EFFECT OF PACKAGING MATERIALS ON COLOR,VITAMIN C AND SENSORY QUALITY OF REFRIGERATED MANDARIN JUICE

ABSTRACT

Refrigerated mandarin juice was packed in four different containers, three cartons with different composition and one polyethylene terephthalate transparent bottle, and was stored at 4C for 90 days. During the storage of these juices, changes in the headspace gas composition, vitamin C, and CIE L*, a* and b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color, fresh mandarin flavor and presence of off‐flavors in the juices. Experimental data indicated that the deterioration of mandarin juices (ascorbic acid degradation and darkening of color) was triggered by the rise in oxygen in the headspace of the storage containers. The type of container played a predominant role in determining the juice quality, with carton containers with an inner layer of aluminum foil providing the juices with the best quality throughout their storage.

PRACTICAL APPLICATIONS

Results from this study will provide manufacturers of mandarin juice with information dealing with the storage and quality of juices packed in different containers. In this way, if manufacturers want to use transparent polyethylene terephthalate (PET) bottles showing the color and appearance of the juice, they will be aware that the shelf life of the juice will be much shorter than in packed cartons; this reduction will be from more than 90 to 36 days (PET bottle). On the other hand, if manufacturers want to use carton for their packaging, they will be aware that using a container with a thick inner layer of aluminum foil will maintain the quality of the juice for a longer time (over 90 days) compared with a shelf life of about 54 days from cartons with an inner layer of ethylene vinyl alcohol copolymers.     

超高压杀菌对鲜榨猕猴桃汁中Vc含量变化的影响

探讨了超高压杀菌过程中压强变化对鲜榨猕猴桃汁中Vc含量的影响。实验结果表明，经超高压处理后猕猴桃汁中的总Vc保存率在85％以上，还原型Vc在83％以上，保存率远远高于热力杀菌技术。     

EFFECT OF ACTIVATED CHARCOAL ON WATER-SOLUBLE VITAMIN CONTENT OF APPLE JUICE

The effect of activated charcoals (0, 0.5, 1.0, 2.0 and 3.0 g/L of powdered and granular activated charcoals) on the content of several water-soluble vitamins in apple juice was studied. Apple juice samples with activated carbon added were mixed for 0 (control), 5, 10, 20, and 30 min, respectively. The content of water-soluble vitamins was analyzed by HPLC. Considerable reduction in ascorbic acid (Vit C), niacin, pyridoxine (Vitamin B₆), thiamine (Vitamin B₁) and biotin concentrations was found while there was a dramatic improvement in the color and clearness of apple juice. The highest decrement in water-soluble vitamins was obtained at 3.0 g/L powdered activated charcoal. Statistical analysis of the data showed highly significant differences (P |< 0.05, P < 0.01) in the water soluble vitamins, color and clearness of the apple juice samples between the dosages of activated charcoals but no significant differences induced by the mixing periods.     

COLOR AND VITAMIN C CONTENT IN MANDARIN ORANGE JUICE AS AFFECTED BY PACKAGING MATERIAL AND STORAGE TEMPERATURE

Mandarin orange (Citrus reticulata) juice was packed in two different non-transparent cartons made of polyethylene, cardboard and (1) aluminum foil (Tetrapak ^® ) or (2) ethylene vinyl alcohol copolymers (Pure-pak ^® ) and was stored at 4C or room temperature (25  ±  3C). During the shelf life of these juices (35 days), changes in the headspace gas composition, vitamin C and CIEL*a*b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color of the juices. Mandarin orange juices darkened and ascorbic acid content decreased with storage time. Type of carton and storage temperature played a predominant role in determining the final juice quality, with Tetrapak ^® carton providing the juice with the best quality (intense orange color and high vitamin C content and consumer preference) throughout their shelf life.

PRACTICAL APPLICATIONS

This study was a clear example of how research can help real food companies in selecting the right materials for their production lines. In this particular case, the results presented show how Tetrapak^® packaging led to a final mandarin orange juice of higher quality compared to Pure-pak^® packaging. Therefore, citrus processing companies have some scientific data comparing the behavior of these two types of non-transparent cartons. Besides, the companies manufacturing these cartons also have some information about their materials and can use it to improve them.     

草莓汁加工贮藏过程中维生素C稳定性的研究

初步考察了影响草莓汁加工贮藏过程中维生素C变化的因素。采用正交试验法,以加工贮藏过程中维生素C的保存率为考察指标,对维生素C的变化进行了初步研究。结果表明,实验设计的三因素中含空气量对维生素C的变化有显著影响。最佳加工贮藏初步工艺为:采用热榨加工工艺,在15-18℃冷室,无氧贮藏方式。为草莓汁的进一步加工贮藏提供了理论依据。     

QUALITY OF MINIMALLY PROCESSED FRUITS AND VEGETABLES

Consumer demand for fresh fruits and vegetables coupled with a demand for convenience is fueling an interest in minimally processed products. Advances in packaging technology provide a potential for improved quality and extended shelf-life of these products, but little is known about the physiological, microbiological and nutritional consequences of minimal processing. Mass marketing and brand-label identification of these products will require a new perspective on shelf-life and quality assurance. A systems approach has been proposed as a framework for quality management of fresh and minimally processed product based on the concept of providing the consumer with optimum quality at purchase and consumption.     

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.     

STRENGTHS AND WEAKNESSES OF ASSESSING VITAMIN CONTENT OF FOODS

Significant advances have been made in vitamin assay methodology applicable to foods over the last 10 to 15 years. However, specific problem areas exist that continue to limit the availability of accurate nutrient data for many of the vitamins. This paper will discuss some of the recent advances made in vitamin assay methodology and some of the weaknesses to be overcome in the years ahead.     

QUALITY AND STABILITY OF BLUEBERRY JUICE BLENDED WITH APPLE,GRAPE AND CRANBERRY JUICE1

Sensory quality and storage stability of blueberry juice blends were investigated with the goal of maintaining dominant blueberry flavor, aroma and color. Apple juice, Concord and Venus grape juices and cranberry juice cocktail were blended at 75, 50 and 25% with blueberry juice. As the percent of blueberry juice decreased, the intensity of blueberry‐related sensory attributes decreased. The 25% Concord and Venus blends were the only blends that resulted in blueberry flavor similar to the reference. Apple and cranberry juice cocktail blended with blueberry juice produced several blends with good flavor and aroma, but they were not readily characterized as blueberry juice. All blends at the 25% level produced blueberry color equal to or greater than the reference. The juice samples were evaluated initially and after three months of storage at 37C. After storage, all blends had decreased red color.