EFFECT OF SONIC ENERGY ON THE AIR DRYING OF APPLE AND SWEET POTATO CUBES

Cubes (2 cc) of apple and sweet potato were dried with and without sound energy in air at velocities of 5 – 20 fps and temperatures of 125 – 175°F. A stem jet or electronic whistle provided sound energy at 9,800 and 13,000 Hz with an intensity up to 135 dB. Results indicated that sonic energy had no effect on drying rate under all experimental conditions.     

EFFECT OF VARIOUS DRYING METHODS ON TEXTURE AND COLOR OF TOMATO HALVES

Tomatoes were pretreated with osmotic solutions (NaCl and sucrose) at different concentrations and then dried using hot air (75C, 1.5 m/s), a vacuum (55C, 75 kPa) or hot-air drying followed by microwave treatment (400 W, 10 s). The effects of pretreatment and drying method on the drying kinetics were examined. A puncture test and scanning electron microscopy were used to analyze the effects of these processes on texture and microstructure. Hunter values ( L, a, b ) were used to measure color. Measurements showed that two osmotic solutions, S₃ (40% sucrose, 5% NaCl) and S₄ (40% sucrose, 10% NaCl), performed better, reducing drying times and having a positive effect on microstructure, but an adverse effect on hardness. Apart from the type of process, dehydration reduced firmness and collapsed the structure of tomato halves. The subsequent microwave treatment then caused further damage, especially on the surface of the dried samples, but enhanced their color when combined with appropriate osmotic treatment.

PRACTICAL APPLICATIONS

This study shows that the color and structural changes of tomato during drying can be reduced using appropriate procedure. This may find application in the production of dried tomato with better appearance and lower drying cost.     

INFLUENCE OF APPLE JUICE TREATMENTS ON THE CIDER MAKING PROCESS

This study was conducted to examine the influence of the following apple juice treatments on different parameters of cidermaking process: sulphiting (50 mg/L of total S0₂), clarification with pectolytic enzymes (Ultrazym 100 G, 3g/hL), and bentonite fining (lOOg/hL). The different treatments slowed down alcoholic fermentation, the greatest effect being found for the combination of the three treatments. With respect to malolactic fermentation, must sulphiting, with or without the other two treatments, delayed this process, which took place after alcoholic fermentation. The low levels of lactic acid bacteria during this period can explain this delay. The only treatment that had any significant influence on volatile acidity was sulphiting, either on its own or in combination with the other treatments. Thus lower acetic acid levels were detected in ciders treated with SO₂ .     

EFFECT OF SAMPLE WEIGHT AND ORIENTATION ON THE TEXTURE PRESS FORCE OF APPLE SLICES

Texture measurements of both fresh apple slices and steam-blanched apple slices were studied using the FTC Texture Press. Sample weights of 40, 70, 100, 130, and 160 g slices were tested and three orientations (crosswise, lengthwise and randomly) of slices in the standard shear compression cell. The maximum shearing force approaches a constant when the sample weight reaches 70 g for blanched slices. Sample weights of 100 g for fresh slices and 100–130 g for blanched slices are suggested by these test results. Crosswise or random orientation of slices in the cell is preferred. Polynominal models of the maximum force (N) versus sample weight (g) are given and shown to be a closer fit over simple linear models.     

EFFECT OF WATER ACTIVITY ON TEXTURE PROFILE PARAMETERS OF APPLE FLESH

Fresh apple with a water activity of approximately 0.99 was partially dehydrated, then equilibrated to nine water activity levels down to Aw 0.01. The water desorption isotherm, for apple is given. Instrumental texture profile analysis was performed at each Aw level. As the Aw decreased, hardness increased slowly, then rapidly at Aw 0.12 then decreased again at Aw 0.01; deformation first increased sharply then steadily decreased; springiness increased to Aw 0.33 then decreased; cohesiveness increased down to Aw 0.65, held steady to Aw 0.33 then decreased; gumminess and chewiness increased down to Aw 0.12 then decreased. Fracturability was present only at the extremes (Aw 0.99 and 0.01) and was absent at all other water activity, levels. Complex changes in textural properties occur as apple is dehydrated and most of these changes occur most rapidly near the BET monolayer level of water activity.     

EFFECT OF ULTRASONIC TREATMENTS ON THERMOACIDOPHILIC ALICYCLOBACILLUS ACIDOTERRESTRIS IN APPLE JUICE

The effect of ultrasonic treatments on Alicyclobacillus acidoterrestris in apple juice was investigated. In general, inactivation of the cells was more pronounced at an elevated power level and as the processing time increased. Approximately 60% of the cells were inactivated after treating the apple juice with 300-W ultrasound for 30 min. The reduction reached more than 80% when the juice was processed for 60 min. The linear inactivation rates ( D values) of ultrasound on A. acidoterrestris were both process- and strain-dependent. The lowest D value at 36.18 min was found when using 600-W ultrasound to treat the A30 strain isolated from the air of a commercial apple juice processing plant, whereas the strain isolated from apple juice concentrate was found most resistant against ultrasound. Changes of sugar content, acidity, haze and juice browning were noted after ultrasonic treatments but did not adversely alter the juice quality.

PRACTICAL APPLICATIONS

Characterization of the effects of ultrasonic treatments on thermoacidophilic Alicyclobacillus acidoterrestris provides better understanding of how ultrasound technology could assist in alleviating the hard-to-detect spoilage caused by this spore former. Although ultrasonic technology might not be suitable as a standalone unit operation to inactivate high cell loads, the process could be integrated with other thermal or nonthermal technologies to enhance processing efficiencies, consequently preventing microbial spoilage caused by A. acidoterrestris .     

EFFECT OF MOISTURE, SUGAR AND TERTIARY BUTYLHYDROQUINONE ON COLOR, TEXTURE AND MICROSTRUCTURE OF PEANUT PASTE

The effect of antioxidant, sugar, moisture and storage time on color, texture and microstructure of peanut paste were determined. The addition of 2 or 5% water resulted in decreased lightness (L*), hue angle (h°) and chroma (C) values, while tertiary butylhydroquinone (TBHQ) and sugar levels had no effect on color. Peanut pastes with added moisture had increased hardness, adhesiveness and chewiness, and lower cohesiveness and springiness compared with treatments with no added moisture. TBHQ was not a significant factor for texture, but hardness increased with the level of added sugar. Scanning electron micrographs and image analysis of light micrographs confirmed the presence of aggregation of protein bodies in 2 and 5% moisture treatments. The addition of sugar or TBHQ produced no measurable changes in microstructural features.     

EFFECT OF MANNITOL TREATMENT ON ULTRASOUND EMISSION DURING TEXTURE PROFILE ANALYSIS OF POTATO AND APPLE TISSUE

An ultrasound acoustic emission (AE) signal was recorded during texture profile analysis (TPA) of potato and apple tissue with different texture. The acoustic sensor was in contact with the sample through solid medium. Texture of the tissue was controlled by soaking it in different mannitol solutions. Both TPA and AE parameters change with the texture of potato and apple samples. However, correlation coefficients of linear regression of acoustic parameters are higher than TPA parameters and all of them are significant at a higher confidence level. Critical stress and strain indicate micro‐cracking of the material and they increase with decreasing tissue turgor. The ratio of the critical stress to hardness allows an analysis of sound duration. The sound lasts longer when the tissue is more turgid as a result of the decrease of critical stress to hardness ratio. Counts of AE recorded in the whole TPA test decreased logarithmically with tissue osmolality. The article showed that contact AE can be used for texture evaluation of potato and apple tissue.     

EFFECT OF CaCl2 AND CONVECTIVE-OSMOTIC DRYING ON TEXTURE AND PREFERENCE OF APPLE

Conventional air‐drying combined with osmotic dehydration was researched as a potential method for drying apple cubes of superior quality. Samples were pretreated with CaCl₂ at different temperatures and times. Pretreated apple cubes were dehydrated in a tray dryer. Then, osmotic dehydration with sucrose solutions was carried out. The curves for osmotic dehydration showed that the gain of solids was higher when 40% of water was removed by convective drying while the loss of weight was lower at the same level of dehydration at 65°Brix. Texture measurements indicated that the temperature of pretreatment affected the hardness and cohesiveness. Hardness values were higher at 40C, while cohesiveness values were lower at the same temperature. The CaCl₂ at a given temperature did not have a significant effect on texture. Sensory evaluation showed that samples pretreated at 25C and osmotically dried at 50°Brix had the higher preference by the judges.     

A STUDY OF PRESTORAGE HEAT TREATMENT EFFECT ON APPLE TEXTURE: DESTRUCTIVE AND NONDESTRUCTIVE MEASUREMENTS

Effects of prestorage heat treatment on the texture of three apple cultivars: 'Gloster,'Golden Delicious' and 'Jonagold' (Malus domestica Borkh.) were studied before and after heat treatments at different time-temperature combinations. Changes of apple firmness, extractable juice content, background color, soluble solids concentration (SSC) and pH values were determined after 4 months cold storage (2C, 95% RH). Prestorage heat treatment can inhibit 'Golden Delicious' softening during cold storage but less effective for 'Jonagold' apples. Severe internal browning was found for heat treated 'Gloster' apples after cold storage. Heat treatments had no benefit on apple juiciness maintenance. Heat treated apples showed more physiological disorders compared with the nontreated apples after 4 months cold storage. The effect of prestorage heat treatment seems to be cultivar dependent.     

INFLUENCE OF PRETREATMENTS AND BLANCHING TREATMENTS ON THE YIELD AND COLOR OF CANNED MUSHROOMS

Three factors in PSU-3S and SSV processes, i.e. soaking, cold storage, soaking again or vacuum hydration, which might increase the yield of canned mushrooms, were investigated. The results of experiments revealed that only cold storage time in these processes significantly affected the yield of canned mushrooms. The undesirable effect of PSU-3S or SSV processes on the color of canned mushrooms may be significantly remedied by acid blanching.     

VARIOUS BLANCHING TREATMENTS EFFECT FINAL TEXTURE AND TOTAL FIBER CONTENT OF PEELED PROCESSED ASPARAGUS

The effect of peeling and three different methods of blanching on the texture of white asparagus was studied. Texture was measured in terms of maximum shear force and cutting energy, and as total fiber content. Manual peeling reduced the required cutting force in the middle and basal sections of the spear; fiber content diminished due to the elimination of the outer, most heavily lignified, layers of stalk. Results suggest that blanching by progressive immersion in hot water may be a feasible method of maintaining uniformity in asparagus texture. Blanching in hot water vapor seems to provide for less tough spears.     

FOOD GRADE HIDE COLLAGEN IN BOLOGNA EFFECT ON FUNCTIONAL PROPERTIES, TEXTURE AND COLOR

Bolognas were made in which 20% of the lean meat (beef and pork) was replaced by wet fibrous hide collagen and formulated to contain approximately 30, 20 or 10 percent fat in the final product. All meat controls (no collagen) were made to have similar fat content. Objective methods were used to analyze the product and paired comparisons of the data were made. The replacement of lean meat with hide collagen did not alter the functional characters such as raw emulsion stability andpH; cook yield, pH, water activity, density and expressible juice of the cooked bologna. The bolognas with collagen had higher (P<0.05) texture (increased Shear force value) compared to bologna with no collagen. As the fat content decreased the bolognas with collagen were less (P<0.05) red in color than the bolognas without collagen. The textural and color changes though detected on instrumental analysis were not perceptible on visual examination of the product.     

EFFECT OF PROCESSING ON NUTRIENT COMPOSITION AND TEXTURE OF PRUNES

Skin texture was influence by hydration procedure with the methods requiring the longest time at high temperatures producing the tenderest skin. The texture of freshly hydrated prunes continued to change during the first 6–15 weeks of storage. Hydration method had a pronounced effect on the nutrient composition and texture of prunes. No vitamin A loss occurred when prunes were hydrated by a high temperature short time process, compared to an 18% loss in the slower procedures. The skin of the prune contained more vitamin A and iron than the pulp.     

苹果多酚的乙醇提取和大孔树脂纯化工艺研究

研究乙醇提取和大孔树脂纯化苹果多酚的工艺条件.通过单因素和多因素试验考察操作条件对乙醇提取率的影响因素;利用静态试验考察大孔树脂纯化苹果多酚的吸附性能和洗脱参数.试验结果表明,乙醇提取苹果多酚的最优工艺条件为乙醇浓度80%,提取温度80℃,料液比1:3(g/L),总提取时间为60min;XDA-7型树脂纯化苹果多酚的最优工艺条件为吸附温度25℃、时间为2h,提取液浓度为0.50 g/L-0.60g/L、pH值为5,解吸温度30℃,解吸液为70%的乙醇溶液.     

INFLUENCE of BLANCHING TREATMENTS ON the TEXTURE and COLOR of SOME PROCESSED VEGETABLES and FRUITS

Fifteen selected vegetables and fruits were processed by conventional procedures with modified blanching conditions. the texture of blanched and processed samples was determined. Low-Temperature-Long-Time (LTLT) blanching considerably increased the final firmness of sterilized carrot, endive and green bean samples, as well as pasteurized cherry samples. After screening experiments, green bean and endive were chosen for further research. Analysis of variance revealed that LTLT blanching treatments in a blanching solution containing calcium and zinc cation significantly affected the texture and color of processed green bean and endive. the blanching treatments were optimized to improve the texture and color of sterilized green bean and endive.     

EFFECT OF VACUUM PACKAGING ON THE COLOR OF FROZEN SUGAR APPLE (ANNONA SQUAMOSA L.)

Sugar apples at 70–80 % of ripeness were individually quick frozen, with or without vacuum packaging, and stored for 12 months. Insignificant discoloration was observed in the vacuum‐packed samples, while serious change was observed in the control (nonvacuum‐packed samples). The main phenolic compounds in the sugar apples at 4 degree maturity were determined to be (+) catechin (272.9 ppm), chlorogenic acid (84.7 ppm), eugenol (21.3 ppm) and gallic acid (15.9 ppm). Fruits with higher maturity exhibited higher polyphenoloxidase (PPO) activity. However, PPO activity decreased the longer the storage period, especially in the nonvacuum‐packed fruits. Residual contents of those four phenolic components and of chlorophyll in the vacuum‐packed sugar apples were higher than those in the nonvacuum‐packed fruits during frozen storage.     

EFFECT OF HIGH PRESSURE TREATMENTS ON PEROXIDASE AND POLYPHENOLOXIDASE ACTIVITIES

The effects of hydrostatic pressure of 1–9 kbar on peroxidase (POD) and polyphenoloxidase (PPO) activity were studied. Trials were carried out on crude enzymatic extracts obtained from carrots and apples as the sources of POD and PPO, respectively, with different pH values (from 4.5 to 7.0). In both cases pressurization caused a remarkable enzyme activation after 1-min treatments carried out at 3–5 kbar, while a complete enzyme inactivation was observed at 9 kbar. The pH values of the crude enzymatic extracts seemed to affect the degree of activation and/or inactivation due to different pressure levels. A slight recovery in enzyme activity was measured for POD samples during the first 24 h of storage after the treatments.