CHLORINATED WATER TREATMENTS AFFECTS POSTHARVEST QUALITY OF GREEN BELL PEPPERS

Green bell peppers (cv. Bell boy) were dipped in 0, 50, 100, 150 and 200 μg/mL chlorine solutions for 20, 30 and 45 min to study the effect of chlorine on pepper quality characteristics. Chlorinated water treatments as well as dipping time had no major effect on external color or total sugar content of green peppers. However, total chlorophyll soluble solids content and ascorbic acid content decreased with increasing time of dipping and chlorine concentration. A 20 min dipping time in 50 to 100 μg/mL chlorinated solutions can be used without reducing the overall quality of green bell pepper.     

THE EFFECT OF POSTHARVEST HANDLING TECHNIQUES ON CANNERY YIELDS OF PIMIENTO PEPPERS

A damage classification scheme was developed and used to assess postharvest handling of pimiento peppers. Mass losses due to evaporation were lowered by removing the stem at the calyx. Greater moisture losses were observed at 27°C and 45% RH than 37°C and 65% RH in all damage classes except microbial invasion. Greatest peeling-yield losses were observed in classes which permitted lye penetration of the cuticle (mechanical, bacterial, and fungal damage). A model equation was developed to predict yield based on the lye concentration, average pepper weight and the percentages of fruit in each of five damage classifications (whole sound, shrivel, mechanical, bacterial and fungal). Removal of the stem during harvest, careful screening of fruit at the receiving station, and damage evaluation of incoming loads should result in improved pimiento processing yields.     

OPTIMIZING THE DEHYDRATION CONDITIONS OF GREEN BELL PEPPERS (CAPSICUM ANNUUM L.): QUALITY CRITERIA

Green bett pepper (Capsicum annuumL.) dices were dehydrated at different dry bulb air temperatures (55, 60, 65, 70 and 75C) and relative humidities (15, 20, 25, 30, 35 and 40%). Color, L-ascorbic acid and sugar retention were adversely affected by temperature and RH during dehydration. Loss of color and reduction in L-ascorbic acid and sugar were more prominent at the higher temperatures (70 and 75C) used. Sugar retention was negatively affected by drying, in that levels decreased, but no distinguishable pattern existed between the drying conditions and sugar retention. Optimum quality (maximum retention of color and L-ascorbic acid) green peppers were attained at drying conditions of 55 and 60C (15–40% RH) as well as at 65 and 70C (15% RH).     

STORAGE QUALITY OF BELL PEPPERS PRETREATED WITH HOT WATER AND POLYETHYLENE PACKAGING

Treatments of bell peppers (Capsicum annuum, L) with hot water at 45Cfor 15 min or SSC for 4 min prior to storage at 8C markedly reduced the incidence of fungal infections. However, the hot water treatment induced shriveling during storage. When hot water treated pepper fruits were subsequently placed in low density polyethylene bags, storage quality of these peppers improved tremendously including retention of firmness, reduction of water loss, retardation of color change, and alleviation of chilling injury. Total soluble solids, titratable acidity, and pH values in the pepper fruit were generally not affected by these treatment. A 4 min dip at 53C followed by packaging with 0.065 mm low density polyethylene film was very effective in maintaining pepper quality. This treatment inhibited respiration rate, reduced decay, retained turgidity and green color, and maintained excellent overall quality after 28 days of storage at 8C. Hot water treatment combined with polyethylene film packaging is a promising technique for improving the storage quality of bell peppers.     

EFFECT OF STORAGE CONDITIONS, PACKAGING MATERIAL AND METABISULPHITE TREATMENT ON THE COLOR OF DEHYDRATED GREEN BELL PEPPERS (CAPSICUM ANNUUM L.)

Green bell pepper dices were dipped in two metabisulphite solutions, 2400 and 3600 mg. kg‐¹, respectively, and dehydrated. The dehydrated peppers were sealed in laminated pouches of different oxygen and moisture transmission rates, and stored in the dark at 0, 10 and 20C for 12 weeks. Color was evaluated by objective color measurement and a sensory panel during storage. The different packaging materials did not significantly influence color retention, while the SO₂ treatments showed only limited differences in their effect, but storage temperatures significantly affected visual and objective color. The best correlation between visual color evaluation and the objective color measurements, was obtained for the a* (greenness) measurements. Panelists could discriminate between samples stored at 0 and 10C in contrast to a* measurements which did not differ significantly. Calculated hue angles exhibited the highest discriminatory ability of any of the objective color parameters.     

EFFECT OF IMMATURE AND OFF-COLORED SEEDS ON THE LIPID QUALITY OF MILLED FLAXSEED

The effect of visibly inferior flaxseed ( Linum usitatissimum L.) on the lipid quality of milled flaxseed was investigated. Flaxseed was aspirated and separated into low-, medium- and high-density fractions. All density fractions contained ≤ 0.1% broken seed, ≤ 0.4% contrasting seed and ≤ 0.25% extraneous material. The low-density fraction contained the most immature (2.8%) and off-colored seed (4.1%). Immature seed had a lipid content of 40.8%, a peroxide value (PV) of 2.69 meq/kg and a free fatty acid (FFA) content of 1.06%. The off-colored seed had a lipid content of 38.1%, a PV of 5.79 meq/kg, and a FFA content of 1.89%. Hand-cleaned seed (averaged across fraction density) had a lipid content of 41.4%, a PV of 0.41 meq/kg and FFA content of 0.37%. The removal of seed defects improved flaxseed quality and improved lipid quality in the low-density fraction.

PRACTICAL APPLICATIONS

Lipid oxidation is a major concern when using milled flaxseed as a food ingredient. These results indicate the importance of removing off-colored and immature flaxseed. Seed lots that contain immature and off-colored seed likely will have poor lipid quality and, when milled, be more susceptible to lipid oxidation during storage than will seed lots free of immature and off-colored seed.     

EFFECT OF COOLING DELAY AT HARVEST ON BROCCOLI QUALITY DURING POSTHARVEST STORAGE

Broccoli (cv ‘Green Duke’) was grown, harvested and cooled prior to simulated handling and storage. Delays of cooling were 0.5 and 3.0 h in one experiment and 0.5, 1 and 2 h in a subsequent experiment. Significant losses in market life of fresh broccoli were noted within the 3 h cooling delay period. Floret opening was the limiting visual quality characteristic in most treatments. Turgor was more limiting than color in all observed treatments. Using a systems approach a vertically-integrated broccoli handler could project the effects of cooling delays on shelf-life expectations within the prescribed handling system.     

EFFECT OF MOIST HOT AIR TREATMENT ON SOME POSTHARVEST QUALITY ATTRIBUTES OF STRAWBERRIES

‘Northeaster’ strawberries were heated with moist hot air at 36, 39, 42, 45, 50 and 55C for 0, 20,40, 60, 80 or 100 min. Fruit were injured when exposed to temperatures 50C or higher, or durations of 60 min or longer at 45C. Treatment at 45C for 40 min or at 42C for 60–100 min resulted in the least decay incidence after 5 days at 0C, 3 days at 10C, and 1 day at 20C. Heated strawberries in general had lower titratable acidity, higher soluble solids content and higher levels of fructose, glucose, and sucrose than nonheated samples. Heated fruit also had a higher soluble solids/acid ratio, but lower citric acid and malic acid content. The lightness measurements, L*, and chroma values, C*, were decreased by moist hot air treatment and the fruit were duller and less bright in appearance after heat treatment. Strawberries heated at 39C or lower temperatures had no discernable differences from nontreated fruit in quality attributes measured. However, fruit treated with 45C for 40 min or 42C for 60–100 min maintained better postharvest quality than other treatments.     

THE EFFECT OF COATINGS AND PROCESSING METHODS ON DEHYDRATED PRECOOKED WHOLE PINTO BEANS QUALITY1

Splitting is a major problem in preparing dehydrated precooked beans. To reduce splitting and improve the product quality of precooked pinto beans, three coating treatments and two processing methods were investigated. Beans were blanched, soaked, steam precooked, coated by dipping in a biopolymer solution, and dehydrated in an air-circulating dryer. Coating beans in a 20% dextrin solution (Lo-Dex 5, M100, or K4484) reduced 43–85% of butterflying (severe splitting) of beans. Steam precooking at 121C/30 min with soaking at 22C/12 h yielded less butterflying than steam precooking at 100C/1 h with soaking at 30C/2 h and 82 C/1 h after coating and dehydration (?3% vs 8%). The former resulted in lower firmness after precooking and rehydration of dehydrated beans, whereas the latter gave beans a more mealy texture and better appearance. The rehydration time of dehydrated precooked beans in boiling water to produce an acceptable firmness was 6–9 min, depending on the processing methods. Coating resulted in darker color and slower rehydration of dehydrated beans.     

A COMPARISON OF THREE INSTRUMENTAL TECHNIQUES TO EVALUATE BUTTER SPREADABILITY

Three instrumental techniques, cone penetrometry, probe penetration and Instron TPA, were compared as means to describe butter spreadability. A factorial experiment was set up to examine the consistency of winter and summer butter, mechanically worked and unworked, before and after storage and at two measurement temperatures, 5° C and 15° C. Probe penetration provided useful information on the relaxation behavior of butter, as well as contributing to the fundamental knowledge of butter structure. The Instron TPA has the advantage of a link with an internationally recognized system of texture analysis. The technique was also found to show greatest potential as a method to assess the effectiveness of mechanical treatment of butter. Cone penetrometry results were converted to yield values and in conjunction with Haighton's ready reckoner scale of assessment provided a simple and rapid method to describe butter spreadability.     

EFFECT OF POSTHARVEST HOT AIR AND FUNGICIDE TREATMENTS ON THE QUALITY OF 'MARADOL' PAPAYA (CARICA PAPAYA L.)

Papaya (Carica papaya L.) fruit is very perishable with a maximum postharvest life of 4 weeks. The effect of forced moist (100% RH) or dry (50%) hot air with or without Thiabendazole (TBZ at 1.2 g active ingredient/L) on the chilling injury (CI), fungi development and quality of ‘Maradol’papaya fruit stored at 5C or 20C for up to 42 days was investigated. Moist hot air at 48.5C or 50C for 4 h caused fruit injury. Dry air at 48.5C for 4 h, alone or in combination with TBZ, decreased CI intensity and fungi development, and the best effect was achieved by combining dry heat treatment and TBZ, without causing negative effects on fruit quality and without causing heat injury. Hot air treatment, especially in combination with TBZ, decreased growth of inoculated Colletotrichum gloeosporioides. Trehalose was not detected in papaya, probably due to the presence of trehalase. Hot water treatment, with or without TBZ, did not cause any negative effect on the content of β-carotene and lycopene.     

EDIBLE COATINGS ON FRESH SQUASH SLICES: EFFECT OF FILM DRYING TEMPERATURE ON THE NUTRITIONAL AND MICROBIOLOGICAL QUALITY

The exposure of foods to the temperature and humidity needed to dry the coatings can have deleterious effects on their quality. A critical analysis of the film drying conditions on quality indexes for butternut squash slices is presented. During the coatings drying, the samples lost significant amounts of weight and ascorbic acid. Only during the drying of the chitosan coating for 100 min at 20C and for 30 min at 50C that the ascorbic acid contents were not significantly reduced. The application of casein and carboxy methyl cellulose coatings did not cause significant reductions in the counts of mesophilic aerobic microorganisms (5.75–6.00 Log CFU/g). Chitosan coated samples presented significant log reductions showing the higher reductions the samples dried for 30 min at 50C (5.02 Log CFU/g). For the preservation of the nutritional and microbiological quality indexes of squash slices, the best coating conditions would be chitosan dried for 30 min at 50C.

PRACTICAL APPLICATIONS

The continuous consumer interest in high quality and food safety, combined with environmental concern, has induced the development and study of new edible coatings that avoid the use of synthetic materials. The edible coatings, formed from Generally Recognized as Safe materials, have the potential to reduce weight loss, respiration rate and improve food appearance and integrity. It is one of the most effective methods to maintain food quality.
Antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit or delay the growth of microorganisms on the surface of food in contact with the packaged products. In addition, the edible coatings allow the incorporation of food additives with antimicrobial effects that might help reduce microbial spoilage during postharvest.     

EFFECT OF SALTING AND SMOKING METHOD ON THE STABILITY OF LIPID AND MICROBIOLOGICAL QUALITY OF NILE PERCH (Lates niloticus)

Nile perch fillets treated with two brine concentrations (250g/L and 80g/L) and smoked by two different methods (hot and cold smoking) were stored at 2C for a period of three weeks. The rate of lipid oxidation during storage was observed to be a function of brine concentration and method of smoking. Lipids were more stable in cold than hot smoked fillet. Total phenolic compounds were inversely correlated with the degree of lipid oxidation. The strength of brine affected the bacterial profile of the stored fish; temperature affected both bacterial growth and lipid oxidation during storage.     

INFLUENCE OF HIGH TEMPERATURE STRESS ON POSTHARVEST QUALITY OF PROCESSING AND NON-PROCESSING TOMATO CULTIVARS

Tomato fruits from a processing cultivar,‘Dorado’and a non-processing cultivar, ‘Star Pak’, were subjected to three prestorage heat treatments over a 5-h period under unshaded (34±2C), shaded (29±2C) and pre-cooled (20±2C) conditions followed by storage for 18 and 36 days at 20C. Terminal symptoms of heat injury and disease infection were evaluated in relation to changes in physical, physiological and chemical characteristics of the fruits during storage. Unshaded fruits demonstrated effects of heat injury resulting in reduced bioelectrical resistance, increased electrolyte leakage, increased total acidity and decreased total soluble solids during storage at 20C. Pre-cooling and shading proved to be effective methods to remove or prevent accumulation of field-heat and minimize heat injury. Pre-cooling was most effective, accounting for 28 % and 14% less infected fruits for ‘Dorado’and ‘Star Pak’, respectively, compared with unshaded fruits, after 36 days storage at 20C.