Pear juice

Bimessig, m. pear nnegar. bimfdrmig, a. pear-shaped, pyriform. Bim-most, m, pear juice, (new) perry. -61, n. 

Rodrfguez-Hernandez, G.R. et al.. Spray-drying of cactus pear juice (Opuntia strep-tacantha) effect on the physicochemical properties of powder and reconstituted product, Drying TechnoL, 23, 955, 2005. 

Hamdi, M., Blanc, P.J., and Goma, G., A new process for red pigment production by Monascus purpureus culture on prickly pear juice and the effect of partial oxygen pressure. Bioprocess Eng., 17, 75, 1995. 

Interest in arabinans has increased significantly in recent years due to their identification as a major cause of haze in apple and pear juice concentrates. These problems can be relieved by using pectic enzyme mixtures containing adequate levels of e do-arabinanase to degrade 1,5-a-L-arabinan produced from branched arabinan either by the action of a-L-arabinofuranosidase or a combination of heat and low pH conditions (23). 

In using this substrate to screen activity in a range of commercial pectinase preparations, it was found that for all preparations, except two, the same ratio of activity on this substrate and linear arabinan (from pear juice) was obtained as was obtained for pure em/o-arabinanase. One of these preparations was Novo Ultra SP. This preparation hydrolysed CM-Debranched Arabinan at 1.5 times the rate of pear-juice linear arabinan. This additional... 

Figure 2. Enzymic measurement of a-L-arabinan in fruit-juice concentrates, (a) Effect of time of incubation of sample with arabinofuranosidase and ndo-arabinanase. Diluted pear juice concentrate (1 10 0.1 ml) or sugar beet arabinan solution (0.1 ml) was incubated with an aliquot (0.1 ml) of arabinofuranosidase (5 units) plus ndo-arabinanase (0.2 units) at 35 C and pH 4.0. Aliquots were analysed for arabinose. (b) Arabinose determination using the NAD-Galactose Dehydrogenase method. Arabinose solution (0.2 ml, 50 digrams) was incubated with Tris-HCl buffer (2.5 ml, pH 8.6), NAD (0.1 ml, 10 m ml) and galactose dehydrogenase (20/i, 140 milliunits) at 35°C. Absorbance (340 nm) was measured after various time intervals.

Spanos, G.A. and Wrolstad, R.E., Influence of variety, maturity, processing and storage on the phenolic composition of pear juice, J. Agric. Food Chem., 38, 817, 1990. 

High-performance LC analysis of phenolics in apples and pear juices are often performed by gradient procedures (49-54), due to the presence of several phenolic classes. Most of the HPLC methods applied to apple phenolics are very similar to that of Oleszek et al. (55). 

Many different sample preparation procedures have been employed, ranging from simple filtration of juice products to solvent extraction, and extraction by SPE using C, 8, Sephadex LH-20 (49,50,52), and Amberlite XAD-2 (51,54,57). The Amberlite XAD-2 cleaning step has been used for many phenolic extracts, especially for fruit purees, to remove the sugars and other polar compounds. However, due to the low recovery rate with Amberlite XAD-2 for certain phenol glycosides, a modified sample preparation technique is needed, especially for quantification of ar-butin in pear juice and blends (54). Figure 6 describes the fractionation procedure for phenolics using a Sephadex LH-20 column (58). 

Junge, C. and Spandinger, C. (1982) Detection of the addition of L and D, L malic acids in apple and pear juice by quantitative determination of fiimaric acid . Flussiges Obst 49(2), 57-62. 

Campuzano et al. [29] Fructose Honey Pear juice Fructose dehydrogenase (FDH)/with glutaraldehyde Self-assembled monolayer (SAM) modified gold electrode/ +0.2 V vs. Ag/AgCl Tetrathiafiilvalene (TTF)/ with glutaraldehyde... 

An UF/OD integrated system has been used for the concentration of the cactus pear juice [28]. This juice is characterized by a high micro-organism load and it is typically clarified by thermal treatment (>110 °C) that significantly changes the original color, flavor, and taste. 

Clarification (apple juice, pear juice, grape musts or wines)... 

Ibarz, A., Vicente, M., and Graell, J. 1987. Rheological behavior of apple juice and pear juice and their concentrates.. 7 Food Eng. 6 257-267. 

Arthur s Fresh Company (arthursjuice.com)—A ai Plus contains purees of a ai berries, blackberries, blueberries, and boysenberries, apple and pear juices, and banana puree fortified with dietary fiber, antioxidant A-C-E vitamins, and nine other essential nutrients... 

The de-aromatised juice is either stored in sterilised condition (e.g. apple and pear juice) or concentrated. 

Ultrafiltration and microfiltrafion are employed successfully on an industrial scale for the clarification of juices (e.g. apple juice, pear juice, etc.). Ultrafiltration saves filter aids and fining aids which have to be used when operating conventionally with rotating vacuum filters or plate filters and precoat filters. On the other hand, the power consumption of an ultrafiltration system is high and so is the replacement cost of membranes. 

Figure 3. Unit operations for processing Bartlett, Comice, and D Anjou pear juice samples. (Reproduced from ref. 3. Copyright 1989 American Chemical Society.)...

Table I summarizes the results for the pear juice samples.

This HPLC procedure utilizes direct injection of juice samples on two reverse phase C-18 columns connected in series. Tartaric, quinic, malic, citric and fumaric acids were quantitated by the external standard method. Table II summarizes the results for the pear juice samples. Ripening had little influence on the total titratable acidity, however, quantitative differences in the compositional profile were evident. Most noticeably, the level of quinic acid was higher in the ripened fruit. 

Table I. Sugar Profile for Pear Juice Samples... 

Pear Phenolics. The same HPLC analytical system gave good resolution of pear juice phenolics and enabled peak assignments and quantitation to be made in a similar manner to that described for apple phenolics (3,7). It was also necessary to isolate the procyanidins and catechins using the Sephadex clean-up procedure (4) in order to measure their concentration. Figure 6A shows the HPLC separation of cinnamics, flavonols, and arbutin in pear juice while Figure 6B is a HPLC chromatogram of the pear juice procyanidin fraction. 

Figure 7. Effect of processing and storage on the phenolics of pear juice. Unit operations code P, pressed juice H, heat treatment E, enzyme clarification F, fined Ft, filtered B, bottled single-strength juice C, concentrate and CS, stored concentrate.

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