Optimization of cold plasma processing conditions for fresh-cut kiwifruit slices by using response surface methodology.

The work aims to optimize the process of cold plasma for fresh-cut kiwifruit. The effects of discharge times, treatment voltages, and slice thickness as well as the interaction between them were investigated. Factor analysis was used to screen out the characteristic indices of fresh-cut kiwifruit. Design-Expert software was used to design three-factor response surface tests and find the optimal parameters. The results revealed that the quality indices of fresh-cut kiwifruit were the color difference, brittleness, and solid-acid ratio, the established binomial regression equations were significant (P < 0.05). At the optimal level: 26 kV treatment voltage, 120 s discharge times, and 10 mm slice thickness, the optimized test values for the color difference, brittleness, solid-acid ratio and decreased logarithm value of total plate count were 2.25, 128.96 g·s, 18.03 and 2.30 lg(CFU·g-1), respectively. Cold plasma could significantly improve the inactivation of bacteria in fresh-cut kiwifruit.

Effects of cold plasma treatment on cherry quality during storage.

Cherry samples were treated with cold plasma under different voltages (40, 60, 80 kV) and different treatment durations (60, 80, 100, 140 s), then stored in a refrigerator at 0 ℃. Data on the decay rate, respiration rate, and physiological properties of the cherries and their correlational relationships after different treatments of cold plasma were collected under the conditions of ambient temperature and dry air. The decay rate, respiration rate, total soluble solids, total phenol, flavonoids, anthocyanin, VC, titratable acidity, firmness, and a* value were investigated at regular intervals to analyze the quality of the cherries under different treatment conditions. Additionally, the total colony number was estimated at the end of storage. The results indicated that cold plasma treatment under moderate conditions was effective for prolonging cherry storage, inactivating microorganisms, decreasing the decay rate, and inhibiting respiration with either no compromise on the cherry quality or only a slightly noticeable influence. A significant positive correlation was found between the decay rate and respiration rate, as well as between the VC content and titratable acidity. Antioxidant contents and firmness were found to be negatively correlated with the a* value. In conclusion, this study demonstrated that cold plasma has potential applications in the storage and preservation of cherries.

Nutritional properties and biological activities of kiwifruit (Actinidia) and kiwifruit products under simulated gastrointestinal in vitro digestion.

BACKGROUND: Kiwifruit is one of the most commercialized fruits on the international market, which has notable high nutritional and medicinal value with many health benefits. In addition to being consumed fresh, numerous kiwifruit products are popular, such as kiwifruit juice, vinegar, dried slices, jam, wine, yogurt, and jelly. Although many studies have described the nutritional properties of kiwifruit, investigations on the nutritional properties of kiwifruit products remain limited, especially for kiwifruit products made from raw kiwifruit. METHODS: Nutritional properties and biological activities of kiwifruit and kiwifruit products, as well as the digestive and absorption characteristics of their nutritional substances, were investigated. RESULTS: Kiwifruit, juice, wine, and vinegar were observed to be rich in vitamin C (VC) and polyphenol and exhibited high biological activities, whereas dried kiwifruit slices and jam showed higher amounts of mineral elements. During oral digestion, VC and polyphenol showed similar absorption characteristics, while mineral elements exhibited a number of different trends. A good release rate of all nutritional substances was observed during stomach digestion, while the release rate decreased in serum-available, colon-available, and post-colonic fractions. Eating dried slices and jam supplied high amounts of mineral elements, while eating kiwifruit supplied the most comprehensive nutritional substances. The biological activities detected in raw foodstuffs were much higher than those detected after in vitro digestion. Furthermore, kiwifruit and wine showed the highest biological activities, while dried kiwifruit slices showed the lowest biological activities. CONCLUSION: These results increased our understanding of the nutritional properties of kiwifruit and its products, providing new information and scientific recommendations to consumers for kiwifruit consumption and to producers for kiwifruit production.

Nutrient compositions and antioxidant capacity of kiwifruit (Actinidia) and their relationship with flesh color and commercial value.

The nutritional quality and antioxidant capacity of China domestic kiwifruit and imported kiwifruit with different prices and the relationships of retail price among cultivars, nutritional qualities and flesh color were investigated. Results showed that cultivar was the main factor influencing nutritional quality, though the product region could also affect the cultivar characteristics to some extent. Additionally, nutritional quality and antioxidant capacity of kiwifruit had no relationship to the product region. What's more, there was no correlation among the nutrient compositions, antioxidant capacity and retail price of kiwifruit. At the same time, the flesh color was associated with greater commercial value but was not higher nutritional quality or antioxidant capacity. Thus indicates to consumers that imported kiwifruit were not all superior to local versions, and the priciest kiwifruit did not equal to the most nutritious kiwifruit, also the color kiwifruit. There still need more research to help consumers to choose kiwifruit.

Cloning and characterization of Bombyx mori PP-BP a gene induced by viral infection.

The ENF peptide family, so termed after the consensus sequence in their amino termini (Glu-Asn-Phe-), is assumed to play multiple important roles in defense reactions, growth regulation, and homeostasis of Lepidopteran insects. The paralytic peptide of Bombyx mori (BmPP) is one such peptide that is involved in the paralytic and plasmatocyte-spreading activities in the hemocyte immune reaction. The growth-blocking peptide of Pseudaletia separata (PsGBP), which is also a member of the ENF peptide family, has similar functions that can reportedly be attenuated by the growth-blocking peptide-binding protein (GBP-BP). Using the fluorescent differential display (FDD) technique, the differential expression pattern of genes in highly susceptible silkworm strain 306 were analyzed, following infection with B. mori nuclear polyhedrosis virus (BmNPV), and a differential band (G12(782)) was obtained from the hemolymph RNA pools. Using 5'-RACE with a specially designed primer based on the FDD study, a 1,401 bp cDNA clone was obtained containing a 1,311 bp open reading frame (ORF, GenBank accession number DQ306881). The deduced protein was highly homologous in primary structure to GBP-BP and was termed B. mori paralytic peptide-binding protein (PP-BP). The B. mori PP-BP gene is organized into two exons and only one intron, using bioinformatics searches.Using RT-PCR analysis, it was found that the B. mori PP-BP gene was expressed almost exclusively in the hemolymph. Real-time quantitative PCR analysis indicated that the B. mori PP-BP mRNA level in B. mori strain 306 exposed to BmNPV was much higher than that in B. mori strain without the virus infection. This result implies that the B. mori PP-BP is related to the cellular immune response after BmNPV invades the hemolymph.

[Complete nucleotide sequence analysis of Bombyx mori Densonucleosis virus type 3 VD2 (China isolate)].

The genome of Bombyx mori densonucleosis virus type 3 (China isolate) contains two kinds different single-stranded linear DNA molecules (VD1, VD2). The VD2 was purified and cloned into the pUC119 vector, and the complete nucleotide sequence of VD2 was determined. Sequence analysis showed that the VD2 genome sequence consisted of 6022 nts, including inverted terminal repeats (ITRs) of 524 nts. In the viral genome, two major open reading frames (ORF1 and ORF2) in the plus strand and one minor ORF (ORF3) in the complementary strand were identified. Computer analysis suggested the plus stand ORF1 and the minus strand ORF3 most likely encode the major nonstructural protein, while the plus stand ORF2 most likely encodes the major structural protein. Comparing the complete genome sequence of BmDNV-3 VD2 with that of BmDNV-2 VD2 (Yamanashi isolate) demonstrated that they shared 97.7% genome sequence in the VD2 region, with substitutions of 132 nucleotides, deletions of 11 nucleotides and insertions of 2 nucleotides in the VD2 region of BmDNV-3. The results suggested that BmDNV-3 is closely related to BmDNV-2, but with some differences, giving a better understanding about the variation of the viruses and providing clues to their evolution.

Phylogenetic analysis of Nosema antheraeae (Microsporidia) isolated from Chinese oak silkworm, Antheraea pernyi.

The microsporidian Nosema antheraeae is a pathogen that infects the Chinese oak silkworm, Antheraea pernyi. We sequenced the complete small subunit (SSU) rRNA gene and the internal transcribed spacer (ITS) of N. antheraeae, and compared the SSU rRNA sequences in other microsporidia. The results indicated that Nosema species, including N. antheraeae, formed two distinct clades, consistent with previous observations. Furthermore, N. antheraeae is clustered with N. bombycis with high bootstrap support. The organization of the rRNA gene of N. antheraeae is LSU-ITS1-SSU-ITS2-5S, also following a pattern similar to the Nosema type species, N. bombycis. Thus, N. antheraeae is a Nosema species and has a close relationship to N. bombycis.