/ground surface area allotted to the tree) values were slightly lower: 1.8 and 3.9. The proportion of annual dry matter allocated to the...

Effects of rapid refrigeration and modified atmosphere packaging on litchi (Litchi chinensis Sonn.) fruit quality traits

Litchi (Litchi chinensis Sonn.) is a tropical fruit characterized by a rapid pericarp browning and dehydration during postharvest, resulting in an accelerated shelf life and in a loss of consumer appreciation and consequently of its market value. The aim of our study was to assess litchi fruit chemical-physical and sensory quality changes during postharvest and shelf life using rapid refrigeration (RR) and active modified atmosphere packaging (MAP). Litchi fruits were picked at commercial harvest and were divided in 4 groups: not treated fruit (CTR); rapid refrigerated fruit (RRF); modified atmosphere packed fruit (MAP); hydrogen peroxide treated and modified atmosphere packed fruit (MAP+). CTR and RRF fruit were packed in microperforated plastic bag whereas MAP and MAP+ fruit were packed in unperforated high-density polyethylene package in which a gas mixture (60 kPa N2, 30% CO2 and 10 kPa O2) was flushed and then the bag was hermetically sealed. RRF, fruit were submitted to cooling in order to rapidly reduce their temperature using a blast cabinet which allows to reach 4° C in 15 minutes in three different steps. Finally, all the treated fruit were submitted to cold storage (5°C) for 12 days. Chemical-physical and sensory characteristics were analyzed after 4, 8 and 12 days of cold storage and their shelf life was monitored after 2 and 4 days at 20° C. Generally, the fruit submitted to RRF treatment presents a more intense red color in particular referring to L parameter and the best chemical-physical characteristics. Moreover, RRF fruit revealed having more consistency, juicy flesh, fruity flavour and exotic flavour after 4 days and of fruity odor and exotic odor after 8 days of cold storage. After 12 days, MAP and MAP+ showed a sensory decay. Finally, RRF technique, by rapid refrigeration, permits to prolong fruit color and taste during cold storage and consequent shelf life.

Quality Changes of Tropical and Subtropical Fresh-cut Fruits Mix in Modified Atmosphere Packaging

Application of passive modified atmosphere packaging (MAP) for shelf life extension of mixed pineapple slices, mango pieces and orange segments, was evaluated. Fruits of Ananas cv ‘Gold’, Mango cv ‘Keitt’ and Orange cv ‘Washington Navel’ were washed, sanitized, peeled and cut. Minimal processed fruits were packed under 2 different atmospheres, passive (air) and active MAP (70% N2, 10 %O2, 20 %CO2), and stored at 10±1 °C with 85±5% RH for 12 days. Changes in package atmosphere composition, weight loss, color, texture, pH, soluble solids, sensory attributes, were evaluated after cutting and at three subsequent stages of storage (the 3 day, 6d, 9d, and the 12 day). Color parameters L* and b* significantly decreased over time in all packaging conditions and L* variation was directly attributed to the translucency phenomenon in the fruit flesh. The pineapple and orange parameters highlighted the best visual score during the storage period, the lowest values of the browning index and the highest scores of all sensory descriptors at each sampling date. Organoleptic attributes have not been influenced by the storage time and no off-flavors were detected in the treated fruit. We conclude that pineapple slices and orange segments can be maintained in excellent condition for up 9 days at 10±1°C following the treatment with active MAP.

PREDICTION OF HARVEST TIME IN PEACH [PRUNUS PERSICA (L.) BATSCH] FRUIT USING THE DA-METER

The aim of this work was to define the most appropriate time of harvesting early ripening peach fruit using destructive and non-destructive quality indexes such as the index of absorbance (IAD), measured with the DA-Meter, a portable equipment able to measure the degradation of chlorophyll in the pericarp. In this context our research was carried out in 2009 and 2010 on several peach cultivars. Total soluble solid content increased while flesh firmness and total acidity decreased with IAD values, but no significant correlation was found between destructive and non-destructive parameters.

CO2 fluxes of Opuntia ficus-indica Mill. trees in relation to water status

Gas exchange pattern in O. ficus-indica (OFI), refers to the Crassulacean Acid Metabolism (CAM); trees have nocturnal stomata opening, so net CO2 uptake and water loss occur during the cooler part of the 24-hour cycle. Succulent cladodes skip severe periods of drought through their water storer tissue (parenchyma). To study carbon fluxes in stress and no stress conditions, an experiment was carried out on 3-year-old irrigated and non-irrigated OFI potted trees; whole tree gas exchange was measured continuously with a balloon system made up by a portable Infrared Gas Analyzer. Continuous measurements (nighttime) during the summer season were useful to assess differences in carbon uptake under stress and no stress conditions. There was a gradual increment (5 μmol m s in June, 7 μmol m s in July and 8.8 μmol m s in August) in terms of CO2 uptake in irrigated trees from June to August 2010. The uptake was lower in stressed trees than in irrigated ones in each measurements date. Measurements carried out on non-irrigated trees showed carbon gain even 60 days after irrigation was stopped, with less than 2% of soil water content, far below the wilting point. Considering an average of 6.9 μmol CO2 m s, for well watered trees, from June to August, and a stem area index (SAI) of 2, a daily amount of 21.8 kg ha d of CO2 was accumulated in irrigated trees in that period, corresponding to a carbon assimilation of 0.54 T ha. INTRODUCTION Opuntia ficus-indica (L.) Mill. is a CAM species (Crassulacean Acid Metabolism) belonging to Cactaceae family. This group of species shows nocturnal stomata opening and CO2 uptake. During the nighttime, through phosphoenolpyruvate (PEP) carboxylation, malate is formed and stored in vacuoles, while, during the daytime, stomata are closed, malate is decarboxylated and CO2 is fixed by Rubisco. In the early 1900s CO2 uptake was obtained through indirectly measurements; indeed, Richards (1915), monitored gas exchange analyzing day/night fluctuation of acidity in stem tissues sampled from dusk to dawn. Direct measurements of gas exchange in O. ficus-indica, however, began in the early 1980s, when Nobel and Hartsock (1984) measured CO2 uptake on single cladodes grown in growth chambers. From then onward, cladodes gas exchange measurements have been done on single portions of a cladode, at specific intervals (2-4 h) during the night, using a portable system with leaf chambers, adapted to cladode morphology. This system is affected by a large variability of spot measurements, and much depends on operator’s skill. Under optimal conditions (25/15°C day/night) and light saturation, OFI may assimilate 3.44 g m d CO2; three weeks of drought conditions are required for halving net CO2 uptake over 24-h periods (Nobel, 1988), and net CO2 uptake over 24-h period is around zero after 50 days of drought (Acevedo et al., 1983). Instantaneous values of net CO2 uptake of 1-year-old cladodes range from 4.5 to 15 μmol m s (Inglese et al., 1994; Pimienta-Barrios et al., 2005). Response of cladodes to drought also depends on newly developing cladodes; indeed, as the number of current-year cladodes increased, total daily