Pomegranate juice: a heart-healthy fruit juice
Pomegranate juice is a polyphenol-rich fruit juice with high antioxidant capacity. In limited studies in human and murine models, pomegranate juice has been shown to exert significant antiatherogenic, antioxidant, antihypertensive, and anti-inflammatory effects. Pomegranate juice significantly reduced atherosclerotic lesion areas in immune-deficient mice and intima media thickness in cardiac patients on medications. It also decreased lipid peroxidation in patients with type 2 diabetes, and systolic blood pressure and serum angiotensin converting enzyme activity in hypertensive patients. Thus, the potential cardioprotective benefits of pomegranate juice deserve further clinical investigation, and evidence to date suggests it may be prudent to include this fruit juice in a heart-healthy diet.[1]
Fruit juice consumption by infants and children: a review.
The pattern of fruit juice consumption has changed over time. Fifty years ago, orange juice was the major juice produced and it was consumed primarily to prevent scurvy. Now, apple juice is the juice of choice for the under 5 age group. While fruit juice is a healthy, low-fat, nutritious beverage, there have been some health concerns regarding juice consumption. Nursing bottle caries have long been recognized as a consequence of feeding juice in bottles, using the bottle as a pacifier, and prolonged bottle feeding. Non-specific chronic diarrhea or “toddler’s” diarrhea has been associated with juice consumption, especially juices high in sorbitol and those with a high fructose to glucose ratio. This relates to carbohydrate malabsorption, which varies by the type, concentration, and mixture of sugars present in different fruit juices. Fruit juice consumption by preschoolers has recently increased from 3.2 to about 5.5 fl oz/day. Consumption of fruit juice helps fulfill the recommendation to eat more fruits and vegetables, with fruit juice accounting for 50% of all fruit servings consumed by children, aged 2 through 18 years, and 1/3 of all fruits and vegetables consumed by preschoolers. Concomitant with the increase in fruit juice consumption has been a decline in milk intake. This is concerning as milk is the major source of calcium in the diet, and at present, only 50% of children, aged 1 through 5 years, meet the RDA for calcium. Studies of newborn infants and preschool-aged children have demonstrated a preference for sweet-tasting foods and beverages. Thus, it is not surprising that some children, if given the opportunity, might consume more fruit juice than is considered optimal. Eleven percent of healthy preschoolers consumed > or = 12 fl oz/day of fruit juice, which is considered excessive. Excess fruit juice consumption has been reported as a contributing factor in some children with nonorganic failure to thrive and in some children with decreased stature. In other children, excessive fruit juice consumption has been associated with an increased caloric intake and obesity. This paper reviews the role of fruit juice in the diets of infants and children and outlines areas for future research. Recommendations regarding fruit juice consumption based on current data are also given.[2]
Fruit Juice Processing and Membrane Technology Application
This article provides an overview of recent developments and the published literature in membrane technology with regard to fruit juice processing and considers the impact of such technology on product quality. In the fruit juice industry, membrane technology is used mainly to clarify the juice by means of ultrafiltration and microfiltration and to concentrate it by means of nanofiltration and reverse osmosis. We look at enzyme immobilization techniques to improve filtration performance and operation methods to quantify fouling. Membrane fouling is a critical issue and inhibits the broader application of membranes in the fruit production industry. Pectin and its derivatives form a gel-like structure over the membrane surface, thereby reducing the permeate flux. In order to degrade pectin, the raw juice is usually subjected to an enzymatic treatment with pectinase, which hydrolyses pectin and causes its protein complexes to flocculate. The resulting juice has reduced viscosity and a much lower pectin content, which is advantageous in the subsequent filtration processes.[3]
Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products
Background and Purpose: Knowledge of the citric acid content of beverages may be useful in nutrition therapy for calcium urolithiasis, especially among patients with hypocitraturia. Citrate is a naturally-occurring inhibitor of urinary crystallization; achieving therapeutic urinary citrate concentration is one clinical target in the medical management of calcium urolithiasis. When provided as fluids, beverages containing citric acid add to the total volume of urine, reducing its saturation of calcium and other crystals, and may enhance urinary citrate excretion. Information on the citric acid content of fruit juices and commercially-available formulations is not widely known. We evaluated the citric acid concentration of various fruit juices.
Materials and Methods: The citric acid content of 21 commercially-available juices and juice concentrates and the juice of three types of fruits was analyzed using ion chromatography.
Results: Lemon juice and lime juice are rich sources of citric acid, containing 1.44 and 1.38 g/oz, respectively. Lemon and lime juice concentrates contain 1.10 and 1.06 g/oz, respectively. The citric acid content of commercially available lemonade and other juice products varies widely, ranging from 0.03 to 0.22 g/oz.
Conclusions: Lemon and lime juice, both from the fresh fruit and from juice concentrates, provide more citric acid per liter than ready-to-consume grapefruit juice, ready-to-consume orange juice, and orange juice squeezed from the fruit. Ready-to-consume lemonade formulations and those requiring mixing with water contain ≤6 times the citric acid, on an ounce-for-ounce basis, of lemon and lime juice.[4]Fruit juice processing using membrane technology: A review
Membrane technology has emerged as a substitute to traditional juice clarification and concentration processes as they require less manpower, reduce operating cost and low temperature. It is a low temperature process in which the organoleptic quality of the juice is almost retained. The advantages of these membrane processes over traditional methods are lower thermal damage to product, increase in aroma retention, less energy consumption, and lower equipment costs. Membrane concentration of fruit juice not only provides microbiological stability but also permits economy in packaging and distribution of the finished product due to a reduction in bulk by weight and volume. The biggest problem in the use of membrane based processes for the clarification/concentration of fruit juices is membrane fouling. Membrane fouling manifests itself as a decline in flux with the time of operation, reducing the membrane permeability. The degree of membrane fouling determines the frequency of cleaning, the lifetime of the membrane, the membrane area needed and consequently costs, design and operation of membrane plants. In this review, different membrane separation methods including microfiltration, ultrafiltration, nanofiltration and reverse osmosis for fruit juice clarification/concentration reported in the literature in the last fifteen years are discussed. Membrane Distillation methods for juice concentration is also covered in this review.[5]
Reference
[1] Basu, A. and Penugonda, K., 2009. Pomegranate juice: a heart-healthy fruit juice. Nutrition reviews, 67(1), pp.49-56.
[2] Dennison, B.A., 1996. Fruit juice consumption by infants and children: a review. Journal of the American College of Nutrition, 15(sup5), pp.4S-11S.
[3] Echavarría, A.P., Torras, C., Pagán, J. and Ibarz, A., 2011. Fruit juice processing and membrane technology application. Food Engineering Reviews, 3(3), pp.136-158.
[4] Penniston, K.L., Nakada, S.Y., Holmes, R.P. and Assimos, D.G., 2008. Quantitative assessment of citric acid in lemon juice, lime juice, and commercially-available fruit juice products. Journal of Endourology, 22(3), pp.567-570.
[5] Bhattacharjee, C., Saxena, V.K. and Dutta, S., 2017. Fruit juice processing using membrane technology: A review. Innovative Food Science & Emerging Technologies, 43, pp.136-153.