Microbial content of commercial South African high-moisture dried fruits

AIM: The aim was to evaluate commercially available South African high-moisture dried fruits (HMDF) for the microbial, moisture and SO2 contents, as well as aw and pH. METHODS AND RESULTS: The microbial content of commercially available HMDF was evaluated using nine different growth media. The moisture content, aw) SO2 and pH of each product were determined using standard analytical methods. It was found that the highest total aerobic counts were generated from high-moisture dried (HMD) prunes and raisins. The most frequent spoilers were members of the genus Bacillus. Fungal counts were also very high in the apricot products, exceeding the limit of 1000 CFU g(-1) as set by HMDF producers. Members of the genus Staphylococcus were found in the HMD raisins and Salmonella and thermoduric organisms were isolated from the HMD prunes. CONCLUSIONS: The microbial levels of South African HMDF were within the limits set, with the exception of apricots. SIGNIFICANCE AND IMPACT OF STUDY: The study shows the presence of Salmonella, Staphylococcus and Clostridium in South African HMDF. The presence of thermoduric organisms indicated that the current pasteurization process is not adequate and that the addition of preservatives would be an additional method to ensure safety and quality.     

染料木黄酮对大鼠体内N-羟乙酰神经氨酸含量的影响及其与唾液酸转移酶相互作用的探讨

本研究旨在研究染料木黄酮(Genistein,Gen)对大鼠体内N-羟乙酰神经氨酸(N-glycolylneuraminic acid,Neu5Gc)生物合成的影响。选取80只4周龄SD雄性大鼠,随机平均分为对照组和Gen组,分别灌胃5%的乙醇溶液和300 mg/(kg·d)的Gen溶液。利用荧光高效液相色谱(HPLC-FLD)检测大鼠后腿肌肉、肾脏、肝脏组织中Neu5Gc的含量,并采用Gen与唾液酸转移酶(Sialyltransferase,ST)分子对接,初步探讨了其抑制Neu5Gc合成的机理。结果表明:灌胃15 d时,后腿肌肉和肝脏组织中的Neu5Gc的含量分别降低了13.77%和15.45%,而肾脏组织中Neu5Gc的含量变化差异不显著;30 d时,在肌肉组织中未检出Neu5Gc,在肝脏组织中的Neu5Gc的含量降低了13.35%,肾脏组织中Neu5Gc的含量没有显著的变化;45 d时,在后腿肌肉、肾脏组织和肝脏组织中的Neu5Gc含量分别降低了32.65%、16.80%和32.78%;60d时,在后腿肌肉、肾脏组织和肝脏组织中Neu5Gc含量降低了12.72%、12.30%和11.42%。Gen与ST活性位点残基His319、Ser151、Gly293、Thr328形成氢键,且与残基His302、His301、Trp300、Ser271、Phe292、Thr328、Ser325、Ile274形成疏水作用。因此分子间弱相互作用是导致Gen抑制ST活性的主要原因。该研究结果为后续开展宰前降低红肉中Neu5Gc的方法提供了基础实验方法支撑。     

Comparative content of total polyphenols and dietary fiber in tropical fruits and persimmon

Recent studies have shown that dietary fiber and polyphenols of vegetables and fruits improve lipid metabolism and prevent the oxidation of low density lipoprotein cholesterol (LDL-C), which hinder the development of atherosclerosis. The goal of this study was to measure the total polyphenol and dietary fiber contents of some tropical fruits (i.e., pineapple, wax apple, rambutan, lichi, guava, and mango) and compare the results to the content of these substances in the better characterized persimmon. It was found that lichi, guava, and ripe mango (cv. Keaw) have 3.35, 4.95, and 6.25 mg of total polyphenols in 100 g fresh fruit, respectively. This is significantly higher than in persimmon, pineapple, wax apple, mature green mango, and rambutan [P < 0.0005 for pineapple (Smooth Cayene variant), wax apple, persimmon, rambutan, mature green mango (cv. Keaw); the value of P < 0.001 is found only for pineapple (Phuket, Queen variant)]. The same relationship was observed for the contents of gallic acid and of dietary fiber. It can be supposed that among the studied fruit, lichi, guava, and ripe mango may be preferable for dietary prevention of atherosclerosis.     

Enrichment of sugar content in melon fruits by hydrogen peroxide treatment

Since sweetness is one of the most important qualities of many fruits, and since sugars are translocated from leaves to fruits, the present study investigates photosynthetic activity, activity of sugar metabolizing enzymes, sugar content in leaves and fruits and endogenous levels of hydrogen peroxide in leaves of melon plants treated with various dilutions of hydrogen peroxide, a nonspecific signaling molecule in abiotic stress. For this purpose, 4-month-old melon plants were treated with various concentrations (<50mM) of hydrogen peroxide by applying 300mL per day to the soil of potted plants. The treatments resulted in increased fructose, glucose, sucrose and starch in the leaves and fruits. The most effective concentration of hydrogen peroxide was 20mM. During the day, soluble sugars in leaves were highest at 12:00h and starch at 15:00h. Furthermore, the peroxide treatment increased the photosynthetic activity and the activities of chloroplastic and cytosolic fructose-1,6-bisphosphatase, sucrose phosphate synthase and invertases. Thus, our data show that exogenous hydrogen peroxide, applied to the soil, can increase the soluble sugar content of melon fruits.     

Edible nuts and metabolic health

PURPOSE OF REVIEW: This review summarizes evidence for metabolic health benefits of tree nuts and groundnuts (peanuts). While a role for nuts in the dietary management of LDL-cholesterol is well established, it is evident that regular consumption of nuts may also help to counteract other cardiovascular and metabolic risk factors. RECENT FINDINGS: Nuts are not only energy dense foods, they are rich sources of monounsaturated and polyunsaturated fatty acids and other bioactive nutrients with important metabolic effects. Contrary to expectations, epidemiological studies indicate that regular consumption of nuts is unlikely to contribute to obesity or increased risk of diabetes. In fact, it may help to regulate body weight by suppressing appetite and fat absorption. Nut consumption counteracts dyslipidemia and has the capacity to improve circulatory function through the actions of multiple constituents (arginine, polyphenols) on endothelial mechanisms. SUMMARY: Nuts are densely packaged nutrients with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated in healthy diets. Their potential role in counteracting obesity and the metabolic syndrome warrants further investigation.     

Processing of pistachio nuts

New mechanical procedures for processing pistachio nuts make economical preparation for marketing possible in the United States. These new developments include mechanical dehulling, methods for separating empty nuts from those with well developed kernels, and methods for separating split nuts from those with closed shells.     

Effect of calcium glucarate on beta-glucuronidase activity and glucarate content of certain vegetables and fruits

Glucarate is normally present in tissues and body fluids and is in equilibrium with D-glucaro-1,4-lactone, a natural inhibitor of beta-glucuronidase activity. Dietary calcium glucarate, a sustained-release from of glucarate, elevates the blood level of D-glucaro-1,4-lactone which suppresses blood and tissue beta-glucuronidase activity. A single dose of CaG (4.5 mmole/kg body weight) inhibited beta-glucuronidase activity in serum and liver, lung, and intestinal microsomes by 57, 44, 37, and 39%, respectively. A chronic administration of calcium glucarate (4% in diet) also decreased beta-glucuronidase activity in intestinal and liver microsomes. Maximal inhibition of beta-glucuronidase activity in serum was observed from 12 noon to 2:00 PM. In contrast, maximum inhibition of beta-glucuronidase activity in intestinal and liver microsomes occurred during mornings, although a secondary depression in intestinal microsomes also occurred around 4 PM. A 4% calcium glucarate supplemented diet also inhibited beta-glucuronidase activity by 70% and 54%, of the bacterial flora obtained from proximal (small intestine) and distal (colon) segments of intestine, respectively. Due to the potential effect of dietary glucarate on net glucuronidation and on other metabolic pathways, glucaric acid levels in various foods were determined. The glucaric acid content varied from a low of 1.12-1.73 mg/100 g for broccoli and potatoes to a high of 4.53 mg/100 g for oranges.     

Light signaling genes and their manipulation towards modulation of phytonutrient content in tomato fruits

Due to its economic importance, ease of genetic manipulation, cultivation and processing, the tomato plant has been a target for increasing and diversifying content of fruit phytonutrients by transgenic and non-transgenic approaches. The tomato high pigment (hp) mutations exemplify the latter alternative and due to their positive effect on fruit lycopene content, they were introgressed into elite tomato germplasm for cost effective extraction of this important carotenoid. Interestingly, hp mutant fruits are also characterized by higher fruit levels of other functional metabolites, phenotypes caused by mutations in central genes regulating light signal-transduction. This gene identification suggests that modulation of light signaling machinery in plants may be highly effective towards manipulation of fruit phytonutrients but has never been thoroughly reviewed. This review therefore summarizes the progress which has been made on this valuable approach, emphasizing the consequences of transgenic modulation of light signaling components on the functional properties of the tomato fruit.     

The nuts and bolts of germ-cell migration

In many species, primordial germ cells (PGCs) migrate from the position where they are specified to the site where the gonad develops, where they differentiate into sperm and egg. Germ cells thus serve as an excellent model for studying cell migration in the context of the live organism. In recent years, a number of cues directing the migration of the cells towards their target were identified and some of the relevant molecules and biochemical pathways were revealed. In this review we present those results, focusing on 'cell mechanics' of the process including cell adhesion, traction generation and cell polarization.     

Variation of loganin content in Cornus officinalis fruits at different extraction conditions and maturation stages

Efficient preparation of loganin from Cornus officinalis fruits was investigated. First, effect of extraction conditions on loganin yield was measured. The loganin content in C. officinalis extract was greatly affected by ethanol concentration and extraction time whereas extraction temperature exerted relatively little effect. Response surface methodology with Box–Behnken design suggested optimized extraction condition for maximum loganin yield as ethanol concentration, 32.0%; temperature 46.2 °C and extraction time, 46.7 min, which yielded 10.4 μg loganin/mg dried fruit. Next, the effect of maturation stage of C. officinalis fruits on loganin content was investigated. The loganin content in the extract of C. officinalis fruits was decreased as the maturation process. The loganin content in the unripe fruits was 18.0 μg/mg extract whereas reduced to 13.3 μg/mg extract for ripe fruits. Taken together, our present study suggested the importance of extraction condition and maturation stages for efficient preparation of loganin from C. officinalis fruits.     

‘恭城月柿'不同生育期果实和叶片单宁组分含量的变化

柿单宁是一种重要的食品功能成分,广泛应用于食品、医疗等领域,研究柿单宁的生物生产特性对其产业应用具有重要意义。该研究以广西特色涩柿品种‘恭城月柿’为材料,测定了幼果期、膨大期、成熟前期、成熟期和成熟后期柿果肉、果皮和叶片的可溶性单宁含量,并利用液质联用色谱对全部样品中6种单宁组分[没食子酸(GA)、没食子儿茶素(GC)、儿茶素(CA)、芦丁(Rutin)、表没食子儿茶素(EGC)和表儿茶素(EC)]进行了定量分析。结果表明:柿果肉和果皮中含有丰富的可溶性单宁,在膨大期含量最高,分别达到21.93 mg·g~(-1)和18.41 mg·g~(-1),随着果实进入成熟阶段显著下降;柿叶片的可溶性单宁含量较低,并且在整个生育期内无明显变化。另外,在柿果肉中检测到GA、GC和CA 3种单宁组分,其中GA含量显著高于其他组分;在柿果皮中检测到GA、GC、CA、Rutin和EGC 5种组分,其中CA含量最高,EGC仅在幼果期和膨大期有痕量检出;在柿叶中检测到全部6种单宁组分,其中整个生育期CA含量极高,EGC和EC均为痕量检出。由此可知,幼果期至膨大期的柿果实可产出较多可溶性单宁,其中果肉中含有较多的GA组分,果皮中含有大量的CA组分,柿叶片在整个生育期均可产出极为丰富的CA单宁组分。该研究为柿单宁的功能性开发利用提供基础数据。     

Determination of plasma genistein fatty acid esters following administration of genistein or genistein 4'7-O-dioleate in monkeys

Soy-derived isoflavone phytoestrogens, such as genistein (4',5,7-trihydroxyisoflavone), have been shown to protect low-density lipoprotein from oxidation. In addition, human plasma was previously shown to be capable of converting genistein into lipophilic fatty acid esters that accumulate in lipoproteins in vitro. We developed a method for the quantitation of genistein fatty acid esters in plasma. Furthermore, the method was utilized to measure genistein ester concentrations in monkey plasma following administration of genistein or genistein 4',7-O-dioleate. After extraction from plasma, genistein fatty acid esters were separated from unesterified genistein by Sephadex LH-20 column chromatography. The genistein ester fraction was hydrolyzed by saponification and purified by a second chromatography on Sephadex LH-20. The hydrolyzed genistein esters were measured by time-resolved fluoroimmunoassay. Adult female rhesus monkeys (n=10) received a subcutaneous injection of genistein (24 mg, n=2) or genistein 4',7-O-dioleate (71 mg, n=3) or an oral dose of genistein (24 mg, n=2) or genistein 4',7-O-dioleate (71 mg, n=3). Plasma was collected at 4, 8, and 24 h post-dosing. Following subcutaneous administration of genistein 4',7-O-dioleate, the plasma concentrations of genistein esters became elevated in two out of three monkeys with 8-h values exceeding 7.5 nmol/L and 24-h values above 12 nmol/L. Other treatments resulted in lower plasma values ranging between 2.7 and 6.1 nmol/L. The lower limit of detection for the method was 1.44 nmol/L. Subcutaneously administered genistein 4',7-O-dioleate was also converted to water-soluble conjugates, but oral administration did not elevate plasma genistein fatty acid ester levels. The results suggest that it may be possible to introduce intact genistein ester molecules into plasma by parenteral but not oral administration.     

The content of photosynthetic pigments and the light conditions in the fruits and leaves of sweet pepper

Investigations were carried out on the fruits of sweet pepper at its two development stages: on green fruits, on mature red and yellow fruits and on leaves. The content of the photosynthetic pigments and the optical properties were examined. In the green fruits when compared with leaves the content of the photosynthetic pigments is smaller by 40 to 50 % and the value of the ratio: chlorophyll a/b is lower. Chlorophyll is absent in mature fruits, while the content of carotenoids is a few times higher. The optical properties of green fruits and of the leaves in the PAR (photosynthetically active radiation) range are the same. In the range 700–1100 nm the green fruits show smaller reflectance and transmittance and a few times greater absorptance of irradiation which contributes to the warming up of the seed bag, while small absorptance of leaves in this range protects them against overheating. In mature fruits, in the PAR range, the reflectance and transmittance are higher, while the absorptance of irradiation in comparison with that of green fruits is smaller. In the range 700 – 1100 nm the changes are rather small and refer to the increase of reflectance and reduction of absorptance, while the transmittance of irradiation remains unchanged.     

Sclerotinia fructigena infection and chlorogenic acid content in relation to antifungal compounds in apple fruits

Several organic acids, known to occur in many apple varieties, were shown to be present in the juice of the variety Edward VII. When these were supplied separately to the brown rot pathogen, Sclerotinia fructigena, growing in culture, chlorogenic acid and quinic acid were both readily converted to compounds of higher antifungal activity, one of which was 4-hydroxybenzoic acid. The chlorogenic acid content of concentrated healthy fruit juice was ?6 mg/g, whereas the corresponding syrup from diseased fruit contained only ?2 mg/g. The possible significance of this metabolism of chlorogenic acid by the fungus is discussed.