STABILITY OF GUAVA PUREE CONCENTRATE DURING REFRIGERATED STORAGE

SUMMARY— Guava puree concentrate, containing 1000 ppm potassium sorbate, showed no gross signs of spoilage during storage for 5 months at 45°F. During this period, the initial number of yeasts (the predominant spoilage organisms) decreased steadily to an insignificant level. Flavor and aroma quality were good and did not deteriorate appreciably until the fourth month of storage. Browning of the concentrate was apparent after 2 months and became more pronounced with continued storage. The browning may be related to a rapid loss of ascorbic acid that was virtually complete after 1 month. The carotenoid level, on the other hand, remained constant during the 5-month storage period.     

EFFECT OF ORANGE JUICE COMPOSITION ON FLOW BEHAVIOUR OF SIX-FOLD CONCENTRATE

Abstract. The effect of the pulp content and the relative viscosity of the serum on the flow behaviour of a six-fold orange juice concentrate, as represented by the generalized Casson equation and the power law, was studied on samples prepared with a single factor varied at a time. These general flow equations, optimal in terms of multiple correlation coefficients, were established and confirmed on commercial samples. Both equations were successfully applied in predicting the flow behaviour of orange juice concentrates. The generalized Casson equation was found to be somewhat more accurate than the power law.     

STORAGE DETERIORATION OF FREEZE-DRIED AVOCADO PUREE AND GUACAMOLE

SUMMARY— The effect of storage temperature, time and atmosphere on the chemical and organo-leptic characteristics of freeze-dried avocado puree and guacamole was studied using Waldin, Lula and Booth-8 varieties of avocado. Oxidation rates were slower at 21°C than at 38°% storage and nitrogen atmospheres reduced the peroxide formation. Significant differences existed in oxidation rates between avocado varieties and also between guacamole and avocado puree in some instances. A logarithmic relationship was found between peroxide values and storage time in air. Guacamole made with Lula avocados was unacceptable after 3 weeks of storage in air at 38°C. Samples stored in nitrogen at 38°C ware unacceptable at the end of 7 weeks. Samples stored in air at 21°Cwere acceptable after 12 weeks and those stored in nitrogen at 2l°C after 15 weeks. A commercial BHA antioxidant reduced the oxidation rate of Lula puree but did not increase shelf life in air storage at 38°C. Peroxide values were of no use in predicting acceptability, since organoleptic deterioration could occur without any peroxide increase.     

CHARACTERIZATION OF THE TEXTURE AND FLAVOR PROFILES OF HAZELNUT PUREE

Flavor and textural characteristics of three commercially produced hazelnut purees, roasted at 120, 140 and 150C, respectively and ground to different particle sizes were determined using flavor and texture profiling. Instrumental color and texture values and particle sizes were also determined. The texture profile was evaluated by using 14 texture attributes: heaviness, wetness, slipperiness, oiliness, melting, viscosity, spreadability, cohesiveness, adhesiveness, smoothness, grainy, gumminess, mouth coating ability and overall acceptability. The flavor profile was evaluated using 10 flavor attributes: roasted, burnt, rancid, raw hazelnut flavors, sweetness, aroma, strength of taste, tongue sting, aftertaste and overall acceptability. The scores indicate that hazelnut puree is a viscous and heavy product with high adhesiveness and mouth‐coating ability but is not significantly cohesive. Its taste and aroma were characterized by roasted and raw hazelnut flavors, significant tongue sting and an aftertaste.     

FLOW BEHAVIOR OF GUAVA PUREE AS A FUNCTION OF TEMPERATURE AND CONCENTRATION

Flow behavior of guava puree was determined with a tube viscometer. The puree samples (9.8-16.0° Brix) exhibited shear-thinning behavior. The flow behavior index of the power law model was nearly constant for all the samples over a temperature range of 25-60°C; its mean value was 0.43 with a standard deviation of 0.031. The apparent viscosity decreased with increase in temperature and the activation energy offlow was found to be 3.7 kcallg mole. The apparent viscosity increased as the concentration of the purees was increased; the increase was proportional to concentration raised to a power of 2.7. The Mizrahi-Berk model described well the flow data of the purees. The magnitude of the shear rate exponent was about 0.48, indicating that the purees were suspensions in shearthinning media.     

COMPOSITION AND QUALITY OF CLARIFIED CANTAAOUPE JUICE CONCENTRATE

Cantaloupe fruit was processed into clarified juice and juice concentrate. Greater yields were obtained from pressing fruit containing the rind in contrast to pressing cantaloupe flesh with the rind removed. Juice pressed from cantaloupe flesh without rind was particularly difficult to filter, filtration being easier if the flesh had been frozen and thawed. Juice compositional measurements included °Brix, pH, titratable acidity (TA), formol values, ascorbic acid content, total carotenoids, browning indices, sugars, and nonvolatile acids. Ascorbic acid degraded rapidly during processing. Concentrates stored at 25C for 120 days showed extremely high rates of browning. Sensory evaluation demonstrated that rind aroma and flavor were removed during concentration. The high juice yields (ca. 80%), low TA (0.04 g/100 mL as citric acid) and sweet, fruity flavor suggest the potential use of clarified cantaloupe juice concentrate as an alternate sweetener and blended juice base.     

EFFECTS OF PHOMOPSIS PEACH ROT ON PULP LOSSES AND PUREE QUALITY

The effects of a Phomopsis sp. on four peach (Primus persica) cultivars and three fruit maturities were evaluated for pulp losses and quality changes of peach puree. Fruits were inoculated with 2 mm × 2 mm of agar with Phomopsis mycelium and incubated at room temperature (24 to 26 C) for 3 days. The early-maturing cultivar Goldilocks had higher susceptibility to Phomopsis than the late maturing Babygold 8. Mature fruit had a slightly higher degree of susceptibility to Phomopsis than less mature fruit, except for Goldilocks, which showed equal susceptibility at all maturity stages. Pulp losses, percentage of decayed tissue, titratable acidity, Howard mold counts, soluble solids (SS), SS/acid ratio, viscosity, pH and changes in color were variable among cultivars and maturities. Puree made with 1% or more Phomopsis-decayed tissue may be unacceptable because of a high (16–75%) mold count.     

柑橘加工废料综合利用现状及发展前景

综述利用柑橘类加工废料（果皮、果渣和果籽）提取香精油、果胶、天然色素、膳食纤维、类柠檬苦素等的研究现状,并对我国柑橘加工废料的发展前景进行展望。