Pineapple juice, acid concentrations

Furthermore, the same authors also showed that at any concentration used in their experiments, the driving force reduction due to the concentration polarisation effect was higher than that of the temperature polarisation effect. For example, at 8 mol/kg, CaCl2 corresponds to 225 Pa of reduction in driving force due to concentration polarisation, whereas the reduction due to temperature polarisation effect is only 75 Pa. The best result obtained by Ravindra Babu et al. (2008) in terms of pineapple juice concentration was up to 62° Brix, preserving the ascorbic acid content of the fruit. 

In the pineapple industry, the fruit hulls are pressed for their juice content and the residue dried for use as a feed supplement. The clarified pineapple mill juice, obtained from pineapple hulls and other waste portions of the fruit, is decolorized after liming and filtration to recover calcium citrate. The demineralized syrup produces a sugar solution which when concentrated may be used as a syrup for sweetening sliced pineapple or as sugar syrup for use in fruit canning operations. Apple juice expressed from peels, cores, and hulls has been deionized to produce bland apple syrup. Ion exchange produced a stable apple syrup from which was removed not only a major portion of the fruit ash but also some of the introduced insecticides. Apple juice, on demineralization and subsequent concentration by evaporation, yields heavy syrup which has fine humectant properties. In apple juice demineralization, the malic acid in the juice was concentrated on an anion-exchange resin [160]. 

Several bioactive compounds have been reported for pineapple fruit and juice, including the phenolic compounds p-coumaric, caflfeic, fer-rulic, and p-hydrobenzoic acids as well as vitamin C and carotenoids (Simon et al. 1992 Gardner et al. 2000). More recently, nine major phenolic compoimds were characterized and quantified in 54 commercial samples of pineapple juice concentrate samples— tyrosine, serotonin, di-metiiylhydroxylfuianone, dimethylhydroxylfiiranone b-glucoside, tryptophan, -sinapyl-L-cysteine, iV-g-L-glutamyl-5 -sinapyl-L-cysteine, S-sinapyl glutathione, and p-coumaric acid (Wen and Wrolstad 2002). 

Another example of an MCFIA system is shown in Figure 4.6. This MCFIA system was designed to implement an automated titration procedure [36]. The system was applied to samples with a wide range of acid concentration such as vinegar and lemon, orange, pineapple, maracock, and acajou juices. 

Acetic acid occurs naturally in many plant species including Merrill flowers Telosma cordata), in which it was detected at a concentration of 2,610 ppm (Furukawa et al., 1993). In addition, acetic acid was detected in cacao seeds (1,520 to 7,100 ppm), celery, blackwood, blueberry juice (0.7 ppm), pineapples, licorice roots (2 ppm), grapes (1,500 to 2,000 ppm), onion bulbs, oats, horse chestnuts, coriander, ginseng, hot peppers, linseed (3,105 to 3,853 ppm), ambrette, and chocolate vines (Duke, 1992). 

Ingredients Carbonated water. Concentrated fruit juices (pineapple, grapefruit) (5% when reconstituted). Citric acid. Acidity regulator (sodium citrate). Artificial sweeteners (aspartame, saccharin). Flavourings. Preservative (sodium benzoate). Antioxidants (ascorbic acid, ascorbyl palmitate). Colour (lutein)... 

The concentration of most fruit juices is conveniently measured in degrees Brix, although the strict interpretation of this measure refers to pure solutions of sucrose in water (e.g. 10°Brix is 10% w/w sucrose in water). For juices with a high proportion of sugars to acids, such as orange, pineapple and apple, this is... 

Citric acid occurs naturally in a number of plant species and may be extracted from lemon juice, which contains 5-8% citric acid, or pineapple waste. Anhydrous citric acid may also be produced industrially by mycological fermentation of crude sugar solutions such as molasses, using strains of Aspergillus niger. Citric acid is purified by recrystallization the anhydrous form is obtained from a hot concentrated aqueous solution and the monohydrate from a cold concentrated aqueous solution. 

---