Changes in antioxidants and taste-related compounds content during cold storage of fresh-cut red sweet peppers

Changes in antioxidants (ascorbic acid, phenolic compounds and carotenoids) and in taste-related compounds (sugars and organic acids) content were monitored in fresh-cut red sweet peppers (Capsicum annuum L., local ecotype “Peperone Cornetto di Pontecorvo”) during 9 days of cold storage. Pepper slices were placed in polystyrene trays, wrapped with a polyvinyl chloride film, and stored at 4 °C or at 8 °C; besides, to evaluate the effect of a prestorage hot water treatment, half of the slices were subjected to a dipping treatment in water at 53 °C for 4 min, before packaging and storage. During storage limited changes in O₂ and CO₂ concentrations were observed within all packages. Storage temperature strongly affected weight loss: at the end of the storage time it was <3 and >10% in fruits stored at 4 and 8 °C, respectively. Sugars (glucose and fructose) content showed a significant increase (+11%) only in fruits stored at 8 °C; this change was due to a concentration effect associated to water loss. A higher increase (+23 and +17% in fruits stored at 8 and 4 °C) was observed in organic acids (citric and malic) content. Minimal processing and storage produced only a quite limited degradation of ascorbic acid. Both hydroxycinnamic acid derivatives and flavonoids accumulated in fruits stored at 8 °C (and not heat treated), whereas at 4 °C phenolics accumulation appeared to be partially inhibited. All the main carotenoids (capsanthin, cucurbitaxanthin A, zeaxanthin, β-carotene and β-cryptoxanthin) markedly accumulated in fruits stored at 8 °C (not heat treated), and showed a general decrease at 4 °C. Hot water treatment did seem to affect organic acids metabolism, though it did not promote ascorbic acid degradation. In addition, it inhibited both phenolics and carotenoid accumulation in fruits stored at 8 °C.     

Changes in the non-volatile organic acids of tomato fruit during ripening

A study has been made of the individual non-volatile organic acids in ethanolic extracts of tomato fruit during ripening. Whole fruit of three varieties and the outer walls and locular contents of one variety each at five stages of ripeness from mature green to full red were analysed. No trace of many of the K rebs-cycle acids could be detected. Maximum citric acid concentrations were found at either the green-yellow or yellow-orange stage of ripeness according to variety. Malic acid concentrations and the malic/citric acid ratio decreased progressively as the fruit ripened. Glutamic acid increased approximately ten-fold and aspartic acid more than doubled from the mature green to red stage of ripeness, but changes in pyrrolidonecarboxylic acid (PCA) during ripening were not statistically significant. In general, similar trends were observed in whole fruit and in the outer walls and locular contents, but malic, citric, glutamic and aspartic acid concentrations were higher in the locular contents than in the outer walls at all stages of ripeness. Alcohol-insoluble solids (AIS) decreased markedly between the green and green-yellow stages and then more slowly with further ripening.     

On the phenolic acids of vegetables. IV. Hydroxycinnamic acids and hydroxybenzoic acids of vegetables and potatoes (author's transl)]

Lettuce, endive and chicory exclusively, cornsalad and sweet fennel almost exclusively contain caffeic acid derivatives beside traces of ferulic acid. Parsley exclusively and spinach almost exclusively show p-coumaric acid derivatives. Compared to root, fruit and seed vegetables the contents of phenolic acids in green leaves are considerably high. Rhubarb is the only vegetable, which contains gallic acid (chief phenolic acid) beside hydroxycinnamic, protocatechuic and vanillic acid derivatives. Furthermore hydroxybenzoic acid derivatives (salicylic, gentisic and vanillic acid) occur in cornsalad, sweet fennel, parsley and spinach in small concentrations; cornsalad shows p-hydroxybenzoic acid (ca. 20 mg/kg). Onions (Allium cepa) contain almost only protocatechuic acid beside small amounts of p-hydroxybenzoic and vanillic acid. In the outer dry coloured skins protocatechuic acid reaches concentrations up to 2% of plant material; the internal pulpy tissues show lower concentrations (ca. 20 mg/kg). On the contrary to the bulbs the green leaves of onions like chive and leek contain almost exclusively compounds of ferulic and p-coumaric acid. Garlic even shows a different phenolic acid pattern of skins and internal tissues. The caffeic acid derivatives of potatoes are mainly localized to a 1--2 mm thick outer layer. The different localization of phenolic acids in the different parts of vegetable plants is discussed.     

Organic acids in vegetables. I. Brassica, leaf and bulb vegetables as well as carrots and celery

18 German vegetable species were analyzed for their organic acid content. Organic acids were isolated by methanol extraction followed by ion exchange. After derivatisation with BSA the trimethylsilyl derivatives were analyzed by gas chromatography using SE-52 and OV-1701 glass capillaries. The predominate acids are malic and citric acid, and in most cases malic acid was the most abundant. Succinic, fumaric, and quinic acids are wide spread, tartaric acid was found in carrots, lettuce, endives, chicory, and celery. Other acids such as malonic, shikimic, and t-aconitic acids occurred sporadically. Lactic acid which was determined by two other methods was not detected in any vegetable species.     

Changes in pH, acids, sugars and other quality parameters during extended vine holding of ripe processing tomatoes

BACKGROUND: Two important quality attributes of processing tomatoes are pH and titratable acidity. These and other quality attributes can be affected by tomato fruit maturity and over‐maturity. We have determined the magnitude of these maturity effects in four processing tomato cultivars commonly grown in California. RESULTS: Allowing tomatoes to remain on the vine for up to 4 weeks after ripening resulted in an increase in fruit pH of between 0.01 and 0.02 unit per day for the four cultivars examined. The increase in pH was paralleled by a decrease in titratable acidity, due to a loss of citric acid. Glucose and fructose concentrations also declined with increasing maturity after ripening. Other quality parameters (color, lycopene, total pectin, pectin solubility, and Bostwick consistency) all showed little change. CONCLUSION: Vine holding of ripe fruit adversely affects quality, especially pH and titratable acidity. Recent problems with high tomato juice pH encountered by tomato processors in California could be the result of increased average fruit maturity at harvest. Copyright © 2011 Society of Chemical Industry     

Changes in the components of dry-fermented sausages during ripening.

Several chemical changes occur during the ripening of dry-fermented sausages that determine the flavor and odor of the end product. The phenomena that take place during fermentation, that is, both acidification of the sugars by lactic acid bacteria and reduction of nitrates and nitrites to nitric oxide by micrococci have been known for several years. However, the chemical changes involved in this process, and, particularly, the agents responsible have not yet been established, although they have been attributed to changes in the majority components (proteins and lipids) and to the ingredients added (spices and condiments) in the preparation of the original mixture. The typical flavor and odor of dry-fermented sausages cannot be attributed to volatile substances alone, but to a large number of volatile and nonvolatile compounds present in the product in suitable proportions. Microbial growth in the sausage together with activity of the meat endogenous enzymes are undoubtedly partially responsible for the development of a number of aromatic and sapid compounds. However, lipid autooxidation reactions are also an important source of these substances, and it is not yet known which of these processes is more important in sausage ripening. Much research has focused on the break up of triglycerides into free fatty acids, diglycerides, and monoglycerides during ripening and the progressive increase in the amounts of different carbonyl oxidation products. Carbonyl compounds probably play a significant role in determining the flavor because, in general, these have very low perception thresholds, in the ppm and ppb range. Similarly, the protein breakdown to yield peptides and amino acids has been studied extensively, the latter being substrates of several microbial and chemical reactions that generate many flavor compounds.     

气相色谱—串联质谱结合固相萃取技术同时测定番茄和黄瓜中10种杀菌剂

建立了气相色谱—串联质谱(GC-MS/MS)测定蔬菜中啶氧菌酯、E-苯氧菌酯、醚菌酯等10种杀菌剂残留的检测方法。采用乙酸乙酯与环己烷的混合液对样品进行提取,优选出氨基固相萃取柱的净化方法,采用多反应监测(MRM)检测,外标法定量。结果表明,10种蔬菜杀菌剂药在15～500ng/mL的质量浓度范围内线性关系良好,相关系数均大于0.999 1,方法检出限为0.1～0.5μg/kg。实际样品加标回收率为84.7%～117.0%,相对标准偏差(n=6)为0.4%～4.7%,该方法适用于蔬菜中多种杀菌剂的同时检测。     

Changes in microbial populations, kinds of lactic acid bacteria and biochemical characteristics of Greek traditional feta cheese during ripening

Three batches of feta cheese manufactured from raw (R) and thermized (TS) milk with yogurt as a starter were studied. Enterobacteriaceae and coliforms underwent a more accelerated decrease in TS cheese. Nonstarter lactic acid bacteria (NSLAB) were counted at higher levels in R than in TS cheese throughout ripening and predominated over the other microbial groups. The composition of NSLAB in the fresh cheese was similar for both cheese types. Proteolysis products (noncasein nitrogen soluble in 12% trichloroacetic acid, nitrogen soluble in 5% phosphotungstic acid /100 total nitrogen) were higher in R than TS cheese. Degradation of αs-casein was in R > TS, while a small reduction of β-casein during storage was recorded only for TS cheese.     

Starch and sugar transformation during the ripening of plantains and bananas

Ripening changes were studied in plantains of three cultivars, two Horn types and one French type, and compared with those in bananas ripened under the same conditions. Bananas contained 1% starch when fully ripe and none when overripe, whereas plantains contained about 9% starch when fully ripe and 3% when overripe (composition expressed as percentage fresh weight). Total sugar content was 23% in fully ripe and overripe bananas but in plantains it increased from 20% when fully ripe to 27% when overripe. The ratio of glucose:fructose was approximately unity for bananas and plantains at all stages of ripeness. Sucrose comprised more than 70% of the total sugars in fully ripe bananas and plantains and about half of the total sugars in overripe fruits.     

重庆水豆豉发酵过程中NaCl、还原糖和氨基酸变化与滋味的形成

为探究重庆水豆豉独特滋味形成的影响因素,对水豆豉自然发酵过程中呈味物质变化与其滋味形成的关系进行了研究。以重庆本地大豆为原料,采用自然发酵工艺生产水豆豉,对其发酵过程中NaCl、还原糖、总酸、游离氨基酸等组成变化进行了测定,并对其感官评价结果进行了相关性分析。结果表明,水豆豉滋味主要形成于后发酵阶段,发酵结束时游离氨基酸含量增加了11. 25倍,其中鲜味氨基酸占比13. 45%,水豆豉鲜味主要来源于鲜味氨基酸;甜味氨基酸占比22. 25%,甜味氨基酸和还原糖共同构成了其略有回甜的滋味;咸味来源于NaCl质量分数增加;总酸增加形成一定的弱酸味。这些与添加的辣椒、姜等混合最终形成了重庆水豆豉独特的鲜咸酸辣略有回甜的滋味。研究结果对重庆地方调味品的滋味研究有一定意义。     

八种野菜氨基酸及维生素的含量分析

采用柱前衍生反相高效液相色谱法测定贵州8种野菜(鸭儿芹、蓝布正、鱼香菜、灰菜、剪刀菜、豆瓣菜、清明菜、水芹)中17种氨基酸含量,并采用高效液相色谱法测定了其中的维生素A、维生素E、维生素B1、维生素B2的含量。结果表明,在所测定的野菜中,豆瓣菜,灰菜、鱼香菜氨基酸总量和必需氨基酸含量较高;清明菜维生素A含量最高,鱼香菜、水芹、剪刀菜富含维生素E,蓝布正、豆瓣菜、清明菜富含维生素B1,豆瓣菜维生素B2含量最高。这些野菜具有较高的营养价值。      

Changes in flavour and texture during the ripening of strawberries

The amount of total volatile compounds, total acidity, total sugar content (degrees Brix) and fruit firmness were used to characterize the degree of ripeness of three strawberry varieties (Carezza, Darselect and Marmolada). A novel concept using solid phase microextraction (SPME) and measurement of total volatile compounds to distinguish between various stages of strawberry ripeness was applied. The carboxene/polydimethylsiloxane SPME fibre was found to be best suited to differentiate between the stages of ripeness. The amount of total volatile compounds rapidly increased near to maturity (between the three-quarters red stage and the dark-red stage). Most of the volatile compounds identified were esters, followed by aldehydes, and alcohols. The most abundant volatile compounds were propyl butanoate, 3-phenyl-1-propanol, butyl butanoate, isobutyl butanoate, 3-methyl butyl butanoate and isopropyl hexanoate. The concentration of green aroma components such as hexanal, trans-2-hexenol and cis-3-hexenyl acetate progressively decreased during the maturation process until they became minor components in mature strawberries.     

Changes in organic acids during ripening of cheeses made from raw, pasteurized or high-pressure-treated goats’ milk

Organic acids of cheeses made from raw (RA), pasteurized (PA; 72°C, 15 s) or pressure-treated (PR; 500 MPa, 15 min, 20°C) goats’ milk were qualitatively and quantitatively assessed during ripening. Nine organic acids (citric, pyruvic, malic, lactic, formic, acetic, uric, propionic and butyric) were analysed in each sample by HPLC.Milk treatment did not affect the total organic acids content of 1-day-old cheeses, which increased steadily from day 1 to day 60. At the end of ripening, RA and PR milk cheeses both exhibited higher concentration of organic acids than in those made from PA milk.Lactic acid was found in higher concentration in PR milk cheese from 30 days of ripening. The RA milk cheese, that showed the highest nonstarter lactic acid bacteria counts, were characterized by an elevated amount of propionic and acetic acids. These cheeses also were negatively correlated with both pyruvic and citric acid contents. The PA milk cheese showed a high level of malic acid, and was clearly differentiate from RA and PR milk cheeses by its low level of butyric acid.     

Changes in sugars, acids and fatty acids in naturally parthenocarpic date plum persimmon (Diospyros lotus L.) fruit during maturation and ripening

The date plum persimmon fruit (Diospyros lotus L., fam: Ebenaceae) is cultivated throughout northern of Turkey for its edible fruits. Sugars and organic acids were measured during fruit maturation and ripening using HPLC. The analyses showed that fructose and glucose were the main sugars accumulated in the fruit pulp. Fructose and glucose increased up to 43,552.8 mg.100 g^–1 fw and 35,450.8 mg.100 g^–1 fw respectively during fruit ripening. Sucrose content remained relatively low and decreased during ripening. The major organic acids found in date plum fruit were citric and malic acids, which increased through the immature and midripe maturity, and then the levels decreased in the overripe fruit. Palmitic acid (16:0), palmitoleic acid (16:1), stearic acid (18:0), oleic acid (18:1) and linolenic acid (18:3) were among the major fatty acids determined by GC throughout the maturation and ripening of the fruits. The levels of these fatty acids were found to be significantly different (P=0.05) between the three maturity stages. The fruits displayed the level of linoleic acid (0.7%) in low and -linolenic acid (17.8%) in higher quantities, and the combined levels of linoleic and -linolenic acid comprised 19% (120.1 g.g^–1 dw) of the total fatty acid content in the over ripened fruit. These results show that naturally parthenocarpic date plum fruits have high levels of sugars and organic acids and moderate levels of fatty acids that significantly changed during maturation and ripening. This information can be used by nutritionalists and food technologists to improve the nutrition of local people and develop food products that would be beneficial to human health.     

Changes in elements,pectic substances and organic acids during development of boysenberry fruit

Changes in elements, pectic fractions, and organic acids during the development of boysenberries are described. Fruit were grouped into nine developmental stages on the basis of fresh weight and anthocyanin content. Stages 1–5 covered the earliest period of development (Stage 1 fresh weight=1.34 g), marked by fruit expansion and little accumulation of anthocyanin, whereas during Stages 6–9, when ripening occurred, fruit expansion ceased and anthocyanin content increased greatly. Most elements (except B and Na) fell into two very distinct groups. Over the course of development the content of Ca, Mn and Sr per fruit varied bimodally and decreased after the cessation of fruit growth, indicating a net efflux from the fruit. In contrast, K, Mg, Fe, Cu, Zn, P and S, which were all very significantly intercorrelated (P<0.01), increased approximately linearly and thus showed a net influx into the fruit. The decrease in Ca, Mn and Sr content per fruit coincided with a decrease in Ca pectate and total pectin, and a greatly increased proportion of cold water-soluble pectin. Three acids, citric, malic and succinic, were detectable, with citric acid predominant. The changing content of malic acid paralleled that of Ca. The observed patterns of change suggested an increasing phloem/xylem influx ratio during fruit enlargement, with a subsequent loss of binding capacity in the cell-wall, enabling remobilization of wall-bound elements. The results imply that the Ca level in the fruit is important in the ripening of bramble fruit.     

Antifungal effectiveness of potassium sorbate incorporated in edible coatings against spoilage molds of apples, cucumbers, and tomatoes during refrigerated storage

Abstract: Predominant spoilage molds of fresh apples, cucumbers, and tomatoes stored at 4 °C were isolated and examined for resistance to potassium sorbate (PS) incorporated in polysaccharide edible coatings. The isolated molds were Penicillium expansum, Cladosporium herbarum, and Aspergillus niger from apples. P. oxalicum and C. cucumerinum were isolated from cucumbers and P. expansium and C. fulvum from tomatoes. Guar gum edible coating incorporated with PS was the most effective mold inhibitor, significantly (P < 0.05) reducing the isolated spoilage molds for 20, 15, and 20 d of storage at 4 °C on apples, cucumbers, and tomatoes, respectively. PS incorporated into pea starch edible coating was less effective and selectively inhibited the isolated mold species, causing significant (P < 0.05) reduction in mold on apples, cucumbers, and tomatoes counts for 20, 10 to 15, and 15 to 20 d of storage at 4 °C, respectively. The isolated mold species exhibited different resistances to PS incorporated in the edible coatings. The greatest inhibition (2.9 log CFU/g) was obtained with C. herbarum on apples and the smallest (1.1 log CFU/g) was with P. oxalicum on cucumbers and the other isolated mold species exhibited intermediate resistance. The coatings tested, in general, inhibited molds more effectively on apples than on tomatoes and cucumbers. Addition of PS to pea starch and guar gum, edible coatings improved the antifungal activity of PS against isolated spoilage molds on apples, cucumbers, and tomatoes. PS inhibition was most effective against C. herbarum on apples and least effective against P. oxalicum on cucumbers.     

Changes in ethylene and CO2 during the ripening of apples

The internal concentrations and production of both ethylene and CO₂ were measured during the maturation and ripening of Cox's Orange Pippin apples. Within 12 hours of the onset of the respiration climacteric there was no measurable increase in the production of ethylene and the data indicate that the increase in ethylene production is synchronous with the increased CO₂ production that marks the start of ripening. It therefore appears that a factor other than a change in the rate of ethylene production determines the time at which apples commence ripening.     

Changes in the individual sugars of tomato fruit during ripening

Changes in the concentrations of the individual sugars of the walls and locular contents of tomato fruit during ripening have been studied. The major sugars were glucose and fructose together with much smaller amounts of sucrose and myoinositol. During the initial stages of development the fruit contained approximately twice as much glucose as fructose, but with approaching maturity and the onset of ripening the glucose/fructose ratio declined to less than unity. On a per fruit basis the distribution of the major sugars between the walls and locular contents was about 3 : 1 at the green stage, falling to 2 : 1 as the fruit ripened. Total reducing sugars (% fresh weight or per fruit) increased markedly between the mature green and green-yellow stages with a tendency to decrease with subsequent ripening. These changes were predominantly influenced by changes in fructose content, with glucose changing little. The concentrations of sucrose and myoinositol, both less than 0.05% fresh weight, declined with ripening. The green areas of the outer walls of “blotchy” fruit contained much less glucose and fructose than did the walls of normal mature green fruit, while the red areas contained amounts similar to those encountered in normally ripened red fruit.