Citrus fruits. Part II. Chemistry,technology, and quality evaluation. C. quality evaluation

In Part II of this review on citrus fruits, the literature on chemistry, technology, and quality evaluation are critically considered. Sweet oranges, mandarin, grapefruit, lemon and lime are generally used for processing. The literature on chemical components of citrus fruits reviewed and discussed in Section A includes the following: sugars, polysaccharides, organic acids, nitrogenous constituents, and lipids; carotenoids which contribute to color; vitamins and minerals, and flavonoids; limonoids, some of which impart bitterness to the juice, and the volatile components which contribute to aroma. Chilled and pasteurized juices, juice concentrates, and beverages are the important products manufactured commercially, and to a limited extent powdered citrus juices, canned segments, and marmalades. The literature on the manufacture of these products as well as new types of juice and oil extractors, TASTE, and other types of evaporators, tank farms to store juice and concentrate in bulk, aseptic filling in bulk containers and retail packs, alternate flexible and rigid containers other than glass and tin and recovery of volatile flavoring constituents during juice processing are some of the important technological developments in the recent past which were discussed in Section B. Bitterness in citrus juices and its control, composition of cloud and its stability, and changes during storage have been reviewed. Essential oils, pectin, frozen and dried juice sacs, dried pulp and molasses, flavonoids, seed oil, and meal are the important by‐products, the manufacture of which is given in essential details. Generally, consumers judge the product on the basis of its sensory attributes. The quality of the finished products is dependent upon the raw materials used and control of processes. In this section, the USDA standards for different products, physico‐chemical and microbiological parameters prescribed as indices of quality of fruit, juice, concentrate, and other products, composition of essential oils, and aroma concentrates are discussed in relation to sensory quality. Analytical methods for compounds affecting quality and methods for detection of adulteration in different citrus products are briefly reviewed. The importance of sensorily evaluating quality of citrus products to select and develop quality control indices is emphasized. Areas where further research is required are indicated. A comprehensive bibliography is provided to aid further study and research.     

Citrus fruits. Part II. Chemistry, technology, and quality evaluation. B. Technology

In Part II of this review on citrus fruits, the literature on chemistry, technology, and quality evaluation are critically considered. Sweet oranges, mandarin, grapefruit, lemon, and lime are generally used for processing. The literature on chemical components of citrus fruit which include sugars, polysaccharides, organic acids, nitrogenous constituents and lipids; carotenoids which contribute to color; vitamins and minerals and flavonoids; limonoids, some of which impart bitterness to the juice; and the volatile components which contribute to aroma were reviewed in section A. Chilled and pasteurized juices, juice concentrates, and beverages are the important products manufactured commercially, and to a limited extent powdered citrus juices, canned segments, and marmalades. The literature on the manufacture of these products also as new types of juice and oil extractors; TASTE and other types of evaporators; tank farms to store juice and concentrate in bulk; aseptic filling in bulk containers and retail packs; alternate flexible and rigid containers other than glass and tin; and recovery of volatile flavoring constituents during juice processing are some of the important technological developments in the recent past and have been discussed in this section. Bitterness in citrus juices and its control, composition of cloud, and its stability and changes during storage have been reviewed. Essential oils, pectin, frozen and dried juice sacs, dried pulp and molasses, flavonoids, seed oil, and meal are the important byproducts, the manufacture of which is given in essential details. Generally, consumers judge the product on the basis of its sensory attributes. The quality of finished product is dependent upon the raw materials used and control of processes. In section C, the U.S. Department of Agriculture (USDA) standards for different products, physicochemical and microbiological parameters prescribed as indices of quality of fruit, juice, concentrate, and other products; composition of essential oils; and aroma concentrates are discussed in relation to sensory quality. Analytical methods for compounds affecting quality, and methods for detection of adulteration in different citrus products are briefly reviewed. The importance of sensorily evaluating quality of citrus products to select and develop quality control indices is emphasized. Areas where further research are required are indicated. A comprehensive bibliography is provided to aid further study and research.     

Limonene, linalool, α-terpineol, and terpinen-4-ol as quality control parameters in mandarin juice processing

Consumers demand commercial citrus juices resembling fresh juices; however, citrus juice elaboration is quite delicate due to the formation of off-flavors during heat treatment and storage. Four volatile compounds, d-limonene, linalool, α-terpineol, and terpinen-4-ol were extracted using the dynamic headspace technique and were identified and quantified by GC-MS in mandarin juices from two Spanish varieties, Fortuna and Clemenules. Our results clearly demonstrated that both the pasteurization and storage steps significantly affected concentrations of these four aroma compounds. Formation of off-flavors components, α-terpineol and terpinen-4-ol, and simultaneous decomposition of d-limonene and linalool were observed in mandarin juices. Therefore, measurements of the stability of d-limonene and linalool, and formation of α-terpineol and terpinen-4-ol will help mandarin juice producers in analyzing the quality of their products.     

Modulation of aroma and flavor using glow discharge plasma technology

This study evaluates the use of cold plasma technology to induce flavor and aroma modifications and improvement of sensory quality in juices and fruit pulps. The work investigated the changes induced by glow discharge plasma processing on the volatile compounds and flavor profile of fruit pulps, using camu-camu as a case study. Camu-camu pulp was subjected to glow discharge plasma operating at different processing times (10 to 30 min) and synthetic air plasma flowrates (10 to 30 mL/min). The headspace compounds were identified and quantified using GC–MS analysis, and consisted mainly of terpenoids, sesquiterpenoids, and alcohols. Cold plasma application induced a series of chemical modifications in the volatile compounds. The chemical pathway of the reactions induced by plasma application was proposed and discussed. The changes in the composition of the volatile compounds varied with the operating conditions, and induced changes in the aroma and flavor of the juice. Depending on the operating condition, modulation of aroma and flavor was possible increasing or decreasing, up to a certain level, the woody (34.2%), herbal (29.1%), terpenic (47.3%), spicy (18.2%), citrus (28.7%), and camphoraceous (81.9%) notes of the juice. The results presented in this work open the possibility of flavor and aroma modifications and improvement of sensory quality in food products, using plasma technology.     

Athermal concentration by osmotic evaporation of roselle extract, apple and grape juices and impact on quality

Osmotic evaporation (or osmotic distillation) was carried out on roselle extract, apple and grape juices. The industrial pilot plant used had a hydrophobic, polypropylene, hollow-fiber membrane with an area of 10.2 m² and an average pore diameter of 0.2 μm. It was suitable for concentrating vegetable extracts and fruit juices, and controlled various parameters such as temperature, flow velocity, and brine concentration. The final total soluble solids (TSS) contents achieved were 660, 570, and 610 g kg⁻¹ for grape juice, apple juice, and roselle extract, respectively. Temperature and concentration of solutions significantly influenced evaporation flux, which, for roselle extract, was 1.5 kg h⁻¹ m⁻² at 610 g TSS kg⁻¹ and 45 °C. The physico-chemical, biochemical, and aromatic qualities of concentrates obtained by osmotic evaporation were much higher than those of thermal concentrates, and close to those of the initial products.

Industrial relevance

Membrane processes are increasingly used to concentrate thermo-sensitive fruit juices and plant extracts. Their capacity to operate at moderate temperatures and pressures means that their energy consumption is low, while they produce good quality concentrates. Nonetheless, the main disadvantage of baromembrane processes is their inability to reach the concentration levels standard for products of thermal evaporation because of limitations resulting from high osmotic pressure. Actually, reverse osmosis membranes and equipment limit the final concentration of fruit juices to about 25–35°Brix. Osmotic evaporation has attracted considerable interest, as it can concentrate juices to as much as 65°Brix. This process, when applied to various juices, better preserves the quality of raw materials. However, because of the geometrical limitations of commercially available membranes and modules, juices must first be clarified. To our knowledge, only a few studies on osmotic evaporation have so far been conducted at a semi-industrial scale and never with roselle extracts.     

酶技术在果蔬汁加工业中的应用

酶技术将成为果蔬汁加工业中的主要生物技术。利用各种酶可以改变果蔬汁中的质构和营养价值以提高其产品质量。文章对酶技术在柑桔类果汁、胡萝卜汁、荔枝汁加工业中的应用以及酶法促进果蔬汁的香气与风味、酶法免疫检测方面的应用作一综合介绍。     

Composition of Some Organic and Inorganic Compounds in Reverse Osmosis-Concentrated Citrus Juices

Orange, grapefruit and lemon juices were concentrated over twofold in a pilot scale reverse osmosis (RO) process using a commercially available membrane system. Major sugars, acids, vitamin C, aroma volatiles and over 20 minerals were examined in feed, concentrate and permeate streams. Typically, 15–20 aroma compounds were identified in feed juices and concentrates. Compared with less volatile compounds (e.g., ethyl butyrate, limonene), poorer retention during processing was noted for more volatile molecules (methanol, acetaldehyde, ethanol). °Brix of membrane concentrates were orange (25.3°B), grapefruit (25.1°B) and lemon (22.5°B). Vitamin C was rejected efficiently by the membrane. Mineral analyses showed similar elemental contents in feed and concentrate and insignificant concentration in permeate streams.     

The quality of orange juice processed by coupling crossflow microfiltration and osmotic evaporation

Crossflow microfiltration (CFM) and osmotic evaporation (OE) were implemented on a semi‐industrial pilot scale to obtain clarified orange juice concentrates at 450 and 620 g kg^?1 of total soluble solids. The characteristics of the juice were then assessed and compared with fresh juice and commercial concentrates. With CFM, most aroma compounds and vitamin C remained in the permeate while the more apolar compounds such as terpenic hydrocarbons and carotenoids were strongly retained by the membrane. With OE, significant losses of vitamin C and aroma compounds occurred at first, with losses progressively decreasing during treatment. Pre‐conditioning the membrane and cold regeneration of the brine reduced losses drastically, with the aroma composition tending towards that of the initial juice. The quality of pulp, a blend of the CFM retentate and OE concentrate, was high and much closer to that of the initial fresh juice than to the commercial thermal concentrate.     

Development of a headspace trap HRGC/MS method for the assessment of the relevance of certain aroma compounds on the sensorial characteristics of commercial apple juice

A reliable and simple method was developed for the completely automatised analysis of apple juice aroma compounds. In total 26 flavour compounds could be measured by headspace trap gas chromatography/mass spectrometry (GC/MS). We used the method to analyse 85 commercially available apple juices, of which 67 apple juices were not from concentrate. Our results show that apple juices not from concentrate are mainly characterised by flavour compounds responsible for fruity, ripe, and sweet aroma impressions, such as 1-butanol, 2-methyl-1-butanol, ethylbutyrate, and ethyl-2-methylbutyrate. On the contrary, apple juices made from concentrate were dominated by acetaldehyde, E-2-hexenal, 3-methyl-1-butanol, ethyl acetate, and hexanal, which are mainly responsible for sensory impressions, such as ‘green, fresh, estery’. According to our data, neither of the single compounds nor indexes calculated thereof as suggested by some authors could be used for the reliable assessment of apple juice quality. Thus, these results suggest that sensory evaluation remains the ultimate mean to reliably assess apple juice quality.     

Ginger-chemistry, technology, and quality evaluation: part 2

Ginger is used in more ways than any other spice. This monograph, published in two parts, comprehensively reviews production, trade, processing, chemistry, and evaluation of quality. Botany, world varieties, agronomy, crop improvement, and potential are reviewed briefly with emphasis on the yield of functional components. Processing for the market, international trade patterns and factors influencing them are discussed. Derived products such as ginger powder, syruped ginger, volatile oil, and oleoresin are discussed in greater detail. The increasing world demand for quality products of added value such as the oleoresin and volatile oil show the prospects for their production in the growing countries. The chemistry of the components which contribute aroma and pungency that characterize ginger is critically reviewed. The second part deals with evaluation of quality. The physicochemical parameters prescribed as a measure of quality for ginger and its products in the existing standards, can assure only hygienic quality and purity, and possibly the source, when new parameters such as GC-finger prints are included. The importance of sensorily evaluating flavor quality is emphasized to understand the variation in flavor quality required by the industrial and retail markets. Related areas, such as problems in sensory evaluation of intense flavored substances, objective flavor profile analysis, correlation of instrumental and sensory data are discussed, and our recent work in this area is summarized. Areas where more research is needed are indicated. Other areas briefly discussed are functional, physiological, and toxicological properties in use of ginger; biosynthetic aspects of components stimulating flavor; structure and pungency and chemistry of spices from allied species and genera. A comprehensive bibliography is provided to aid in further study and research.     

5-hydroxymethylfurfural as indicator of quality of juices for child nutrition

132 samples of domestic and imported juices and juice concentrates for child nutrition were analyzed on content of 5-hydroxymethylfurfurol (5-HMF), which is considered as an indicator of violation of juice manufacturing technology. The concentrations of 5-HMF in 15.9% of domestic juice samples and 10.3% of imported juice and concentrate samples were found higher than 20 mg/L--maximum level established by AIJN for some juices and nectars. The results confirmed the expediency of including of HMF maximum concentration in hygienic characterization of fruit juices and concentrates as an indicator of violation of their manufacturing and storage procedures.     

酶技术在果蔬汁加工业中的应用

酶技术将成为果蔬汁加工业中的主要生物技术。利用各种酶可以改变果蔬汁中的质构和营养价值以提高其产品质量。文章对酶技术在柑桔类果汁、胡萝卜汁、荔枝汁加工业中的应用以及酶法促进果蔬汁的香气与风味、酶法免疫检测方面的应用作一综合介绍。     

Orange juice quality with an emphasis on flavor components

This review studies the chemistry of the flavor of citrus juices with emphasis on the components of the flavor of orange juice and their origin in the different parts of the orange fruit. Citrus processing and the nature of the various products as they affect flavor are discussed. The composition of peel oil, aroma oil, orange juice, orange essence, and orange essence oil is presented. The relationship between flavor and color are discussed and the role of lipid components as they affect flavor stability and off‐flavors are described. Spoilage resulting from microbes is briefly treated. The nutritional value of orange juice is cited.     

Ginger — chemistry,technology, and quality evaluation: Part 2

Ginger is used in more ways than any other spice. This monograph, published in two parts, comprehensively reviews production, trade, processing, chemistry, and evaluation of quality. Botany, world varieties, agronomy, crop improvement, and potential are reviewed briefly with emphasis on the yield of functional components. Processing for the market, international trade patterns and factors influencing them are discussed. Derived products such as ginger powder, syruped ginger, volatile oil, and oleoresin are discussed in greater detail. The increasing world demand for quality products of added value such as the oleoresin and volatile oil show the prospects for their production in the growing countries. The chemistry of the components which contribute aroma and pungency that characterize ginger is critically reviewed. The second part deals with evaluation of quality. The physicochemical parameters prescribed as a measure of quality for ginger and its products in the existing standards, can assure only hygienic quality and purity, and possibly the source, when new parameters such as GC‐finger prints are included. The importance of sensorily evaluating flavor quality is emphasized to understand the variation in flavor quality required by the industrial and retail markets. Related areas, such as problems in sensory evaluation of intense flavored substances, objective flavor profile analysis, correlation of instrumental and sensory data are discussed, and our recent work in this area is summarized. Areas where more research is needed are indicated. Other areas briefly discussed are functional, physiological, and toxicological properties in use of ginger; biosynthetic aspects of the components stimulating flavor, structure and pungency and chemistry of spices from allied species and genera. A comprehensive bibliography is provided to aid in further study and research.     

PINEAPPLE JUICE CONCENTRATED BY OSMOTIC EVAPORATION1

Pasteurized pineapple juice was concentrated by osmotic evaporation to produce a 51 d?Brix concentrate that was reconstituted to single strength juice for evaluation. Headspace gas chromatography (HSGC) showed that the concentrate retained an average of 62% of the volatile components present in the initial juice. A sensory panel preferred initial juice over reconstituted concentrate, and noted a decrease in desirable flavor top notes as well as development of some processed flavor in the concentrate. Similar HSGC analysis of four other commercial juice samples showed a wide range of quantitative values for volatile components, with the initial juice being similar to the weakest of these commercial juices. Analysis of concentrated juice extracts permitted identification of additional less‐volatile components not monitored directly by HSGC of the juice. Relatively low levels of these components were also present in the initial juice. Although this nonthermally produced concentrate retains more volatile components than when traditional thermal processing methods are used, addition of aqueous aroma to the concentrate may be required for satisfactory flavor.     

柑橘属药食同源植物次生代谢物及生物活性研究进展

柑橘属植物是重要的药食同源植物。枳壳、枳实、佛手、枳雀、化橘红和广陈皮是常见的柑橘属药食同源植物制品,含有丰富的类黄酮、香豆素、生物碱、类柠檬苦素和挥发油等活性成分,具有抗氧化、抗炎、降血脂、抗抑郁和止咳化痰等多种生物活性,被广泛应用于保健品、食品和医药等领域中。这6 种药食同源制品均源自柑橘属植物果实,但各自活性成分组成存在差异,临床功效也不同,目前尚缺乏系统的归纳和比较。本文系统地比较了它们的活性成分和生物活性,以期为柑橘属植物资源的进一步研究与合理利用提供理论依据。     

SPME-GC-MS测定葡萄原汁中的挥发性物质

葡萄原汁中的挥发性成分直接影响葡萄制品的感官质量.采用SPME-GC-MS(固相微萃取-气相色谱-质谱)对山葡萄和欧亚种葡萄原汁中的挥发性风味成分进行分析,共鉴定出65种风味物质,可分为酯、烯、醛、醇、酮、烷、呋喃、苯环、杂环等9大类.与欧亚种葡萄相比,山葡萄原汁中风味物质的种类和含量较多.从葡萄汁的风味体系上分析,山葡萄原汁中醛、醇、烯的组成较高;欧亚种葡萄原汁中酯、醛的组成较高.     

Pulsed Electric Field Processing of Orange Juice: A Review on Microbial,Enzymatic, Nutritional,and Sensory Quality and Stability

During the last decades pulsed electric field (PEF) processing received considerable attention due to its potential to enhance food products or create alternatives to conventional methods in food processing. It is generally acknowledged that PEF processing can deliver safe and chill‐stable fruit juices with fresh‐like sensory and nutritional properties. Relatively low‐processing temperature and short residence times can achieve highly effective inactivation of microorganisms while retaining product quality. A first commercial application of PEF for preservation of fruit juices was launched in 2006 in the United States. Since then, industrial‐scale processing equipment for liquid and solid products were developed and, in Europe in 2009, an industrial juice preservation line was installed using 20 kV/cm pulses at 40 to 50 °C to extend the chill‐stability of fruit juices, including citrus juices and smoothies, from 6 to 21 d. The related PEF processing costs are in the range of US $0.02 to 0.03 per liter and are justified due to access to new markets and reduced return of spoiled product. However, despite its commercial success there are still many unknown factors associated with PEF processing of fruit and citrus juices and many conflicting reports in the literature. This literature review, therefore, aims to provide a comprehensive overview of the current scientific knowledge of PEF effects on microbial, enzymatic, nutritional, and sensory quality and stability of orange juices.     

Effects of organic farming on minerals contents and aroma composition of Clemenules mandarin juice

Consumers demand organic products because they believe that the organic products are more flavorful and respectful to the environment and human health. The effects of organic farming on the minerals contents and aroma composition of Clemenules mandarin juices were studied. Minerals (Fe, Cu, Mn, Zn, Ca, Mg, K, and Na) were quantified using atomic absorption-emission spectroscopy, while volatile compounds were extracted using the dynamic headspace technique and were identified and quantified by GC–MS. In general, organic farming produced a mandarin juice with a higher quality than that produced by conventional agricultural practices. Higher concentrations of both minerals and positive volatile compounds were found in the organic juice, while the formation of off-flavors was higher in the conventional juice, although threshold values were not reached.     

Improving the quality of some Egyptian fermented dairy products made from dried milk

A trial has been made to improve the quality of Zabadi and Kariesh cheese made from dried milk using whey protein concentrates. Fortification of recombined milk used for Zabadi making or reconstituted milk for Kariesh cheese manufacture with whey protein concentrates at levels of 2.5, 5.0, 7.5 and 10.0% enhanced the organoleptic and compositional qualities of both products. This treatment reduced wheying off and stimulated the formation of acetaldehyde and total volatile acidity and bacterial growth during storage of Zabadi at refrigeration temperature for one week.