APPLE JUICE QUALITY AS INFLUENCED BY ULTRAFILTRATION

Objective quality of ultrafiltered (UF) apple juice compared favorably to apple juice filtered by conventional plate and frame filtration (PF). Agtron red and green values were higher for the UF juice, indicating a lighter colored product. Agtron green values were lower after 4 months of storage and compared well to juice from conventional methods over the remaining 8 months of storage. Green color of the UF juice remained steady at storage temperatures of either 1° or 21°C and was equal to the color values of the conventional juice stored at 1°, 21° or 32°. Clarity of the UF juice was excellent and remained stable over the entire storage period at either 1 or 21° with only a slight drop in clarity at 32°. UF juice was rated significantly lower in sensory flavor than PF juice. Sensory color of the UF juice was not rated as high as the PF juice at the start of the study, but as time in storage progressed sensory color improved. Initial panel reaction to UF apple juice was that the UF juice was too light in color and watery in flavor.     

APPLE QUALITY INFLUENCED BY TRIAZOLE GROWTH RETARDANTS

Four-year-old ‘Ace Delicious’ apple trees on seedling rootstock were treated by soil injection with the vegetative growth inhibitors paclobutrazol or triapenthenol (RSW0411) at the same rate in March 1984. Fruit from trees treated with paclobutrazol were firmer, and had higher soluble solids and lower acidity than both controls and fruit from RSW0411 treated trees. Values for fruit firmness, soluble solids and acidity from RSW0411 treated trees were between those of paclobutrazol and controls. Both compounds reduced fruit length and increased fruit diameter. However, length/diameter ratio was reduced 9% for paclobutrazol but only 5% for RSW0411. Neither compound reduced nor increased fruit disorders out of regular storage after 5 months at 0°C.     

QUALITY OF 'BOSC' PEARS AS INFLUENCED BY ELEVATED CARBON DIOXIDE STORAGE

‘Bosc’pears (Pyrus communis L.) were placed in a purge-type controlled–atmosphere (CA) storage immediately after harvest (>24 h) and held for 180 days at 1C. Oxygen in all atmospheres was 1.5% and CO₂ was 1%, 3% or 5%. Pears were evaluated immediately after removal from CA storage and after ripening for an additional 7 days at 21 C. Pears stored in 3% CO₂ were firmer, had a superior finish, with significantly reduced decay and internal breakdown than pears stored in 1% CO₂. In 3% CO₂, pears retained the ability to ripen after long-term storage. A 10 day delay in atmosphere establishment had little or no influence on the long-term keeping quality or ripening ability of ‘Bosc’pears. Firmness, soluble solids content and starch either alone or together were good indices of maturity for ‘Bosc’ pears.     

QUALITY OF MINIMALLY PROCESSED LETTUCE AS INFLUENCED BY PACKAGING AND CHEMICAL TREATMENT

Shredded lettuce was packaged in sealed bags of monooriented polypropylene (OPP) film and also in polyethylene (PE) trays overwrapped with a multilayer polyolefin (RD106) or plasticized polyvinyl chloride (PVC) film; and stored at 4C in a refrigerated case during 8 days. Chemical treatment by dipping in a 0.3% ascorbic acid /0.3% citric acid solution did not significantly affect changes in microbial populations or visual sensory attributes. Type of package was not a significant factor for microorganism populations, but was significant (p<0.001) for changes in gas composition and visual sensory attributes. The modified atmosphere within the packages changed from normal air composition to about 1.5% O₂/12% CO₂ for OPP bags and to about 17–18% O₂/1–2% CO₂ for PVC-PE trays and RD106-PE trays after 8 days of storage. The visual sensory quality of the product was retained better in OPP bags than in the other ones.     

SENSORY QUALITY OF GALA APPLES AS INFLUENCED BY CONTROLLED AND REGULAR ATMOSPHERE STORAGE

The sensory quality of Gala apples stored for up to 4 months in delayed controlled atmosphere (CA), regular atmosphere (RA), and a combination of sequential CA and RA storage (CR) was evaluated. Sensory analysis included difference and acceptance testing. Firmness, soluble solids and titratable acidity contents, and volatile flavor profiles were measured analytically. Acceptability decreased with storage time. Apples stored in RA were more acceptable than apples stored in CA or CR; the differences between storage treatment were not significant after 4 months of storage. Firmness decreased with storage time, but was not affected by storage treatment. Soluble solids and titratable acidity contents were not affected by storage treatment or time. Storage treatment, storage time, and lot had a significant effect on the volatile flavor profiles. CA storage and extended storage contributed to decreases in the content of volatile flavor compounds.     

QUALITY OF RESTRUCTURED PORK ROASTS AS INFLUENCED BY SALT, PHOSPHATE AND ROASTING ENVIRONMENT

A split plot design was used to evaluate the effect of 3 salt (0.0, 0.5, 1.0%), 3 phosphate (0.0, 0.25, 0.5%) levels and 2 roasting environments (moist, dry) on the quality of restructured pork roasts. Emulsion stability, yield (cooked or sliced), Instron adhesion (bind), pH, water holding capacity, proximate composition and color measurements were obtained. Increasing salt or phosphate level increased emulsion stability and cooked yield. Increasing salt level and the addition of phosphate decreased expressible moisture and increased slice count and moisture content. Increased levels of salt decreased protein content, while increasing phosphate, increased pH and redness in the cooked slices. Salt and phosphate reacted synergistically to increase slice yield and adhesion bind. Roasts cooked in a moist environment were lower in pH, were darker in color and required less time to cook. Restructured pork roast quality was enhanced when salt and phosphate were included in the formulation.     

FRESH AND PROCESSED ASPARAGUS QUALITY AS INFLUENCED BY FIELD GRADE1,2

Shear, moisture, and soluble solids values for either the all-green spears or those cut with a white butt portion are similar for either fresh or processed spears. Fresh asparagus spears cut all-green contain less ascorbic acid than spears cut with a white butt portion, but after processing no difference is evident. Small diameter spears are higher in ascorbic acid and shear values than large diameter spears. After processing, the shear values for the large diameter spears are higher than those for small diameter spears. Holding asparagus spears for extended periods of time results in decreased ascorbic acid and moisture content and increased shear values.     

FRESH–CUT SPINACH QUALITY AS INFLUENCED BY SPIN DRYING PARAMETERS

Abstract Response Surface Methodology was used to evaluate the effect of speed (0 to 1080 rpm) and operation time (1 to 9 min) of spin drying on the excess water remaining on washed, fresh–cut spinach, and microbial growth and sensory deterioration during storage of the spinach. The higher the centrifugal speed, the less water excess was present at a given time, centrifugal speed having a greater influence on water excess than operation time. The aerobic and psychrotrophic microbial counts were not affected by the drying conditions. By visual inspection of the contour plots, the region of minimum browning was obtained for centrifugal speeds between 700–750 rpm (equivalent to centrifugal forces from 65.8 to 75.5 G) and operation time from 5 to 5.5 min. Under these conditions, the water excess on the produce should range from 0.2 to 0.5%.     

QUALITY OF PACKED AND BIN STORED 'ANJOU' PEARS AS INFLUENCED BY STORAGE ATMOSPHERE AND TEMPERATURE

Packed pears (Pyrus communis‘d’‘Anjou’) were stored under four individual controlled atmosphere (CA) storage conditions (#1: CA of 1.5% O₂ and < 1% CO₂ at −1.5C; #2: CA of 1.5% O₂ and < 1% CO₂ at + 1.5C; #3: CA of 1.5% O₂ and 3.0% CO₂ at −1.5C; #4: CA of 1.5% O₂ and 3.0% CO₂ at + 1.5C). Loose pears in bins were stored under three CA storage conditions (#1: CA of 1.5% O₂ and <1% CO₂ at −1.5C; #2: CA of 1.5% O₂ and 3.0% CO₂ at −1.5C; #3: CA of 1.5% O₂ and 3.0% CO₂ at +1.5C). For packed pears, increased CO₂ in the storage atmosphere resulted in retention of peel color, reduced firmness loss and enhanced subjective scores, particularly for finish and stem condition. Pears stored loose in bins, prior to packing in late January in an atmosphere containing 3.0% CO₂ aided firmness retention, reduced scald and greatly enhanced subjective quality scores for appearance, finish and scuffing. Storing ‘Anjou’pears in a 3.0% CO₂ atmosphere allows for storing pears loose in bin and packing in late January with little or no quality losses compared with using the standard 1.0% CO₂ in the storage atmosphere.     

QUALITY OF MODIFIED ATMOSPHERE PACKAGED "BARTLETT" PEARS AS INFLUENCED BY TIME AND TYPE OF STORAGE

Commercially mature “Bartlett” pears for this study were obtained from local commercial packing facilities. In the first year, pears were packed in modified atmosphere bags and placed in boxes or packed normally (control) with an individual paper wrap around each pear plus a polyethylene liner in the box. Boxed pears from both types of packaging were stored in regular atmosphere (RA) storage at 1C for 30 or 90 days. In the second year, pears were packed normally and stored in both RA or controlled atmosphere (CA) storage for 45 or 90 days, or packed in modified atmosphere bags and stored in RA at 1C. After 45 days, normally packed pears from both RA and CA were removed from their initial storage, placed in modified atmosphere bags and returned to RA storage for an additional 45 days. Pears stored in modified atmosphere bags were superior in quality to normally packed pears stored only in RA storage and equal in quality to pears stored in CA for periods of 90 days. The quality of pears held in modified atmosphere bags under CA conditions deteriorated after only short periods of time (<45 days). Pears in modified atmosphere bags should be stored only in RA. Little or no quality advantage was evident if use of modified atmosphere bags was delayed regardless of prior storage type.     

QUALITY OF APPLE SLICES PROCESSED BY COMBINED TECHNIQUES

The effectiveness of single pretreatments and combinations of pretreatments on the prevention of enzymatic browning during freezing and thawing of apple slices was investigated. The combinations of blanching and dipping, either of which alone could not control enzyme activity, were studied. Blanching of apple slices caused a significant decrease of firmness even before the freezing-thawing phase. The use of a “light” dip after a short blanch allowed the product to be cooled and helped the antioxidant agents (ascorbic and citric acids) to enter apple tissue. The anti-browning action of sodium chloride, even at very low levels in dipping solutions, was confirmed. Partial drying avoided the loss of firmness but negatively affected the color. “Mild pretreatments”, including partial drying, gave satisfactory results in terms of firmness and color.     

TEXTURE PROFILE PARAMETERS OF COOKED FRANKFURTER EMULSIONS AS INFLUENCED BY COOKING TREATMENT2

Texture profile parameters of frankfurters were found to be generally related to cooking temperatures, except for degree of elasticity, hysteresis loss, and work ratio. Cohesiveness, elasticity, gumminess, and chewiness all were polynomial functions of cooking temperature and were smallest at 70-75° C where physico-chemical changes in proteins important to texture development appeared to be occurring. Hardness, compression energy of first bite, brittleness, apparent moduli of elasticity, stress at 20% compression and strain energy of compression per unit volume were all linearly related to the cooking temperature. Texture profile parameters were higher for samples with higher protein and lower moisture contents at all cooking temperatures.     

PECTIC SUBSTANCES AND FIRMNESS OF CUCUMBER PICKLES AS INFLUENCED BY CACL2, NACL AND BRINE STORAGE1

The effects of brine treatments (CaCl₂ and NaCl) and storage on pectic substances and texture of cucumber pickles were examined. Firmness of cucumber pickles was closely associated with the solubility characteristics and degree of esterification (DE) of pectic substances. Brining, storage, time of CaCl₂ addition and concentration of NaCl and CaCl₂ were all observed to influence the characteristics of pectic substances. Important to preventing softening was maintenance of pectic substances not extractable (NXP) by conventional methods, i.e., by water (WSP), the chelator sodium hex-ametaphosphate (CSP), and dilute alkali (OHSP). Erosion of NXP consistently resulted in increased levels of CSP and reduced firmness. Reducing the amount of demethylation of pectins was also associated with maintaining firmness. Although the DE declined rapidly during brining, tissues from treatments that enhanced firmness had pectic substances with the highest DE. CaCl₂ added to brine at the beginning of fermentation was most effective in preventing the demethylation of pectins and solubilization of NXP. In contrast, delayed addition of CaCl₂ and storage in low NaCl concentration (5% or less) caused greater pectin demethylation, erosion of NXP with concomitant increases in CSP and tissue softening.