Lemon juice concentrates

Table V. Properties of Feed, Concentrate (Cone) and Permeate (Perm) Streams for Orange, Grapefruit and Lemon Juices Concentrated by Reverse Osmosis...

Frozen lemon juice concentrate has four times the caloric and nutrient levels of bottled, canned, or fresh lemon juice. Hence, it may make a significant nutritional contribution when added undiluted to drinks, salad dressings, and sauces. However, additional caloric or noncaloric sweetener may be needed because the pure juice concentrate is very tart. 

Frozen lemonade concentrate contains considerable added sweetener and is 58% higher in calories (it contains 195 kcal per 100 g [3 1/2 oz]) than unsweetened frozen lemon juice concentrate. Furthermore, the lemonade concentrate contains much lower levels of potassium and vitamin C. 

Lemon and Lime Juice. Lemons and Persian limes can be extracted using the same PMC and AMC extractors described above. The juice can be concentrated in a TASTE evaporator, an APV Crepaco, Inc. evaporator, or other types of evaporators (13). Although lime juice, and especially lemon juice, are widely used as condiments on food, the bulk of concentrated juice is used to make frozen concentrated lemonade and limeade. Prozen... 

FICURE10.il A pH meter is a voltmeter that measures the pH electrochemically. The two samples are (a) orange juice and (b) lemon juice. Notice that the lemon juice has a lower pH and hence a higher concentration of hydronium ions. 

Because hydronium concentrations usually involve negative powers of ten, chemists use a negative log scale in expressing these concentrations. Equation defines the pH scale of acid concentration pH = - log [H3 O ] The pH of a solution is obtained by taking the logarithm of the hydronium ion concentration and then changing the sign. For example, the pH of pure water is pH = - log [H3 O ] = - log (1.0 X 10 ) — -(-7.00) — 7.00 The reverse conversion from pH to [H3 O ] uses powers of 10. For example, lemon juice has a pH of about 2.0 ... 

A glass of lemon juice was found to have a pH of 3 and a glass of apple juice a pH of 5. From this information, the concentration of hydrogen ions in the lemon juice and apple juice are in the proportion (ratio)... 

Lemon peel oil is much more valuable than its juice therefore, extensive research efforts have been expended to determine its natural composition as a way to detect adulteration as well as to determine quality factors [6, 31, 32]. However, a few studies on lemon juice volatiles can be found [33-35]. Lemon oils are notable for possessing relatively low levels of limonene (more than 70%) and relatively high levels of a-pinene (1-2%), -pinene (6-13%), sabinene (1-2%) and y-terpinene (8-10%) [32]. The relatively high concentration of -pinene is thought to instil the green peely odour of lemon oil. The concentrations of aliphatic and monoterpenic aldehydes, (especially citral) as well as those of esters and alcohols are critical components in the perceived quality of the oil. As lemon oil is unstable, quality can deteriorate with improper storage, resulting in... 

In 1795 the British admiralty finally mandated a ration of concentrated lime or lemon juice for all British sailors (hence the name limeys ). Scurvy continued to be a problem in some other parts of the world until 1932, when Hungarian scientist Albert Szent-Gyorgyi, and W. A. Waugh and C. G. King at the University of Pittsburgh, isolated and synthesized ascorbic acid. 

Figure 6-7 pH of various substances. [From Chem. Eng. News. 14 September 1981.] The most acidic rainfall (Box 15-1) is a stronger acid than lemon juice. The most acidic natural waters known are mine waters, with total dissolved metal concentrations of 200 g/L and sulfate concentrations of 760 g/L The pH of this water, -3.6, does not mean that [H ] = 103- M ... 

Refractometer readings can be affected by the presence of other dissolved solids. The presence of fruit acids in particular can influence the refractometric Brix reading and should strictly be taken into account when calculating juice concentration. In most cases the effect is not significant however, when there are appreciable levels of acid in the juice, for example, lemon and lime juices, there will be a need to apply the collection. 

The concentration of H30+ ions in a sample of lemon juice is 2.5 X 10 3 M. Calculate the concentration of OH- ions, and classify the solution as acidic, neutral, or basic. 

If you use a calculator to find the pH from the H30+ concentration, your answer will have more decimal places than the proper number of significant figures. For example, the pH of the lemon juice in Worked Example 15.4 ([H30+] = 2.5 X 10 3 M) is found on a calculator to be... 

The acidity of lemon juice is derived primarily from citric acid (H3Cit), a triprotic acid. What are the concentrations of H3Cit, H2Cit-, HCit2-, and Cit3- in a sample of lemon juice that has a pH of 2.37 and a total concentration of the four citrate-containing species of 0.350 M ... 

Lemon juice has many uses in the food industry that other juices do not have because of its uniquely different composition in relation to other juices, except perhaps lime. Large quantities of lemon juice are used to enhance food flavors and to develop and balance the flavors of many food items, seafood being an outstanding example. Possibly only sugar and salt are used more extensively in the development and enhancement of food flavors. Lemon juice has also gained in popularity because of technological advances that now permit the manufacture of concentrated juices and the production of a frozen concentrate for lemonade. 

Sn+, Fe+3, Sn+, and Al+. These investigators reported that 3-deoxyglucosone and 5-hydroxymethylfurfural were intermediates in the browning of concentrated lemon juice that occurred when the concentrate was diluted to single-strength juice with a sucrose solution. They concluded that amino acids had a role in the browning (51). 

The acid in concentrated lemon juice for manufacture is expressed as grams per liter. The easiest way to determine the acid in this product is to determine the acid in grams per 100 grams and convert this to grams per liter, e.g. 

What results would you expect if you tried cleaning a penny in a solution of lemon juice What if you used a dilute solution of ammonia Note If you want to test your predictions, ask your teacher for the concentrations of the solutions you should use. 

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